Scholarly article on chlorocycloocta-1,5-diene(diisopropyl-2-pyridiniumylphosphane)rhodium(I) 4-methylphenylsulfonate 1195987-35-9 from Organometallics p. 6383

Organometallics 2009, 28, 6383–6401 6383

DOI: 10.1021/om900324a

Investigation of the Dynamic Solution Behavior of

Chloro(diene)rhodium(I) Phosphine Complexes with a Pendant

Unsaturated Heterocycle at Phosphorus (2-pyridyl, 2-imidazyl;

diene = COD, NBD)

Andreas Bruck^†,‡and Klaus Ruhland*^,†,‡

€

†

€

Lehrstuhl fu€r Chemische Physik und Materialwissenschaften, Institut fu€r Physik, Universitat Augsburg,

Universitatsstrasse 1, D-86159 Augsburg, Germany, and Lehrstuhl fur Anorganische Chemie, Department

‡

€

Chemie, Technische Universitat Munchen, Lichtenbergstrasse 4, D-85747 Garching bei Munchen, Germany

€

Received April 27, 2009

Reaction of chloro(diene)rhodium(I) dimer with 2-pyridyl- and 2-imidazylphosphines resulted in

the formation of the four-coordinate, square-planar complexes chloro(diene)rhodium-κ¹-P-phos-

phine [diene = 1,5-cyclooctadiene (COD), bicyclo[2.2.1]hepta-2,5-diene (NBD)]. The nitrogen in the

β-position to phosphorus provoked a fast exchange of the olefin sites in solution. Influences on this

system were investigated through variation of the substituents on the phosphorus, the diene, the

metal, and the heterocycle and the substitution pattern of the heterocycle. Additional isotopic

labeling experiments were performed with a deuterium (1-d₁) or a trideuteromethyl group (1-Me-d₃)

in the ortho-position to nitrogen in 1 and one deuterium in each of the olefinic positions of COD

(1-COD-d₂). These findings resulted in an inverse kinetic isotope effect (KIE) in the case of 1-Me-d₃

and 1-COD-d₂. No KIE was found by complete line-shape analysis when the pyridyl-nitrogen was

labeled with ¹⁵N. The temperature dependence of T₁relaxation times for the para-proton in the

pyridyl moiety was found to be a diagnostic criterion for an interaction of the pyridyl moiety with the

rest of the complex, allowing the estimate of the strength of the attractive part of this interaction. No

ground-state experimental proof (X-ray structure, scalar coupling constants in NMR spectroscopy)

was found for this kind of interaction. DFT calculations support the nonexistence of ground-state

complexes with Rh-coordinated pyridyl-nitrogen. Calculations on the pathway of the dynamic

behavior in comparison to the experimental results exclude an interaction of the pyridyl-nitrogen

with the COD double bonds and speak in favor of a temporary coordination of the pyridyl nitrogen

to the metal center in a transition state. The calculated and measured kinetic data (including the

KIEs) are in good agreement with this mechanism.

Introduction

(site exchange of the coordinated double bonds) has been

observed on the spectral NMR time scale in this type of

complex.²Proposals of why this occurs have included an

intramolecular rotation of the chelating diolefin in a tetra-

coordinated complex via a pseudotetrahedral intermediate, a

dissociative exchange of spectator ligands via a T-shaped

three-coordinated intermediate, or an associative pseudo-

rotation within a pentacoordinated intermediate. Despite

numerous reports, the mechanism of this fluxional behavior

is still under dispute.

In this contribution we report new insight into the mecha-

nism using multinuclear VT-NMR spectroscopy, X-ray

analysis, and DFT calculations concerning the fluxional

behavior of group 9 complexes [diolefin]M^I(PR₂Py)(X),

shown in Scheme 1 as type B.

Chelating diolefin complexes of Rh(I) and Ir(I) are well-

known precursors for the synthetic coordination chemis-

try and the application of these metals as catalysts.¹In

several cases a fluxional behavior of the chelating diolefin

*Corresponding author. E-mail: klaus.ruhland@ch.tum.de.

(1) (a) Jalon, F. A.; Manzano, B. R.; Caballero, A.; Carrion, M. C.;

Santos, L.; Espino, G.; Moreno, M. J. Am. Chem. Soc. 2005, 127, 15364.

(b) Drent, E.; Arnoldy, P.; Budzelaar, P. H. J. Organomet. Chem. 1993, 455,

247. (c) Drent, E.; Arnoldy, P.; Budzelaar, P. H. J. Organomet. Chem. 1994,

475, 57. (d) Grotjahn, D. B.; Lev, D. A. J. Am. Chem. Soc. 2004, 126, 12232.

(e) Grotjah, D. B.; Kragulj, E. J.; Zeinalipour-Yazdi, C. D.; Miranda-Soto, V.;

Lev, D. A.; Cooksy, A. L. J. Am. Chem. Soc. 2008, 130, 10860. (f) Labonne,

A; Kribber, T.; Hintermann, L. Org. Lett. 2006, 8, 5853. (g) Kribber, T.;

Labonne, A.; Hintermann, L. Synthesis 2007, 2809.

(2) (a) Cesar, V.; Bellemin-Laponnaz, S.; Gade, L. H. Eur. J. Inorg.

Chem. 2004, 3436. (b) Cesar, V.; Bellemin-Laponnaz, S.; Wadepohl, H.;

Gade, L. H. Chem.;Eur. J. 2005, 11, 2862. (c) Weller, A. S.; Mahon, M. F.;

Steed, J. W. J. Organomet. Chem. 2000, 614-615, 113. (d) Miranda-Soto,

V.; Prez-Torrente, J. J.; Oro, L. A.; Lahoz, F. J.; Martin, M. L.; Parra-Hake,

M.; Grotjahn, D. B. Organometallics 2005, 25, 4374. (e) Haarman, H. F.;

Bregman, F. R.; Ernsting, J.-M.; Veldman, N.; Spek, A. L.; Vrieze, K.

Organometallics 1997, 16, 54.

Thus, the focus of our studies is set on the influence of a

nitrogen atom in ortho-position of the aryl group connected

to the P donor (1P,3N relation)^3a-con the fluxional behavior

of the chelating diolefin ligand. The behavior of the nitrogen-

free analogues (type A in Scheme 1) is discussed in a separate

paper.¹³

r

2009 American Chemical Society

Published on Web 10/26/2009

pubs.acs.org/Organometallics

6384 Organometallics, Vol. 28, No. 22, 2009

Bru€ck and Ruhland

Scheme 1

in the ³¹P{¹H} NMR spectrum by a shift of the doublet from

44.6 ppm (¹J_PRh= 148.5 Hz) for the chloro compound to

46.1 ppm (¹J_PRh= 145.5 Hz) for the bromo compound. Both

compounds are identical in the ¹H NMR spectra. The second

compound can be assigned to be the bromo compound by

X-ray analysis of 1-pCF₃and Br-1-pCF₃mixed single crystals

(ratio Cl/Br = 2:1, redissolving of the crystals resulted in the

same ³¹P{¹H} and ¹H NMR spectra). As the halide did not

show a high impact on the dynamic behavior of the studied

system, no further effort was undertaken to purify 1-pCF₃

and Br-1-pCF₃.

Since ¹⁵N NMR spectroscopy was presumed to provide

insight into the solution behavior of the pyridyl moiety in

general, and eventually to interactions between nitrogen and

other groups of the complex by direct coupling, we syn-

thesized the ¹⁵N-labeled ligand diisopropyl(4,6-dimethyl-2-

pyridyl)phosphine, ¹⁵N-Me₂-L1, and the ¹⁴N counterpart

Me₂-L1 for direct comparison of the solution behavior of the

final complexes (Scheme 4).^4,5A palladium-catalyzed cou-

pling of aryl and binaphthyl triflates with diphenylphosphine

oxide and subsequent reduction of the phosphine oxide with

trichlorosilane was applied. In addition to ¹H, ³¹P{¹H},

¹³C{¹H}, and ¹⁵N{¹H} NMR spectroscopy, elemental ana-

lysis, and mass spectroscopy, crystals suitable for X-ray

diffraction were obtained from a saturated acetone solution,

confirming the structure of complex 1-Me₂.

Scheme 2. Synthesis of the Ligands

The abstraction of chloride in 1 with silver tetrafluoro-

borate resulted in complex 1-BF₄, which is static on the spec-

1

tral time scale of H NMR spectroscopy (Scheme 5). The

Scheme 3. Complexes Used in This Study

nitrogen coordinates to the rhodium, resulting in a four-

membered ring. In addition to the absence of line broadening

1

for the COD signals in the H NMR spectrum, the ring

formation is accompanied by a typical upfield shift in the ³¹P

NMR from 43.3 ppm to -11.9 ppm and a reduction of the

coupling constant J_PRhfrom 144.7 Hz to 120.9 Hz. 1-BF₄

1

and its derivatives were stable only in solution and decom-

posed during isolation and crystallization attempts, showing

the weak coordination in this unfavorable four-membered

ring system.

Addition of 1 equiv of para-toluenesulfonic acid (p-TsOH)

to a NMR sample of 1 in CDCl₃resulted in deceleration of

the olefin exchange rate (vide infra) and, thus, a sharpening of

the olefin signals, and a slight broadening of the pyridyl

signals in combination with a low-field shift of the ortho-

proton from 8.67 ppm to 9.40 ppm. The protonation of the

nitrogen also resulted in a low-field shift in the ³¹P NMR

Results and Discussion

Synthesis of the Ligands and Complexes. The pyridine-

containing ligands used in our study were synthesized start-

ing from the corresponding 2-bromopyridine derivatives by

lithiation with n-butyllithium (ⁿBuLi) followed by a reac-

tion with chlorodiisopropylphosphine (ⁱPr₂PCl) or chlorodi-

phenylphosphine (Ph₂PCl) (Scheme 2).^3d-gThe imidazole-

containing ligands were synthesized in a similar manner by

deprotonation of the N-alkylated imidazoles at the C2

position with n-butyllithium and further reaction with chlor-

odiisopropylphosphine.

1

from 43.3 ppm to 48.7 ppm and an increase in the J_RhP

coupling constant from 144.7 Hz to 151.5 Hz. The same

result is obtained when first quantitively protonating the

ligand and then applying it to [(COD)RhCl]₂.

We find evidence for a hydrogen bond in 1-H^þ, as shown

in Scheme 5, by the following facts: (i) The change in ³¹P

chemical shift to higher ppm is in accordance with the

The rhodium and iridium complexes (Scheme 3) were

obtained in very good yields by stirring 1 equiv of

[(diolefin)MCl]₂with 2 equiv of the ligand in dichloro-

methane.

In the case of 1-pCF₃, the use of the crude ligand (L1-pCF₃)

was not sufficient due to the formation of 20-30% of the

bromo derivative (Br-1-pCF₃) of the complex. This can be

explained by elimination of lithium bromide in the ligand

synthesis and further extraction by coordination to L1-pCF₃.

The 1-pCF₃and Br-1-pCF₃complexes can be distinguished

(3) (a) Newkome, G. R. Chem. Rev. 1993, 93, 2067. (b) Grotjahn, D. B.

Dalton Trans. 2008, 6497. (c) Zhang, Z. Z.; Cheng, H. Coord. Chem. Rev.

1996, 147, 1. (d) Spencer, L. P.; Altwer, R.; Wie, P.; Gelmini, L.; Gauld, J.;

Stephan, D. W. Organometallics 2003, 3841. (e) Jansen, A.; Pitter, S. J. Mol.

Catal. A 2004, 217, 41. (f) Gros, P.; Younes-Millot, C. B.; Fort, Y.

Tetrahedron Lett. 2000, 41, 303. (g) Scrivanti, A.; Beghetto, V.; Matteoli,

U. Adv. Synth. Catal. 2002, 344, 543.

€

(4) (a) Anschutz, R.; Bendix, P.; Kerp, W. Anal. Chem. 1890, 256, 148.

(b) Ritter, K. Synthesis 1993, 735. (c) Schwan, A. L. Chem. Soc. Rev. 2004,

33, 218.

(5) Beletskaya, I. P.; Kazankova, M. A. Russ. J. Org. Chem. 2002, 38,

1391.

Article

Organometallics, Vol. 28, No. 22, 2009 6385

Scheme 4. Synthetic Route to the ¹⁵N-Labeled Ligand ¹⁵N-Me₂-L1 and Further Reaction to the Rhodium Complex 1-Me₂-¹⁵N

(and Their Unlabeled Counterparts Me₂-L1 and 1-Me₂)

Scheme 5

formation of a six-membered ring; (ii) a broad peak at

1

showed the same overall behavior, with a general shift

to higher temperatures (T_c= 318 K) so that even at 373 K

no sharp signals were detected. The decrease in line-width

broadening of the olefinic signals was also observable in the

¹³C{¹H} NMR spectra (Figure 2), so that below 253 K two

broad singlets at about 70 and 103 ppm in CDCl₃were

obtained. Upon further cooling to 213 K, the broad signals

developed into a doublet at 69.5 ppm (¹J_CRh= 13.2 Hz) for

16.2 ppm in H NMR spectroscopy resolved at -60 °C;

(iii) samples of 1-H^þwere not stable in solution and decom-

posed completely within a few hours. ³¹P NMR reaction

control showed that one of the intermediate decomposition

products is the corresponding cationic rhodium complex to

1-BF₄, indicating the release of HCl within the course of

decomposition. Similar hydrogen bonding behavior has

previously been reported.⁶

the olefinic group cis to phosphorus and a weakly resolved

doublet of doublets at 102.8 (¹J_CRh= 11.0 Hz, J_CP

2

VT 1D NMR Studies. The starting point in this study was

the complex chlorocycloocta-1,5-diene(diisopropyl-2-pyri-

dylphosphine)rhodium (1). At room temperature (298 K),

=

7.3 Hz) for the olefinic group trans to phosphorus. The allylic

groups showed one very broad signal at about 32 ppm at

room temperature, which sharpened into a broad singlet at

328 K and split into two singlets at 28.4 and 32.7 ppm below

253 K.

The whole process is reversible, and the VT NMR mea-

surements could be repeated several times without change in

the dynamic behavior of the COD signals and without

decomposition of the sample. At this point we must expli-

citely state that the doublet in the ³¹P{¹H} NMR spectrum

did not undergo any change in shape or coupling constant

upon cooling or warming.

This fluctuation of the COD is a more general pheno-

menon for substituted pyridines.⁷We investigated the influ-

ences on the system by changing the substituents on the

pyridine ring, the heterocycle itself, the additional substitu-

ents on the phosphorus ligand, the metal, and the diolefin.

In addition to T_c, complete line-shape analysis for the

determination of the activation parameters (ΔH^q, ΔS^q, E_a)

1

all signals in the H NMR spectrum (400.13 MHz) were

sharp and at the expected chemical shifts except for the

olefinic protons, which vanished in the baseline. Addition-

ally, the allylic signals in the ¹³C{¹H} NMR (100.6 MHz)

spectrum showed up as one very broad signal at about 31

ppm. At the same time, the ³¹P{¹H} NMR spectrum (161.1

MHz) showed a sharp doublet at 43.3 (d, ¹J_PRh= 144.7 Hz)

ppm.

¹H VT NMR measurements in CDCl₃through the tem-

perature range from 213 to 323 K (Figure 1) in 10 deg steps

were performed. The olefinic protons showed two sharp

signals at 3.33 and 5.23 ppm at 213 K, which broadened

1

upon warming to 273 K (the two H signals within each

double bond are equivalent). Between 283 and 303 K, these

signals could be observed only by enlargement of the spec-

trum, so that a coalescense temperature T_cof 298 K could be

determined (T_cconcerns the coalescence temperature of the

olefinic proton resonances in the COD ligand throughout

the whole paper). At higher temperatures, a very broad

singlet around 4.28 ppm was obtained. A ¹H VT NMR series

in toluene-d₈in the temperature range from 183 to 373 K

(7) (a) Tejel, C.; Ciriano, M. A.; Bravi, R.; Oro, L. A.; Graiff, C.;

Galassi, R.; Burini, A. Inorg. Chim. Acta 2003, 347, 129. (b) Grassi, M.;

De Munno, G.; Nicolo, F.; Lo Schiavo, S. J. Chem. Soc., Dalton Trans.

1992, 2367. (c) Arena, C. G.; Rotondo, E.; Faraone, F. Organometallics

1991, 10, 3877. (d) Chan, A. S. C.; Chen, C.-C.; Cao, R. Organometallics

1997, 16, 3469. (e) Kurtev, K.; Ribola, D.; Jones, R. A.; Cole-Hamilton, D. J.;

Wilkinson, G. J. Chem. Soc., Dalton Trans. 1980, 55. (f) Arena, G. C.;

Faraone, F.; Lanfranchi, M.; Rotondo, E.; Tiripicchio, A. Inorg. Chem. 1992,

31, 4797. (g) Casares, J. A.; Espinet, P.; Martin-Alvarez, J. M.; Santos, V.

Inorg. Chem. 2006, 45, 6628.

(6) (a) Camus, J. M.; Andrieu, J.; Poli, R.; Richard, P.; Baldoli, C.;

Maiorana, S. Inorg. Chem. 2003, 42, 2384. (b) Selent, D.; Baumann, W.;

€

Kempe, R.; Spannenberg, A.; Rottger, D.; Wiese, K.-D.; Borner, A Orga-

nometallics 2003, 22, 4265. (c) Andrieu, J.; Camus, J.-M.; Richard, P.; Poli,

R.; Gonsalvi, L.; Vizza, F.; Peruzzini, M. Eur. J. Inorg. Chem. 2006, 51.

6386 Organometallics, Vol. 28, No. 22, 2009

Bru€ck and Ruhland

Figure 1. ¹H VT NMR spectra of 1 in the temperature range from 213 to 323 K.

Figure 2. ¹³C{¹H} VT NMR spectra of 1 at 213, 253, 293, and 328 K in CDCl₃. Only the dynamic COD section is shown in the range

from 25 to 105 ppm.

was performed. Another descriptive value is T₀, which

represents the lowest temperature in the 10 K step VT series

without broadening of the signal. The VT NMR measure-

ments of one sample were performed three times at three

different concentrations (typically 20 mg of complex in 0.5,

1.0, and 1.5 mL of CDCl₃). The variations of the three

activation parameters for each sample were usually small

(1-2 kJ/mol for ΔH^q), so that the dynamic process is

independent of the concentration, and a first-order kinetic

approach is proposed. An exemplary Eyring plot for

the determination of the activation parameters of 1 is

depicted in Figure 3. Complex 1 served as a benchmark for

Figure 3. Eyring plot of the dynamic behavior in 1.

Article

Organometallics, Vol. 28, No. 22, 2009 6387

Table 1. Activation Parameters for the Pyridine Derivatives

solvent

ΔH^q[kJ/mol]

ΔS^q[J/(mol K)]

E_a[kJ/mol]

T₀[K]^a

T_c[K]^b

1

CDCl₃

Tol-d⁸

C₆D₆

44.6 ( 0.7

49.4 ( 0.8

51.9 ( 1.2

45.8 ( 0.5

39.9 ( 0.6

45.1 ( 0.8

42.4 ( 0.9

37.6 ( 0.3

35.4 ( 0.6

35.6 ( 0.7

44.1 ( 0.7

42.9 ( 0.7

40.8 ( 0.6

42.2 ( 0.8

36.0 ( 0.8

28.3 ( 0.7

-31 ( 195

-29 ( 195

-21 ( 194

-25 ( 196

-47 ( 196

-31 ( 194

-46 ( 194

-59 ( 196

-63 ( 195

-41 ( 195

-44 ( 195

-20 ( 194

-46 ( 195

-54 ( 195

45.9 ( 0.7

52.0 ( 0.8

53.9 ( 1.3

46.6 ( 0.5

41.1 ( 0.6

45.9 ( 1.0

43.3 ( 0.8

38.7 ( 0.4

36.8 ( 0.6

36.8 ( 0.8

45.0 ( 0.7

43.9 ( 0.7

41.9 ( 0.6

43.4 ( 0.8

37.3 ( 0.8

29.8 ( 0.6

233

253

298

318

290

293

298

306

299

288

303

288

248

258

233

1

1-d₁

1-COD-d₂

I-1

CDCl₃

CD₂Cl₂

233

223

233

223

243

223

e213

213

<173

1-Me

1-Me-d₃

1-Me₂

1-Me₂-¹⁵

N

1-pCF₃

Br-1-pCF₃

Ir-1

nbd-1

2

nbd-2

^aT₀: first temperature without line-broadening. ^bT_c: coalescence temperature.

the comparison with other derivatives (enthalpy of activa-

tion ΔH^qof 44.6 ( 0.67 kJ/mol and T_cof 298 K).

Influence of the Solvent. The change of solvent from CDCl₃

to toluene-d₈or benzene-d₆resulted in an increase of T_cby

about 20 K to 318 K and ΔH^‡to 49.4 ( 0.83 and 51.9 (

1.2 kJ/mol, respectively (for a comparison of all activation

parameters see Table 1).

accuracy of the measurements. To further investigate the

influence of the halide, complex 1 was transformed into its

iodo derivative (I-1) through a similar procedure using

AgBF₄and NaI. The determined activation parameters

and temperatures for 1 and I-1 were again identical, support-

ing the assumption that the halide plays a minor role in

influencing the dynamic behavior. Additionally, NMR ex-

periments were performed with n-tetrabutylammonium

chloride as additive, which should shift a possible dissocia-

tive equilibrium to the side of the neutral species and

eventually stop or slow the exchange rate if a dissociation

of the halide is involved. The obtained activation parameters

and temperatures were very similar to the results without

excess halide.

Influence of the Additional Substituents on the Phosphorus.

Substitution of the isopropyl groups (1) on the phosphorus

by phenyl groups (2) had an accelerating effect on the

dynamic process (Table 1), so that T₀reduced to 213 K

and T_cto 258 K. This was accompanied by a decrease of the

activation parameters, e.g., ΔH^qdropped to 36.0 ( 0.79

kJ/mol (ΔΔH^q= 8.6 kJ/mol).

Influence of the Diene. A similar shift of T₀and T_cwas

caused by substitution of cycloocta-1,5-diene (1) for norbor-

na-2,5-diene (nbd-1), even though the activation enthalpy

remained similar (ΔΔH^q= 2.4 kJ/mol). The accelerating

effect of the phenyl fingers on phosphorus (2) and the

norborna-2,5-diene (nbd-1) is additive: The room-tempera-

ture ¹H NMR spectrum of nbd-2 exhibited for the first time

one sharp singlet for both olefinic groups at 4.24 ppm. The

VT NMR measurements in CD₂Cl₂did not lead to separated

sharp signals for both olefinic groups (T₀< 173 K), and a

coalescense temperature T_cof 233 K was obtained. This

cooperative effect also resulted in the lowest enthalpy of

activation (ΔH^q= 28.3 ( 0.68 kJ/mol; ΔΔH^q= 16.3 kJ/mol

compared to 1) of this study.

Influence of the Metal Center. The change of the rhodium

metal center of 1 to iridium (Ir-1) resulted in a shift of the

dynamic values T₀and T_cof 10 K to lower temperatures and

a reduction of the enthalpy of activation ΔH^qof ca. 4 kJ/mol.

Influence of Isotopic Labeling. Scheme 6 contains the

labeled compounds that have additionally been examined

(see Tables 1 and 2). The deuterium substitution of the

methyl group in 1-Me resulted in a decrease of T₀to

223 K, T_cto 299 K, and ΔH^qto 37.6 ( 0.34 kJ/mol (ΔΔH^q=

4.8 kJ/mol to 1-Me). In comparison, the introduction

of deuterium in ortho-position (1-d₁; deuteration grade

Influence of ortho-Substituents to the Pyridyl-Nitrogen.

The change from a proton to a methyl group (1-Me) had a

very small effect on the activation enthalpy (ΔH^q= 42.4 (

0.91 kJ/mol), but T_c(306 K) slightly increased. However, the

substitution of the proton by a more sterically demanding,

electron-withdrawing trifluoromethyl (1-oCF₃) or a tri-

methylsilyl group (1-TMS; minimum group van der Waals

radii r_v,min: Me, 1.715; CF₃, 2.107; SiMe₃, 2.60⁸) resulted in

complete loss of the aforementioned line-broadening in the

temperature range from 213 to 328 K in the 1D NMR

spectra.

To answer the question whether the inhibition of the

dynamic behavior of 1-oCF₃was solely a steric effect of the

ortho-CF₃group or a combination of steric and electronic

properties, a CF₃group was introduced in the para-position

to nitrogen (1-pCF₃). Even though 1-pCF₃could not be

obtained in pure form, the chloro/bromo mixture showed a

slight shift of the dynamic process to higher temperatures

(T₀= 243 K, T_c= 303 K) but almost identical activation

parameters compared to 1, underlining that the decelerating

effect of the CF₃group in the ortho-position is mainly steric

in nature. A comparison of the activation parameters of

1-Me and 1-Me₂showed that a substituent in the para-

position does have a significant influence, indicating that

electron-releasing groups accelerate the dynamic behavior.

We propose that in the case of 1-Me the steric (decelerating,

more crowded) and electronic (accelerating, more electron-

releasing) effects cancel out each other, leading to almost no

difference in the dynamics between 1 and 1-Me.

Influence of the Halide. To test the influence of the halide in

this system, a 1-pCF₃NMR sample was transformed into the

bromo compound Br-1-pCF₃by abstracting the halide with

silver tetrafluoroborate (AgBF₄; 1.1 equiv) and further

reaction with LiBr. The successful exchange was proven by

³¹P NMR spectroscopy. The VT measurements were re-

peated after filtration, and the obtained activation para-

meters and temperatures (T₀; T_c) were identical within the

(8) Charton, M. J. Am. Chem. Soc. 1975, 97, 1552.

6388 Organometallics, Vol. 28, No. 22, 2009

Bru€ck and Ruhland

Table 2. KIE Data for the Fluctuation in 1-Me-d₃and 1-COD-d₂(measurement uncertainty of k values is (8%)

temperature [K]

233

<2

243

8

39

0.2

16

53

0.30

253

263

273

283

293

303

313

328

1-Me (k_H) [Hz]

1-Me-d₃(k_D) [Hz]

k_H/k_D

k₁[Hz]

k_1-COD-d2[Hz]^a

k₁/k_1-cod-d2

43

91

0.48

86

141

0.60

101

181

0.56

198

250

200

336

0.60

388

513

345

613

0.56

633

907

681

1031

0.66

1304

1591

1294

1777

0.73

2469

2939

2283

2903

0.79

4444

4999

3902

4824

0.81

7617

8325

12

<0.16

<2

12

<0.17

0.79

0.76

0.73

0.82

0.84

0.89

0.91

^aDeuteration grade about 75%; ²H NMR VT series provided in the Supporting Information.

The pyridyl-nitrogen was also labeled with ¹⁵N, but no

KIE was found by complete line-shape analysis. (It must be

stated that a ^14/15N KIE may be too small to be detected,

especially in the case of an asymmetric and bent transition

Scheme 6

state concerning the X-N Y moiety; reported ^14/15N

3 3 3

KIEs are in the range 0.994 to 1.003, which is smaller than

our measurement uncertainty. In nucleophilic addition reac-

tions, an inverse KIE is attributed to a late transition state of

the nitrogen’s lone pair nucleophilic attack resulting from

contributions of an equilibrium isotopic effect when chan-

ging from an sp²to an sp³carbon center.¹⁰) At no tempera-

tures (higher than 173 K) was a ¹J-coupling observed

approximately 85%) did not affect the rate of the dynamic

behavior, although a slightly lower T_c(290 K) was obtained

(deuterium scrambling was not observed in a CDCl₃solution

over a period of approximately 2 weeks). A comparison of

the rate constants k_Hand k_Dis presented in Table 2. T₀of

1-Me-d₃(223 K) is 10 K lower than for 1-Me (233 K), and

thus the value of the inverse kinetic isotope effect is lowest for

low temperatures.

between the ¹⁵N nucleus and the ¹⁰³Rh nucleus (³J_RhN

=

2.7 Hz). The chemical shift of the pyridyl-nitrogen in 1-

Me₂-¹⁵N (-65.8 ppm) was temperature-independent down

to 173 K and indicated that no interaction of the free lone

pair with a Lewis acid (i.e., the Rh center) occurs (Figure 4a).

In contrast if the cationic compound [1-Me₂-¹⁵N][BF₄] is

generated by addition of AgBF₄, a ¹J_RhN(¹J_RhN=11.9 Hz)

is detected and the chemical ¹⁵N-shift (-135.1 ppm) is in a

range typically found for protonated or Rh-coordinated

pyridyl moieties.¹¹Thus, by ¹⁵N labeling of the pyridyl-

nitrogen, we must state that no evidence for an interaction

of the pyridyl-nitrogen with the metal center can be detected

in the neutral complexes.

We additionally determined the T₁relaxation times

(inversion recovery) of the protons in 1-Me₂-¹⁵N and 1-

Me₂at high and low temperatures in the range with and

without the fluxional behavior present on the spectral NMR

time scale. The results along with the activation energies of

molecular motion determined by a ln(T₁) vs 1/T plot for each

proton are given in the Supporting Information.

The origin of an inverse KIE can be referred to sterics

(deuterium is slightly smaller than protium) and electronics

(deuterium is slightly more electron-donating than protium;

also a hybridization change of a C-H/Dbondduring the rate-

determining step causing a decrease of the p-amount in the

hybrid orbital is more favorable for protium than it is for

deuterium and vice versa). The stronger þI effect of the CD₃

group in comparison to a CH₃group (making the pyridyl

nitrogen more nucleophilic) and its smaller size (making the

pyridyl nitrogen more accessible) would explain the inverse

KIE found for 1-Me-d₃. Of course, the same effect would

influence 1-d₁in the same way, but since secondary KIEs are

additive, the change of only one protium into deuterium does

not seem to induce a difference in the nonlabeled compound.

One might also argue that in 1 the small ortho-H-substituent is

not yet in a critical steric level. Thus, reducing its size by

changing to deuterium will have no accelerating effect. Deu-

teration of one of the two olefinic protons of the coordinated

COD ligand also resulted in an inverse KIE almost as large as

that found for 1-Me-d₃, again supporting the additive char-

acter of a secondary KIE. Since a change of protium to

deuterium in 1-d₁did not show any KIE, we propose that

the secondary KIE in 1-COD-d₂is not caused by sterics but

due to a change of the hybridization of the olefinic C-H/D

bond in the rate-determining step with an increase in p

character. This would be an indicator for the mechanistic

interpretation that during the dynamic process some of the

coordinated olefinic COD carbons change in the rate-deter-

mining step from sp^2þx(coordinated) to sp³hybridization.⁹

The following observations can be highlighted concerning

these measurements:

• In the low-temperature range without visible line broad-

ening in the spectra, no difference is found in the T₁times

between the two compounds.

• In the high-temperature range below 373 K, 1-Me₂-¹⁵N

shows significantly smaller T₁times than 1-Me₂(most

pronounced for CH_COD, CH_p; intermediate for CH_o, Me_a,

CH_iPr; much less pronounced for Me_iPr, CH₂, Me_b), an effect

(10) Kohen, A.; Limbach, H.-H. Isotope Effects in Chemistry and

Biology; CRC Press, 2006; p 908.

(11) (a) Carlton, L.; Weber, R. Inorg. Chem. 1996, 35, 5843. (b) Meji,

R.; Stufkens, D. J.; Vrieze, K. J. Organomet. Chem. 1979, 164, 353. (c)

Bose, K. S.; Abbott, E. H. Inorg. Chem. 1977, 16, 3190. (d) Appleton, T. G.;

Cox, M. R. Magn. Reson. Chem. 1991, 29, 80. (e) Rentsch, G. H.;

Kozminski, W.; Philipsborn, W.; Asaro, F.; Pellizer, G. Magn. Reson. Chem.

1997, 35, 904. (f) Heaton, B. T.; Jacob, C.; Heggie, W.; Page, P. R.; Villax, I.

Magn. Reson. Chem. 1991, 29, 21. (g) Dilworth, J. R.; Donavan-Mtunzi, S.;

Kann, C. T.; Richards, R. I. Inorg. Chim. Acta 1981, 53, 161. (h) Carlton, L.;

Belciug, M.-P. J. Organomet. Chem. 1989, 378, 469. (i) Appleton, T. G.;

Hall, J. R.; Ralph, S. F. Inorg. Chem. 1988, 27, 4435. (j) Preetz, W.; Peters,

G.; Vogt, J.-U. Z. Naturforsch. 1993, 48b, 348.

(9) (a) Kohen, A.; Limbach, H.-H. Isotope Effects in Chemistry and

Biology; CRC Press, 2006; p 956. (b) Hoffmann, R. W. Aufkla€rung von

Reaktionsmechanismen; Thieme Verlag, 1976; p 74. (c) Krumbiegel, P.

Isotopeneffekte; Akademie-Verlag, 1970; p 131.

Article

Organometallics, Vol. 28, No. 22, 2009 6389

Figure 4. ¹⁵N{¹H} NMR spectra at 298 K of (a) 1-Me₂-¹⁵N and (b) [1-Me₂-¹⁵N]BF₄.

significantly lower T₁times are measured for 1-Me₂-¹⁵N

compared to 1-Me₂at 363, 368, and 373 K concerning

especially the CH_COD, CH_p, and the Me_aprotons. We

propose that there is a relationship between the bending

mode in Figure 5 and the isotopic effect found for the T₁

times. Through the bending, the COD-olefinic protons and

the Me_aprotons come closer together, giving rise to more

efficient relaxation via ¹H_dipole-¹H_dipoleinteraction. Thus, a

longer lifetime of the bent mode depicted in Figure 5 in

1-Me₂-¹⁵N would explain the experimental data, although it

does not help to decide whether the inducing interaction is

between the nitrogen and the metal center or between the

nitrogen and the coordinated COD double bond.

Figure 5. (A) Main rotation axis in 1-Me₂about C_py-P with

proton H_pon it. (B) In the case of an interaction of the pyridyl-

nitrogen with the metal center or a coordinated double bond of

the COD, H_pis bent out of the main rotation axis.

Influence of the Heterocyclic Fragment. The substitution of

the heterocycle to N-methylimidazole (3-Me) slowed down

the dynamic process, so that at room temperature two broad

singlets for the olefinic groups were obtained and the

exchange of the olefin sites was frozen out at 263 K (T₀)

in CDCl₃. At lower temperatures (T < 223 K) a second

dynamic process was observed, which was further investi-

gated by changing the solvent to CD₂Cl₂(Figure 6). We

ascribe the first fluxional process at higher temperatures to

freezing out the rotation about the Rh-P axis (thus, this

rotation occurs more easily in the imidazyl complexes than in

the pyridyl ones), while the second fluxional process of the

imidazyl derivatives is due to freezing out the rotation about

the P-C_imidazylbond.

that disappears at temperatures above 373 K. (We note that

the T₁values of CH_COD,cisand CH_COD,transin the low-

temperature range are almost equal. Thus, we conclude that

a mixing of the two T₁times caused by the dynamic exchange

in the high-temperature range will not perturb the data.)

• A plot of ln(T₁) vs 1/T (the slope of which is a measure of

the activation energy of molecular motion) results in excel-

lent straight lines over the complete temperature range for

1-Me₂, while in contrast for 1-Me₂-¹⁵N in the case of the

CH_COD, CH_p, CH_o, and Me_aprotons two separate straight

lines must reasonably be fitted for the high- and low-

temperature range, respectively.

VT ¹³C{¹H} measurements showed the same behavior for

the carbon nuclei; for example, the olefinic sites cis to

phosphorus were obtained at 173 K as two doublets around

69 ppm and the olefinc sites trans to phosphorus at 104 ppm

as an unresolved multiplet. The diverse signals could be as-

signed by 2D HC-COSY measurements at 213 and 173 K.

The phosphorus signal in the ³¹P{¹H} NMR spectra again

• The T₁relaxation time of H_pis by far the longest of all

protons in both compounds. On the other hand the increase

of T₁with increasing temperature is by far least pronounced

for H_pin comparison to all other protons.

We draw the following conclusions from these experi-

mental results:

• The significantly longer relaxation time of H_pis attrib-

uted to the fact that this proton (as the only one) is positioned

on a main rotational axis of the molecule 1-Me₂(rotation of

the pyridine moiety about the C_Py-P axis), and thus, it

experiences less magnetic fluxionality than the other protons

do (Figure 5).

remained unaffected by the temperature (21.4 ppm, ¹J_PRh

=

142.7 Hz). The relatively high activation temperatures (T₀=

263 K; T_cg 328 K) for the COD olefin exchange process

(>263 K) in CDCl₃also resulted in decisively larger activa-

tion enthalpies (ΔH^q= 60.9 kJ/mol) compared to 1 (ΔΔH^q=

16.3 kJ/mol). The determined activation parameters for

the second fluxional process below 223 K are approximately

10 kJ/mol lower than for the first dynamic process and are

thus in accordance with the VT NMR profile. The benzimi-

dazole derivative 4 showed a similar behavior in the VT

NMR measurements to that found for 3-Me. The sterically

more demanding isopropyl group (3-ⁱPr) had a greater influ-

ence on the dynamic VT NMR profile than the benzannulated

phenyl ring in derivative 4. In this case both fluxional

processes intersected in the temperature range from 233 to

253 K in CDCl₃(see Supporting Information for the VT

The less intense increase of T₁for the H_pproton with the

temperature compared to that of the T₁values of all other

protons in 1-Me₂can be regarded as an indicator (but not a

proof) that a bending of the pyridyl moiety occurs out of the

main rotation axis. We propose that this behavior results

from an interaction of the pyridyl nitrogen either with the

metal center or with a coordinated COD double bond.

• In 1-Me₂-¹⁵N an isotopic effect must be present concern-

ing the T₁relaxation behavior in the high-temperature range,

where the fluxionality is observed for the COD ligand, since

6390 Organometallics, Vol. 28, No. 22, 2009

Bru€ck and Ruhland

Figure 6. ¹H VT NMR series of 3-Me in CD₂Cl₂in the temperature range from 173 to 303 K.

Table 3. Activation Parameters of codRhClⁱPr₂P-Imidazyl Derivatives

solvent

ΔH^q[kJ/mol]

ΔS^q[J/(mol K)]

E_a[kJ/mol]

T₀[K]^a

T_c[K]^b

COD Exchange Process

3-Me

3-ⁱPr

CDCl₃

60.9 ( 2.0

49.5 ( 0.6

-24.0 ( 191

-25.4 ( 196

61.5 ( 1.3

50.1 ( 0.4

263

253

g328

313

4

CDCl₃

58.6 ( 4.2

-11.5 ( 83

59.4 ( 3.4

263

>328

Ligand Rotation

3-Me

3-ⁱPr

4

CD₂Cl₂

50.9 ( 6.2

48.6 ( 3.5

57.0 ( 8.4

48.8 ( 167

-27.8 ( 181

72.0 ( 156

52.3 ( 6.1

50.5 ( 15.1

58.6 ( 8.4

<173

183

e173

203

218

203

^aT₀: first temperature without line-broadening. ^bT_c: coalescence temperature.

NMR spectra). This overall behavior is also reflected by the

activation enthalpies, which are slightly lower for the second

dynamic process at lower temperatures (Table 3).

besides various NOE cross-peaks. The acquired 2D spec-

trum in CD₂Cl₂at 183 K (d₁= 2.2s; τ_m= 1s) showed slightly

less intense exchange cross-peaks and therefore a reduced

exchange rate at 183 K. ¹H,¹H-COSY measurements

assured that scalar couplings did not interfere with the

exchange cross-peaks. In general, rate constants of exchange

processes can be estimated by variation of the mixing time τ_m

and fitting of the obtained cross-peak (a_cross) to diagonal-

peak (a_diag) amplitude ratios to the equation tanh(kτ_m) ≈

(a_cross/a_diag), valid for small mixing times.

Phase-Sensitive 2D Exchange-Spectroscopy Studies.¹²We

used ¹H-¹H EXSY measurements to test our complexes for

olefin exchange processes outside the range of line-broad-

ening in 1D NMR, i.e., 1 at 213 K (and 183 K) and the

“static” complexes 1-oCF₃and 1-TMS at 298 K. To this

purpose, the spin-lattice relaxation times T₁were first

determined to set the evolution time d₁in the EXSY mea-

surements to 4 times T₁.

By this method an exchange rate of 0.88 s^-1at 213 K was

determined for complex 1, which is in accordance with the

kinetic data obtained from the 1D NMR measurements

(k₁= 0.99 s^-1by calculation using the activation parameters

ΔH^qand ΔS^qat 213 K; Figure 7). The ortho-substituted

complexes 1-TMS and 1-oCF₃also showed exchange cross-

peaks in the EXSY spectra at room temperature.

When complex 1 was measured at 213 K in CDCl₃with an

evolution time d₁of 2.2 s and a mixing time τ_mof 1 s,

exchange cross-peaks for the olefin sites were obtained

(12) (a) Levitt, M. H., Spin Dynamics; Wiley and Sons, 2001; p 500.

(b) Perrin, C. L.; Dwyer, T. J. Chem. Rev. 1990, 90, 935.

Article

Organometallics, Vol. 28, No. 22, 2009 6391

There are only slight differences between the structures of

1 and 1-PPhⁱPr₂. No hint for an interaction between the

pyridyl nitrogen and the Rh metal center or the coordinated

COD is found by X-ray analysis. The structures of a mole-

cule in the solid state of 2 and 4 deviate decisively from those

found for 1 and 1-PPhⁱPr₂. In both first mentioned molecules

the nitrogen atom prone to an interaction with the metal

center is even pointed away from it. In 2 this can be judged by

evaluation of the bond lengths. In regard to the thermo-

dynamic ground state of these molecules an attractive inter-

action of the Lewis-basic nitrogen with the metal center is not

found. There is some indication of an intermolecular inter-

action between the pyridyl nitrogen and the coordinated

COD in 2 insofar as the pyridyl nitrogen is exclusively found

in a position directed toward one of the coordinated COD

double bonds of a neighboring molecule. The anisotropic

ellipsoids for this part of the COD are decisively larger than

for the remaining portion of the ligand, and they are decisi-

vely larger than found in any other structure presented in

this paper. A similar intermolecular equilibrium was pos-

tulated in low-temperature experiments of dichloro-η²-

ethylenepyridineplatinum(II) with an excess of pyridine. In

these NMR experiments, pyridine attacks intermolecularly

the coordinated ethylene moiety to form up to 40% σ

complex at 223 K in solution.¹⁹Still, there is no abnormally

short distance found between these nitrogens and the COD

double bond with the more extended anisotropic ellipsoids

(and the dynamic behavior of 2 found in solution is concen-

tration-independent as for all other complexes).

Figure 7. Quantitative evaluation of the ¹H,¹H-EXSY mea-

surement with 1 (at 213 K), 1-TMS (at 298 K), and 1-oCF₃

(at 298 K).

The exchange rate of 0.59 s^-1for 1-TMS at 298 K is lower

than for 1 at 213 K, as expected by the 1D VT NMR

measurements (no line broadening up to 328 K). The bulky

and electron-withdrawing CF₃group in 1-oCF₃with 0.13 s^-1

led to a further deceleration of the olefin exchange rate.

Despite the bulkiness of these groups, the general accelerat-

ing effect of the nitrogen within the ring was still perceivable

compared to the unsubstituted non-nitrogen-containing

phenyl derivative.¹³

The abstraction of the chloride in 1 with AgBF₄led to the

cationic complex 1-BF₄, which is static on the spectral NMR

time scale according to the 1D ¹H NMR spectra. However,

the 2D EXSY spectra showed an exchange of the olefin sites,

which can be explained by the weak coordination and de-

and recoordination of the nitrogen to the rhodium center

in the unfavorable four-membered ring system. Addi-

tionally, an intermolecular exchange with chloro-1,5-

cyclooctadienerhodium(I) dimer (if added in traces) was

observed. Such dynamic processes were reported earlier in

similar Rh(I) complexes by Pregosin et al.²¹Addition of

CODRhCl dimer to a NMR sample of 1 also showed an

intermolecular exchange between the neutral complexes and

the dimer. As this is not directly connected to the solution

dynamics of the pure neutral complexes, no further attempts

were undertaken to provide insight into these intermolecular

processes.

Crystal Structure Determination. Single crystals for X-ray

diffraction were obtained for the complexes 1, 1-Me, 1-Me₂,

1-oCF₃, Ir-1, 2, and a bromo-chloro (Br/Cl = 1:2) mixture of

1-pCF₃and 4 from saturated dichloromethane or acetone

solutions (see Experimental Section for details). Selected

data are provided in the Supporting Information (Table 7,

Supporting Information II). This table also contains the

corresponding data for the two non-nitrogen-containing

complexes (COD)RhCl(PPh₃) (1-PPh₃, taken from the

literature¹⁴) and (COD)RhCl(PPhⁱPr₂) (1-PPhⁱPr₂, deter-

mined by us¹³).

Mechanistic Considerations. We first list a summary of the

experimental results.

•

Blocking the pyridyl nitrogen by protonation or

(even more rigorous) by exchange of the nitrogen through

a CH moiety drastically slows the dynamic process. Thus, the

nitrogen is the origin of the acceleration.

•

The addition of 1 equiv of pyridine to a sample of 1-

PPh(iPr)₂results in no line-broadening of the NMR spectra.

Therefore the intramolecular fixation of the nitrogen is

crucial for the induction of the fluctuation. (For 1-PPh₃with

5 equiv of pyridine a slight line broadening was observed, but

not comparable to 2.)

•

The dynamic process is first order in the complexes

(concentration-independent kinetics).

ortho-Substituents at the pyridyl moiety have a strong

•

steric and a significant electronic influence on the fluctua-

tion. The more sterically demanding the substituent, the

slower the fluctuation. The more electron-donating the

substituent, the faster the fluctuation.

•

Polar coordinating solvents change the mechanism

toward the temporary dissociation of the halide.

The cationic complex 1-BF₄shows a decisively slower

•

COD fluctuation than found for 1.

• Excess halide does not influence the dynamic behavior.

• Excess diene does not influence the dynamic behavior.

• Excess P-ligand does not influence the dynamic behavior

(13) Paper in preparation.

(14) Horn, Q. L.; Jones, D. S.; Evans, R. N.; Ogle, C. A.; Masterman,

T. C. Acta Crystallogr. 2002, E58, m51–m52.

(15) (a) Perera, S. D.; Shaw, B. L. J. Chem. Soc., Dalton Trans. 1995,

633. (b) Crociani, B.; Antonaroli, S.; Di Vona, M. L.; Licoccia, S. J.

Organomet. Chem. 2001, 631, 117. (c) Valentini, M.; Selvakumar, K.;

1

(no line-broadening either in H or in ³¹P NMR spectro-

scopy).

•

No evidence for an interaction of the pyridyl-nitrogen

with the metal center was found through X-ray analysis. ¹⁵N

NMR spectroscopy provides no evidence for a N Rh or

€

Worle, M.; Pregosin, P. S. J. Organomet. Chem. 1999, 587, 244. (d)

3 3 3

Bookham, J. L.; Smithies, D. M.; Pett, M. T. J. Chem. Soc., Dalton Trans.

2000, 975. (e) Mikhel, I. S.; R€uegger, H.; Butti, P.; Camponovo, F.; Huber, D.;

Mezzetti, A. Organometallics 2008, 27, 2937. (f) Espinet, P.; Casares, J. A.

Fluxional Organometallic and Coordination Compounds; John Wiley &

Sons, 2004; p 131.

N

CdC contact through visible coupling. However, T₁

3 3 3

relaxation measurements indicate that a pyridyl/complex

interaction, related to the dynamic behavior of the

COD ligand, exists that is connected with a bending of the

6392 Organometallics, Vol. 28, No. 22, 2009

Bru€ck and Ruhland

Figure 8. Depiction of a molecule in the solid state of 1, 2, and 4.

Scheme 7

pyridylphosphane ligand. The strength of the attractive part

of it can be estimated to be about 4 kJ/mol (comparison of

activation energies of molecular motion determined by T₁

measurement with the temperature of H_pand H_oin the

pyridyl moiety).

• Deuterium labeling at the coordinated olefinic C-H/D

groups in COD supports a change of hybridization of this

bond in the rate-determining step from lower to higher

p-character (inverse KIE).

On the other hand there is only one known example of an

intramolecular four-membered-ring formation in neutral

complexes bearing pyridyl phosphanes,¹⁷although the tem-

porary coordination of the pyridyl nitrogen to the metal

center (pathway B) was suspected as intermediate in some

cases (without experimental evidence though).

At first, we must state that on the basis of ground-

state criteria (X-ray analysis, NMR coupling constants) no

evidence can be found for either interaction. The exten-

ded anisotropic ellipsoids and the direction of the pyridyl

nitrogens found by X-ray analysis are not pronounced

enough to serve as unequivocal proof of an interaction

between the nitrogen and the coordinated double bond.

We still have the kinetic data that must conform to the real

mechanism.

•

COD.

The dynamic process is faster for NBD than it is for

˚

• A Ph₂P(Py) ligand (Rh-P bond length 2.2871(8) A in the

solid state) in comparison to a ⁱPr₂P(Py) ligand (Rh-P bond

length 2.3203(16) A in the solid state) decisively accelerates

the fluctuation.

˚

•

A change of the heterocyclic moiety from pyridyl to

• An activation enthalpy of about 50 kJ/mol and a slightly

negative activation entropy were found. This will be

addressed in the DFT calculations in the next section.

• No ¹⁵N-KIE was found that would be out of the range

0.99 < KIE < 1.01 (measurement uncertainty).

imidazyl slows the dynamic process of the diene. Addition-

ally, a second fluxional behavior is found at lower tempera-

tures. The rotation about the Rh-P axis is easier for

ⁱPr₂P(imidazyl) than it is for Pr₂P(Py). The latter is static

i

on the spectral NMR time scale even at room temperature

concerning the rotation about this axis.

• An inverse KIE was found in the case of deuteration of

the olefinic protons in 1.

• The T₁-relaxation behavior especially of the para-proton

in the pyridyl ring shows peculiarities. Thus, for the first time

an indirect experimental criterion can be established for an

additional interaction of the pyridyl moiety with the complex

Evaluation of Mechanisms. We concentrate on two parti-

cularly interesting mechanisms shown in Scheme 7. Pathway

B might seem to be the most intuitive one, while the novel

pathway A has yet to be considered.

Both of them are quite similar to each other. Still pathway

A (if real) would be of fundamental interest since, in contrast

to pathway B, the COD ligand is activated, which might play

a yet unconsidered role when applying pyridyl phosphanes

as a ligand in catalysis. A single similar behavior (attack of

pyridyl nitrogen on coordinated olefin) has been mentioned

before with a Pt^II(ethen) complex.¹⁹

(16) Rotondo, E.; Battaglia, G.; Arena, C. G.; Faraone, F. J.

Organomet. Chem. 1991, 419, 399.

(17) Olmstead, M. M.; Maisonhat, A.; Farr, J. P.; Balch, A. L. Inorg.

Chem. 1981, 20, 4060.

(18) Hawkes, K. J.; Cavell, K. J.; Yates, B. F. Organometallics 2008,

27, 4758.

(19) Kaplan, P. D.; Schmidt, P.; Orchin, M. J. Am. Chem. Soc. 1968,

90, 4175.

Article

Organometallics, Vol. 28, No. 22, 2009 6393

Figure 9. Depiction of a molecule of 1-CdO in the solid state,

determined by X-ray analysis.

Figure 11. Calculated geometries of the coordinated double

bond trans to the Cl ligand for the transition state (left) and

the ground state (right) of 1 in comparison to the coordinated

double bond trans to the P ligand (middle), which is almost the

same in both cases.

metal center due to the additional coordination of the

pyridyl-nitrogen leading to a more pronounced back-bond-

ing into the π* orbital of the coordinated double bond of the

COD trans to the Cl ligand, thus yielding in an interaction

closer to a metallacyclopropane for this double bond. This is

supported by the calculated geometries (Figure 11).

An elongation of the coordinated double bond trans to the

Cl ligand is found along with a shortening of the M-C bonds

and a stronger pyramidalization (which means hybridization

toward sp³) of the carbon centers in this double bond in the

transition state compared to the calculated ground state. The

coordinated double bond trans to the P ligand is almost

uneffected.

Figure 10. Calculated geometry for the transition state of path-

way B with 1.

rather than just suspecting it. The strength of its attractive

part can even be estimated using this new method.

The calculated values of ΔH^#= 55.8 kJ/mol and ΔS^#=

-41.1 J/(mol K) for this case are in good agreement with the

measured ones.

To find clear evidence for the interaction proposed in

pathway A, compound 1-CdO was synthesized with the aim

to trap and detect the interaction between the pyridyl nitro-

gen and, in this case, the electron-poor double bond (Michael

interaction, Figure 9).

Calculated transition states involving an intramolecular

attack of the coordinated COD by the pyridyl nitrogen

resulted in activation energies 3 times as large as the ones

found experimentally and can, thus, be neglected. A pathway

with a pseudotetrahedral transition state and without a

Rh-N interaction resulted in a calculated activation enthal-

py twice as large as found experimentally (about 95 kJ/mol).

Conclusion. We can prove that the most intuitive mechan-

ism, namely, the temporary coordination of the pyridyl

nitrogen in a transition state, is the reason for the induced

dynamic behavior of the coordinated COD ligand in the

complexes of this work. We could exclude a competitive

mechanism concerning an interaction of the pyridyl nitrogen

with the coordinated COD. We could also, for the first time,

find indirect experimental evidence of the pyridyl/metal

interaction using the temperature-dependence of the T₁

relaxation times of the para hydrogen in the pyridyl moiety

as a diagnostic criterion, and we can use this method to

estimate the strength of the attractive portion of this inter-

action.

1-CdO is completely static on the ¹H NMR time scale, but

its X-ray structure does not provide the anticipated proof for

the proposed interaction, which means in this case a measur-

able intramolecular Micheal-type interaction of the pyri-

dyl nitrogen with the electron-poor CdC-double bond (the

complex analogous to 1-CO with a CH group instead of the

nitrogen behaves statically, too).

DFT Calculations. DFT calculations using B3PW91/

LanL2DZ were performed. The structure parameters calcu-

lated for 1 and 1-PPh(iPr)₂were in good agreement with

those determined by X-ray analysis. (We know that this does

not allow us to tell whether calculated energies are accurate

as well.)

No ground-state structure could be found that contains

the pyridyl nitrogen coordinated to Rh. On this basis we

exclude a coordination/decoordination equilibrium pre-

ceded by the rotation of the COD ligand. The geometry

calculated for the transition state of pathway B is shown in

Figure 10.

Experimental Section

In the case of 1 a normal ¹⁵N KIE of 1.0002 and an inverse

²H KIE of 0.99 for 1-COD-d₂were calculated for this path-

way and transition state, both in qualitative accordance with

the experimental results. In particular the small calculated

¹⁵N KIE value supports that despite the formation/cleavage

of a metal;N bond in the rate-determining step this effect is

not large enough to be detectable by our measurements. The

General Procedures. Manipulations and experiments were

performed under an argon atmosphere using standard Schlenk

techniques and/or in an argon-filled glovebox if not otherwise

stated. Diethyl ether, pentane, acetonitrile, dichloromethane,

and toluene were dried and degassed using a two-column drying

system (MBraun) and stored under an argon atmosphere over

molecular sieves. Deuterated solvents used in NMR studies,

including CDCl₃, toluene-d₈, and benzene-d₆were stored under

2

inverse H KIE can be explained by a more electron-rich

6394 Organometallics, Vol. 28, No. 22, 2009

Bru€ck and Ruhland

argon over molecular sieves. Carbon monoxide 2.5 was pur-

chased from Messer Griessheim and used without further

purification. Metal precursors, RhCl₃hydrate and IrCl₃

exchange functional in combination with the correlation func-

tional of Perdew and Wang (B3PW91). Geometry calculations

and frequency calculations were performed using the valence

double-ζ LANL2DZ basis set.

3

hydrate from Strem Chemicals were used as received. Chloro-

diisopropylphosphane, chlorodiphenylphosphine, ¹⁵NH₄Cl,

COD, NBD, 2-Br-pyridine, imidazole, n-butyllithium (2.5 M

hexanes), sec-butyllithium (1.3 M hexane/benzene), tert-butyl-

lithium (1.6 M heptane), 2-bromo-4-trifluoromethylpyridine, 2-

bromo-6-trifluoromethylpyridine, 2,6-dibromopyridine, tri-

methylsilyl chloride, deuterium oxide, and trideuteromethyl

iodide were purchased from Aldrich and used without further

purification.

General Procedure for the Synthesis of 2-Pyridylphosphines

Starting from 2-Bromopyridines (except L1-TMS). To a stirred,

cold (-78 °C; 2-propanol þ dry ice) solution of 1 equiv of

2-bromopyridine in diethyl ether (approximately 10 mL/

2.5 mmol) was added 1 equiv of a 1.6 M n-butyllithium solution

in n-pentane. After stirring the mixture for 30 min (if not

mentioned otherwise; see experimental data of the ligand),

i

1 equiv of R₂PCl (R = Pr, Ph) was added via syringe. The

NMR measurement was performed on a Bruker AMX400:

¹H NMR (7.24 ppm, 400 MHz) and ¹³C NMR (77.0 ppm, 100

MHz). Chemical shifts are given in ppm relative to the solvent

signal for CDCl₃/C₆D₆/C₇D₈. ³¹P NMR (161 MHz) used 85%

H₃PO₄as an external standard, and ¹⁵N NMR (40.54 Hz) used

¹⁵N-urea in DMSO-d₆at -304.3 ppm as external standard. The

FTIR spectra were measured on a JASCO FI7IR-460plus

spectrometer using KBr pellets or in a KBr cell as a CH₂Cl₂

solution.

reaction mixture was allowed to warm slowly to room temper-

atur overnight. Removing the solvent under vacuum resulted in

a white suspension. The product was separated from inorganic

salts by extracting and cannula-filtering with n-pentane. Re-

moving the solvent yielded the ligand as a colorless to yellowish

liquid. The ligands were used without further purification.

1

Diisopropyl-2-pyridylphosphine (L1). Yield: 93%. H NMR

(CDCl₃, 298 K): 0.91 (dd, ³J_HH= 6.9 Hz, ³J_HP= 12.0 Hz, 6H,

CHCH₃), 1.11 (dd, J_HH= 7.2 Hz, J_HP= 14.6 Hz, 6H,

3

Dibromo-1,5-cyclooctadiene,²²2,6-cyclooctadienone,²³and

2-bromo-6-methylpyridine²⁴were synthesized according to lit-

erature procedures. The 2-bromopyridine derivatives were

synthesized by procedures described in the Supporting Informa-

tion.

3

2

CHCH₃), 2.26 (dsept, J_HH= 8.5 Hz, J_HP= 2.8 Hz, 2H,

CHCH₃), 7.14-7.18 (m, 1H, CH_Py), 7.47-7.50 (m, 1H, CH_Py),

=

7.56 (tt, ³J_HH= 8.5 Hz, J = 1.9 Hz, 1H, CH_Py), 8.68 (d, ³J_HH

4.8 Hz, 1H, NCH). ³¹P{¹H} NMR (CDCl₃, 298 K): 15.0 (s).

2

¹³C{¹H} NMR (CDCl₃, 298 K): 19.3 (d, J_CP= 9.9 Hz,

CHCH₃), 19.6 (d, J_CP= 16.0 Hz, CHCH₃), 23.1 (d, J_CP=

2

1

VT-NMR Calibration and Evaluation. The temperature con-

trol unit of the NMR machine was calibrated with a sample of

1,2-ethanediol.²⁵The line-broadening was quantified using the

program suite DNMR7.1²⁶as described in the literature cita-

tion. The olefinic COD signals were fitted as an AB system

(W_a= W_b= 12 Hz, %a = 50).

DFT Calculations. The DFT calculations were performed

using the program suite Gaussian 03.²⁷All molecular geometries

were fully optimized. Transition states were obtained using the

OPT2 or OPT3 function implemented in the program suite and

were proven to be one-dimensional saddle points by frequency

analysis in each case. KIEs were calculated by employing the

X(iso=n) function, implemented in the program suite. The

DFT method used includes Becke’s three-parameter hybrid

2

11.1 Hz, CHCH₃), 122.5 (s, CH_Py), 130.9 (d, J_CP= 33.3 Hz,

PCCH_Py), 134.6 (d, ³J_CP= 8.6 Hz, CH_Py), 150.0 (d, ³J_CP= 6.2

Hz, NCH), 161.9 (d, ¹J_CP= 14.8 Hz, CP_Py).

Diisopropyl-3-deutero-2-pyridylphosphine (D-L1). Yield: 84%.

¹H NMR (CDCl₃, 298 K): 0.91 (dd, ³J_HH= 6.8 Hz, ³J_HP= 11.7

Hz, 6H, CHCH₃), 1.10 (dd, ³J_HH= 7.4 Hz, ³J_HH= 14.7 Hz, 6H,

CH₃), 2.22-2.31 (m, 2H, CHCH₃), 7.15 (d, ³J_HH= 7.4 Hz, 1H,

CH_Py), 7.47 - 7.50 (m, 1H, CH_Py), 7.57 (t, ³J_HH= 7.5 Hz, 1H,

CH_Py) [residual oH: 8.68 (d, ³J_HH= 4.7 Hz, 0.14H)]. ²H NMR

(CDCl₃, 298 K): 8.71 (s, NCD). ¹³C{¹H} NMR (CDCl₃, 298 K):

2

19.3 (d, J_CP= 9.2 Hz, CHCH₃), 19.6 (d, J_CP= 16.5 Hz,

CHCH₃), 23.1 (d, J_CP= 11.0 Hz, CHCH₃), 122.4 (s, CH_Py),

1

2

130.9 (d, J_CP= 33.1 Hz, PCCH_Py), 134.6 (d, J_CP= 9.2 Hz,

3

CH_Py), 149.9 (d, ³J_CP= 5.5 Hz, residual-NCH), 161.7 (d, ²J_CP

=

12.9 Hz, CP_Py). CD was not detected. ³¹P{¹H} NMR (CDCl₃,

298 K): 15.0 (s).

Diisopropyl-(6-methyl-2-pyridyl)phosphine (L1-Me). Yield: 83%.

(20) Phillips, A. D.; Bolano, S.; Bosquain, S. S.; Daran, J.-C.;

Malacea, R.; Peruzzini, M.; Poli, R.; Gonsalvi, L. Organometallics

2006, 25, 2189.

¹H NMR (CDCl₃, 298 K): 0.92 (dd, J_HH= 6.2 Hz, J_HP

=

3

€

(21) Filipuzzi, S.; Mannel, E.; Pregosin, P. S.; Albinati, A.; Rizzato, S.

Organometallics 2008, 27, 4580.

(22) Detert, H.; Rose, B.; Mayer, W.; Meier, H. Chem. Ber. 1994, 127,

1529.

(23) Echter, T.; Meier, H. Chem. Ber. 1985, 118, 182.

(24) Schubert, U. S.; Eschbaumer, C.; Heller, M. Org. Lett. 2000, 2,

3373.

(25) (a) van Geet, A. L. Anal. Chem. 1970, 42, 670. (b) Friebolin, H.;

Schilling, G.; Pohl, L. Org. Magn. Reson. 1979, 12, 569. (c) Piccinni-

Leopardii, C.; Fabre, O.; Reisse, J. Org. Magn. Reson. 1976, 8, 233. (d)

11.1 Hz, 6H, CHCH₃), 1.10 (dd, ³J_HH= 6.2 Hz, ³J_HP= 13.5 Hz,

6H, CHCH₃), 2.19-2.28 (m, 2H, CHCH₃), 2.53 (s, 3H, CH_3;Py),

6.99 (d, J_HH= 7.4 Hz, 1H, CH_Py), 7.26 (d, J_HH= 4.9 Hz,

3

1H, CH_Py), 7.44 (t, J_HH= 7.4 Hz, 1H, CH_Py). ³¹P{¹H} NMR

3

(CDCl₃, 298 K): 12.8 (s). ¹³C{¹H} NMR (CDCl₃, 298 K):

19.4 (d, J_CP= 9.9 Hz, CHCH₃), 19.6 (d, J_CP= 17.3 Hz,

2

1

CHCH₃), 23.1 (d, J_CP= 12.3 Hz, CHCH₃), 24.8 (s, CH_3;Py),

2

120.0 (s, CH_Py), 127.2 (d, J_CP= 28.4 Hz, PCCH_Py), 134.6

€

Kohler, F. H.; Xie, X. Magn. Reson. Chem. 1997, 35, 487. (e) Raiford, D. S.;

3

(d, J_CP= 7.4 Hz, CH_Py), 158.3 (d, J_CP= 7.4 Hz, CCH₃),

3

Fisk, C. L.; Becker, E. D. Anal. Chem. 1979, 51 (12), 2050.

161.1 (d, ¹J_CP= 8.6 Hz, CP_Py).

Diisopropyl-(6-trideuteromethyl-2-pyridyl)phosphine (D₃-L1-

(26) http://www.chem.wisc.edu/areas/reich/plt/windnmr.htm.

(27) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;

Robb, M. A.; Cheeseman, J. R.; Montgomery, J. A., Jr.; Vreven, T.;

Kudin, K. N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.;

Barone, V.; Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson,

G. A.; Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.;

Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai,

H.; Klene, M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Bakken,

V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev,

O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.;

Morokuma, K.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Zakr-

zewski, V. G.; Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas, O.;

Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.;

Ortiz, J. V.; Cui, Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.; Stefanov,

B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.;

Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.;

Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong, M. W.;

Gonzalez, C.; Pople, J. A. Gaussian 03, revision B.01; Gaussian, Inc.:

Wallingford, CT, 2004.

Me). Yield: 75%. ¹H NMR (CDCl_3,298 K): 0.92 (dd, ³J_HH

=

6.8 Hz, ³J_HP= 12.1 Hz, 6H, CHCH₃), 1.10 (dd, ³J_HH= 7.1 Hz,

³J_HP= 14.2 Hz, 6H, CHCH₃), 2.24 (dhept, ³J_HH= 7.1, ²J_HP

=

2.8 Hz, 2H, CHCH₃), 6.99 (dt, J_HH= 1.3 Hz, ³J_HH= 7.6 Hz,

1H, CH_Py), 7.26 (dt, J_HH= 1.3 Hz, J = 3.8 Hz, 1H, CH_Py), 7.44

(dt, ³J_HH= 7.6 Hz, J = 1.8 Hz, 1H). ²H NMR (CDCl₃, 298 K):

2.51 (s). ¹³C{¹H} NMR (CDCl₃, 298 K): 19.4 (d, J_CP= 10.3

2

Hz, CHCH₃), 19.6 (d, ²J_CP= 16.1 Hz, CHCH₃₂), 23.1 (d, ¹J_CP

=

11.7 Hz, CHCH₃), 120.0 (s, CH_Py), 127.2 (d, J_CP= 28.6 Hz,

PCCH_Py), 134.6 (d, ³J_CP₁= 8.1 Hz, CH_Py), 158.3 (d, ³J_CP= 8.8

Hz, CCH₃), 161.1 (d, J_CP= 8.8 Hz, CP_Py). CD₃was not

detected. ³¹P{¹H} NMR (CDCl₃, 298 K): 13.9 (s).

Diisopropyl-(6-trifluoromethyl-2-pyridyl)phosphine (L1-oCF₃).

The reaction mixture was stirred for 15 min after addition of

Article

Organometallics, Vol. 28, No. 22, 2009 6395

n-BuLi. Yield: 65%. ¹H NMR (CDCl₃, 298 K): 0.92 (dd, ³J_HH

= 6.8 Hz, ³J_HP= 11.7 Hz, 6H, CHCH₃), 1.10 (dd, ³J_HH= 7.4

Hz, ³J_HP= 14.7 Hz, 6H, CH₃), 2.32 (dhept, ³J_HH= 7.4 Hz, ³J_HP

solvent under vacuum resulted in a white suspension. The

product was separated from inorganic salts by extracting and

cannula-filtering with n-pentane. Removing the solvent yielded

the ligand as a colorless to yellowish liquid. The ligands were

used without further purification.

3

= 2.4 Hz, 2H, CHCH₃), 7.53 (d, J_HH= 7.4 Hz, 1H, CH_Py),

7.64 (m, 1H, CH_Py), 7.73 (t, ³J_HH= 8.0 Hz, 1H, CH_Py). ³¹P{¹H}

NMR (CDCl₃, 298 K): 15.6 (s). ¹³C{¹H} NMR (CDCl₃, 298 K):

19.1 (d, J_CP= 9.5 Hz, CHCH₃), 19.4 (d, J_CP= 16.1 Hz,

N-Methyl-2-imidazyldiisopropylphosphine (L3-Me). Yield:

2

3

84%. ¹H NMR (CDCl₃, 298 K): 0.93 (dd, J_HH= 7.4 Hz,

CHCH₃), 23.0 (d, ¹J_CP= 11.0 Hz, CHCH₃), 118.9 (q, ³J_CF

2.4 Hz, CH_Py), 118.9 (q, ¹J_CF= 274.4 Hz, CF₃) 133.2 (d, ²J_CP

=

³J_HP= 12.3 Hz, 6H, CHCH₃), 1.06 (dd, ³J_HH= 7.4 Hz, ³J_HP

=

15.9 Hz, 6H, CHCH₃), 2.25-2.34 (m, 2H, CHCH₃), 3.78 (s, 3H,

NCH₃), 6.93 (s, 1H, CH_imid), 7.17 (s, 1H, CH_imid). ³¹P{¹H}

NMR (CDCl_3,298 K): -19.3 (s). ¹³C{¹H} NMR (CDCl_3,298

K): 19.2 (d, ²J_CP= 7.4 Hz, CHCH₃), 19.9 (d, ²J_CP= 17.3 Hz,

33.4 Hz, PCCH_Py), 135.6 (d, ³J_CP= 8.8 Hz, CH_Py), 148.2 (dq,

²J_CF= 4.4 Hz, ³J_CP= 34.4 Hz, CCF₃), 163.6 (d, ²J_CP= 18.3

Hz, CP). ¹⁹F{¹H} NMR (CDCl₃, 293 K): -69.3 (s).

1

3

Diisopropyl-(4-trifluoromethyl-2-pyridyl)phosphine (L1-pCF₃).

The reaction mixture was stirred for 15 min after addition

of n-BuLi. The product was not pure. Yield: ca. 58%. ¹H

CHCH₃), 24.2 (d, J_CP= 11.1 Hz, CHCH₃), 33.9 (d, J_CP=

14.8 Hz, NCH₃), 122.6 (s, CH_imid), 130.6 (s, CH_imid), 146.4

(d, ¹J_CP= 14.8 Hz, PC_imid).

3

NMR (CDCl₃, 298 K): 0.95 (dd, J_HH= 7.0 Hz, ³J_HP= 11.9

N-Isopropyl-2-imidazyldiisopropylphosphine (L3-ⁱPr). Yield:

Hz, 6H, CHCH₃), 1.16 (dd, ³J_HH= 7.1 Hz, ³J_HP= 14.7 Hz, 6H,

62%. ¹H NMR (CDCl₃, 298 K): 0.93 (dd, J_HH= 7.4 Hz,

3

2

3

CHCH₃), 2.35 (dhept, J_HP= 2.3 Hz, J_HH= 7.1 Hz, 2H,

CHCH₃), 7.42 (d, ³J_HH= 5.1 Hz, 1H, HCCF₃), 7.72 (d, J = 4.3

²J_HP= 12.3 Hz, 6H, PCHCH₃), 0.93 (dd, J_HH= 7.4 Hz,

²J_HP= 15.9 Hz, 6H, CHCH₃), (d, J_HH= 6.1 Hz, 6H,

3

Hz, 1H, HCCP), 8.92 (d, J_HH= 5.1 Hz, 1H, NCH). ³¹P{¹H}

NCHCH₃), 2.26-2.35 (m, 2H, PCHCH₃), 5.05-5.14 (m, 1H,

NCHCH₃), 7.05 (s, 1H, CH_imid), 7.21 (s, CH_imid). ³¹P{¹H} NMR

(CDCl₃, 298 K): -19.5 (s). ¹³C{¹H} NMR (CDCl₃, 298 K):

NMR (CDCl₃, 298 K): 16.7 (s). ¹³C{¹H} NMR (CDCl₃, 298 K):

19.2 (d, J_CP= 9.5 Hz, CHCH₃), 19.4 (d, J_CP= 16.1 Hz,

2

CHCH₃), 23.2 (d, ¹J_CP= 11.7 Hz, CHCH₃), 117.9 (br d, ³J_CF

3.7 Hz, CH_Py), 122.9 (q, J_CF= 273.7 Hz, CF₃) 125.8 (dq,

=

19.4 (d, J_CP= 9.9 Hz, PCHCH₃), 20.0 (d, J_CP= 17.3 Hz,

2

1

PCHCH₃), 23.9 (s, NCHCH₃), 24.4 (d, J_CP= 4.9 Hz, PCH-

³J_CF= 3.4 Hz, ²J_CP= 35.1 Hz, PCCH_Py), 137.1 (dq, ²J_CF

=

1

CH₃), 47.8 (d, J_CP= 17.3 Hz, NCHCH₃), 116.8 (s, CH_imid),

8.8 Hz, ³J_CP= 34.4 Hz, CCF₃), 150.5 (d, ³J_CP= 4.4 Hz, CH_Py),

163.5 (d, ²J_CP= 23.4 Hz, CP). ¹⁹F{¹H} NMR (CDCl₃, 293 K):

-65.9 (s).

130.6 (s, CH_imid), 145.3 (d, ¹J_CP= 12.3 Hz, CP_imid).

N-Methyl-2-methylbenzimidazyldiisopropylphosphine (L4).

1

Yield: 67%. H NMR (CDCl₃, 298 K): 0.98 (dd, J_HH= 6.8

3

Diphenyl-2-pyridylphosphine (L2). Off-white solid. Yield:

Hz, J_HP= 12.9 Hz, 6H, CHCH₃), 1.12 (dd, J_HH= 7.4 Hz,

³J_HP= 15.9 Hz, 6H, CHCH₃), 2.42-2.50 (m, 2H, CHCH₃),

3.93 (s, 3H, NCH₃), 7.21-7.27 (m, 2H, CH_imid), 7.31-7.34 (s,

1H, CH_imid), 7.79-7.82 (m, 1H, CH_imid). ³¹P{¹H} NMR

(CDCl₃, 298 K): -13.5 (s). ¹³C{¹H} NMR (CDCl₃, 298 K):

1

2

55%. H NMR (CDCl₃, 298 K): 7.05 (d, J_HH= 8.6 Hz, 1H,

CH_Py), 7.15 (m, 1H, CH_Py), 7.31-7.39 (m, 10H, CH_Ph), 7.53 (m,

1H, CH_Py), 8.70 (d, ²J_HH= 4.9 Hz, 1H, NCH_Py). ³¹P{¹H} NMR

(CDCl₃, 298 K): -3.9 (s). ¹³C{¹H} NMR (CDCl₃, 298 K): 122.1

(s, CH_Py), 127.8 (d, ¹J_CP= 14.7 Hz, PC_Ph), 128.6 (d, ²J_CP= 7.4

Hz, CH_Py), 129.0 (s, CH_Ph), 134.1 (s, CH_Ph), 134.3 (s, CH_Ph),

2

19.5 (d, J_CP= 8.6 Hz, CHCH₃), 19.9 (d, J_CP= 18.1 Hz,

CHCH₃), 24.2 (d, ¹J_CP= 7.8 Hz, CHCH₃), 31.2 (d, ³J_CP= 16.4

Hz, NCH₃), 109.5 (s, CH_imid), 119.9 (s, CH_imid), 122.0 (s,

CH_imid), 122.6 (s, CH_imid), 136.4 (s, NC), 144.1 (s, NC), 154.7

(d, ¹J_CP= 19.8 Hz, PC_imid).

3

2

135.7 (d, J_CP= 1.8 Hz, CH_Py), 136.1 (d, J_CP= 11.3 Hz,

CH_Ph), 150.3 (d, ²J_CP= 12.8 Hz, CH_Py), 164.0 (d, ²J_CP= 12.8

Hz, CH_Py).

Diisopropyl-(6-trimethylsilyl-2-pyridyl)phosphine (L1-TMS).

To a stirred, cold (-78 °C; 2-propanol þ dry ice) solution of

1.63 mL (2.61 mmol) of a 1.6 M tert-butyllithium solution (in n-

petane) in approximately 8 mL of diethyl ether was added

dropwise a solution of 0.3 g (1.30 mmol) of 2-bromo-

6-(trimethylsilyl)pyridine in 2 mL of diethyl ether via syringe.

The resulting clear and yellowish solution was stirred for 3 h at

-78 °C, followed by addition of 0.21 mL (1.30 mmol) of

chlorodiisopropylphosphine via syringe. The reaction mixture

was allowed to warm slowly to room temperature overnight.

After removing the solvent under vacuum, the product was

extracted with n-pentane (3 ꢀ 8 mL). Removal of the solvent

under vacuum yielded the product as light yellow liquid (0.31 g;

89%). The ligand was used without further purification. ¹H

NMR (CDCl₃, 298 K): 0.27 (s with Si-sat., ²J_HSi= 40.5 Hz, 9H,

SiCH₃), 0.90 (dd, ³J_HH= 6.7 Hz, ³J_HP= 11.7 Hz, 6H, CHCH₃),

1.10 (dd, ³J_HH= 7.4 Hz, ³J_HP= 14.7 Hz, 6H, CH₃), 2.25-2.40

(m, 2H, CHCH₃), 7.32-7.36 (m, 2H, CH_Py), 7.41-7.45 (m, 1H,

CH_Py). ³¹P{¹H} NMR (CDCl₃, 298 K): 13.1 (s). ¹³C{¹H} NMR

4,6-Dimethyl-1H-pyridin-2-one. 4,6-Dimethylpyrone (2.7 g,

21.7 mmol), 2.1 g (38.3 mmol) of ammonium chloride, and

1.7 g (30.3 mmol) of potassium hydroxide in a 20 mL Schlenk

tube were suspended in 10 mL of water, sealed, and heated at

100 °C for 5 days. After cooling, the water phase was washed

3ꢀ with 20 mL of ethyl acetate. The combined organic phases

were dried over magnesium sulfate and filtered, and the solvent

was removed in vacuo. The crude product was purified over

a short silica gel column (EtOAc/methanol = 9:1; R_f= 0.5) to

yield 0.77 g (14-19%) of the product as a beige solid. ¹H NMR

(CDCl₃): 2.19 (s, 3H, CH₃), 2.25 (s, 3H, CH₃), 5.84 (s, 1H,

CH_Py), 6.13 (s, 1H, CH_Py), 13.10 (br s, 1H, NH). ¹³C{¹H} NMR

(298 K, CDCl₃): 18.8 (s, CH₃), 21.5 (s, CH₃), 108.5 (s, CH_Py),

115.1 (s, CH_Py), 144.6 (s, CCH₃), 153.6 (s, NCCH₃), 165.9

(s, CO).

¹⁵N-4,6-Dimethyl-1H-pyridin-2-one. ¹H NMR(298 K, CDCl₃):

2.14 (s, 3H, CH₃), 2.28 (s, 3H, CH₃), 5.89 (s, 1H, CH_Py), 6.18

(s, 1H, CH_Py), 12.91 (br s, 1H, NH). ¹³C{¹H} NMR (298 K,

CDCl₃): 18.8 (s, CH₃), 21.5 (s, CH₃), 108.6 (s, CH_Py), 115.1 (d,

²J_CN= 5.1 Hz, CH_Py), 144.6 (d, ¹J_CN= 11.7 Hz, NCCH₃), 153.7

2

(CDCl₃, 298 K): -1.9 (s, SiCH₃), 19.0 (d, J_CP= 8.8 Hz,

CHCH₃), 19.6 (d, J_CP= 16.8 Hz, CHCH₃), 22.8 (d, J_CP=

2

1

(s, CCH₃), 165.9 (d, J_CN= 11.7 Hz, CO). ¹⁵N NMR (298 K,

2

10.3 Hz, CHCH₃), 126.8 (s, CH_Py), 129.9 (d, J_CP= 38.1 Hz,

PCCH), 160.9 (d, ³J_CP= 11.7 Hz, CP), 168.2 (d, ³J_CP= 3.7 Hz,

CSiCH₃).

CDCl₃): -206.7 (s).

Trifluoromethanesulfonic Acid (4,6-Dimethyl-2-pyridyl) Ester.

Trifluoromethanesulfonic anhydride (1.1 mL, 1.86 g; 6.6 mmol)

was added dropwise to a cold (ice bath) solution of 0.74 g

(6.0 mmol) of 2,4-dimethyl-1H-pyridone in 5 mL of dry pyr-

idine. The mixture was allowed to warm slowly overnight and

stirred for an additional 48 h at RT. Excess pyridine was

removed in vacuo, and the residue was dissolved in dichloro-

methane and filtered over a short silica gel column (R_f= 0.78).

Removal of the solvent in vacuo yielded the product as yellowish

liquid (0.77 g; 50%). ¹H NMR (CDCl₃): 2.36 (s, 3H, CH₃),

General Procedure for the Synthesis of N-Alkyl-2-imidazyl-

phosphines. To a stirred, cold (-78 °C; 2-propanol þ dry ice)

solution of 1equiv of N-alkylimidazole in diethyl ether

(approximately 10 mL/2.5 mmol) was added 1 equiv of a

1.6 M solution of n-butyllithium. The mixture was stirred for

1 h at this temperature followed by addition of 1 equiv of chloro-

diisopropylphosphine. The reaction mixture was allowed to

warm slowly to room temperature overnight. Removing the

6396 Organometallics, Vol. 28, No. 22, 2009

Bru€ck and Ruhland

2.47 (s, 3H, o-CH₃), 6.76 (s, 1H, CH_py), 7.01 (s, 1H, CH_py).

¹³C{¹H} NMR (CDCl₃): 20.9 (s, CH₃), 23.6 (s, CH₃), 112.3 (s,

CH_Py), 118.6 (q, ¹J_CF= 320.5 Hz, CF₃), 124.3 (s, CH_Py), 153.0

(s, CCH₃), 155.5 (s, NCCH₃), 158.3 (s, CO). ¹⁹F NMR (CDCl₃):

-74.2 (s). EI-MS (m/z): 255.0 (M, correct isotope pattern, 69%),

227.0 (34%), 161.9 (F₃CSO₃CH, 42%), 147.9 (12%), 107 (M þ

H^þ- F₃CSO₃, 7%), 106 (M - F₃CSO₃, 38%), 106 (M -

F₃CSO₃H, 100%), 103.9 (M - F₃CSO₃H - H^þ,69%), 93.9

(64%), 77.9 (46%), 68.9 (60%), 52.9 (79%), 38.9 (18%).

24.7 (s, CH_3;Py), 25.4 (s, CH_3;P2y), 125.3 (d, J_CP= 8.9 Hz, CH_Py),

127.3 (dd, J_CN= 7.4 Hz, J_CP= 16.3 Hz, PCCH_Py), 146.9

2

(d, ³J_CP= 5.9 Hz, CCH₃), 153.8 (d, ¹J_CP= 112.9 Hz, CP), 158.2

(d, ³J_CP=17.8Hz, NCCH₃). ³¹P{¹H} NMR (CDCl₃, 298 K): 50.1

2

(d, J_PN= 28.4 Hz). ¹⁵N{¹H} NMR (CDCl₃, 298 K): -73.5

(d, ²J_NP= 28.4 Hz). EI-MS (m/z): 198.0 (M - ⁱPr, 23%), 154.9

[M - (ⁱPr)₂, correct isotope pattern, 100%], 150.0 (15%), 107.9

(M - PO(ⁱPr)₂, 14%).

Diisopropyl-(4,6-dimethyl-2-pyridyl)phosphine. Trichlorosilane

(0.7 mL, 0.94 g; 6.93 mmol) was added dropwise to 0.33 g

(1.36 mmol) of 2-(diisopropylphosphinoyl)-4,6-dimethylpyri-

dine in ca. 20 mL of xylene (mixture of isomers) and ca. 4 mL

(ca. 7.0 mmol) of triethylamine in a 150 mL Schlenk tube.

This resulted in immediate formation of a white precipitate.

The mixture was first stirred for 1 h at RT and then slowly (1 h)

heated to 135 °C for 14 h. After cooling, the mixture was filtered

over a silica gel column and the column washed 5ꢀ with a

1:0.5 mixture of dichloromethane/triethylamine. The solvent

was removed in vacuo, yielding the product as a colorless liquid

¹⁵N-Trifluoromethanesulfonic Acid (4,6-Dimethyl-2-pyridyl)

1

Ester. H NMR (CDCl₃): 2.36 (s, 3H, CH₃), 2.47 (d, J_NH

3

=

3.6 Hz, 3H, o-CH₃), 6.76 (s, 1H, CH_Py), 7.01 (s, 1H, CH_Py).

¹³C{¹H} NMR (CDCl₃): 20.9 (s, CH₃), 23.6 (d, ²J_CN= 3.6 Hz,

o-CH₃), 112.3 (s, CH_Py), 118.6 (q, ¹J_CF= 319.8 Hz, CF₃), 124.7

(s, CH_Py), 153.0 (s, CCH₃), 155.5 (d, ¹J_CN= 8.9 Hz, NCCH₃),

158.3 (s, CO). ¹⁹F NMR (CDCl₃): -74.2 (s). ¹⁵N NMR

(CDCl₃): -98.8 (s). EI-MS (m/z): 256.0 (M, correct isotope

pattern, 73%), 228.0 (35%), 162.9 (F₃CSO₃CH, 44%), 148.9

(12%), 108.0 (M þ H^þ- F₃CSO₃, 7%), 107.0 (M - F₃CSO₃,

36%), 105.9 (M - F₃CSO₃H, 100%), 104.9 (M - F₃CSO₃H -

H^þ, 70%), 94.9 (64%), 78.0 (41%), 68.9 (60%), 52.9 (80%),

38.9 (18%).

Diisopropylphosphine Oxide. Diisopropylphosphine (2.1 mL,

2 g, 13.1 mmol) was dissolved in 30 mL of acetonitrile and 2 mL

of water. The solution was refluxed for 4 h, dried with magne-

sium sulfate, and filtered, and the solvent was removed in vacuo.

The liquid was destilled over a Kugelrohr still, yielding 1.4 g

(86%) of the product at 0.1 mbar and 100 °C as a colorless

liquid. The product was presumed to be hygroscopic and stored

1

3

(66%). H NMR (298 K, CDCl₃): 0.91 (dd, J_HH= 7.4 Hz,

=

³J_HP= 12.5 Hz, 6H, CHCH₃), 1.09 (dd, ³J_HH= 6.7 Hz, ³J_HP

14.1 Hz, 6H, CHCH₃), 2.17-2.25 (m, 2H, CHCH₃), 2.25 (s, 3H,

CH_3-Py), 2.48 (s, 3H, NCCH_3-Py), 6.83 (s, 1H, NCCH_Py), 7.09 (s,

=

1H, PCCH_Py). ¹³C{¹H} NMR (298 K, CDCl₃): 19.4 (d, ²J_CP

2

8.9 Hz, CHCH₃), 19.7 (d, J_CP= 17.8 Hz, CHCH₃), 20.9 (s,

CHCH₃), 23.1 (s, CHCH₃), 23.2 (s, CH_3-Py), 24.5 (s, NCCH₃),

123.1 (s, NCCH_Py), 128.1 (d, J_CP= 29.7 Hz, PCCH_Py), 146.9

2

(d, ³J_CP= 8.9 Hz, NCCH₃), 153.8 (d, ¹J_CP= 8.9 Hz, CP), 158.2

2

(d, J_CP= 8.9 Hz, NCCH₃). ³¹P{¹H} NMR (298 K, CDCl₃):

13.3 (s).

1

3

under argon. H NMR (CDCl₃, 298 K): 1.27 (dd, J_HH= 7.1

3

Hz, J_HP= 15.0 Hz, 6H, CHCH₃), 1.31 (dd, J_HH= 7.1 Hz,

³J_HP= 13.0 Hz, 6H, CHCH₃), 2.08-2.16 (m, 2H, CHCH₃),

¹⁵N-Diisopropyl-(4,6-dimethyl-2-pyridyl)phosphine. ¹H NMR

(298 K, CDCl₃): 0.91 (dd, ³J_HH= 6.7 Hz, ³J_HP= 11.6 Hz, 6H,

6.41 (dt, J_HH= 3.2 Hz, ¹J_HP= 449.3 Hz, 1H, PH). ¹³C{¹H}

CHCH₃), 1.09 (dd, J_HH= 7.4 Hz, J_HP= 13.5 Hz, 6H,

CHCH₃), 2.17-2.25 (m, 2H, CHCH₃), 2.25 (s, 3H, CH_3-Py),

2.48 (d, ³J_HN= 2.4 Hz, 3H, NCCH_3-Py), 6.83 (s, 1H, NCCH_Py),

7.08 (d, ³J_HN= 2.4 Hz, 1H, PCCH_Py). ¹³C{¹H} NMR (298 K,

CDCl₃): 19.4 (d, ²J_CP= 8.9 Hz, CHCH₃), 19.7 (d, ²J_CP= 17.8

Hz, CHCH₃), 20.9 (s, CHCH₃), 23.1 (s, CHCH₃), 23.2 (s, CH_3;

3

NMR (CDCl₃, 298 K): 14.9 (d, ²J_CP= 3.7 Hz, CHCH₃), 16.2 (s,

CHCH₃), 25.0 (d, J_CP= 64.4 Hz, CHCH₃). ³¹P{¹H} NMR

(CDCl₃, 298 K): 56.3 (s).

1

2-(Diisopropylphosphinoyl)-4,6-dimethylpyridine. Trifluoro-

methanesulfonic acid (4,6-dimethyl-2-pyridyl) ester (0.68 g,

2.66 mmol), 0.39 g (2.93 mmol) of diisopropylphosphine oxide,

0.12 g (0.53 mmol) of palladiumacetate, and 0.24 g (5.59 mmol)

of 1,4-bisphenylphosphinobutane (dppb) were suspended in ca.

25 mL of dry dimethylsulfoxide and 4.4 mL (26.6. mmol) of N,

N-diisopropylethylamine in a Schlenk tube and heated at 130 °C

for 2.5 days. After cooling, the solvent was removed in vacuo, the

residue was dissolved in 20 mL of dichloromethane and washed

twice with 5 mL of water, and the organic phase was subse-

quently dried over magnesium sulfate. The solvent was removed

after filtration and the brown-black residue was distilled over

a Kugelrohr still . The product was isolated at 160 °C and ca. 1 ꢀ

10^-1mbar as a yellowish, viscous liquid (0.38 g; 61%). ¹H NMR

2

_Py), 24.5 (d, J_CP= 8.9 Hz, NCCH₃), 123.1 (d, J = 8.9 Hz,

NCCH_Py), 128.3 (d, ²J_CP= 29.7 Hz, PCCH_Py), 145.3 (d, ³J_CP

=

5.9 Hz, NCCH₃), 153.0 (d, ¹J_CP= 6.0 Hz, CP), 160.5 (br s, NC-

CH₃). ³¹P{¹H} NMR (298 K, CDCl₃): 12.1 (d, ²J_PN= 21.7 Hz).

¹⁵N{¹H} NMR (298 K, CDCl₃): -65.3 (d, ²J_NP= 21.7 Hz).

General Procedure for the Synthesis of CODMCl(P-N) (1-4;

M = Rh, Ir). In a 50 mL Schlenk flask, 1 equiv of (CODMCl)₂

and 2.2 equiv of the N-P ligand were dissolved in dichloro-

methane and stirred for 1 h at room temperature. After removal

of the solvent in vacuo, the yellow powders were washed with

n-pentane (3ꢀ) and dried in vacuo.

Chlorocycloocta-1,5-diene(diisopropyl-2-pyridylphosphine)-

rhodium(I) (1). Yellow powder (95%). 1 can be crystallized

overnight from a saturated acetone solution. ¹H NMR

3

(CDCl₃, 298): 1.04 (dd, J_HH= 7.4 Hz, J_HP= 15.9 Hz, 6H,

3

CHCH₃), 1.17 (dd, J_HH= 6.8 Hz, J_HP= 15.3 Hz, 6H,

CHCH₃), 2.32 (s, 3H, CH_3;Py), 2.42-2.48 (m, 2H, CH), 2.48

(s, 3H, CH_3;Py), 6.98 (s, 1H, CH_Py), 7.68 (d, J = 4.9 Hz, 1H,

3

(CDCl₃, 293 K): 1.20 (dd, J_HH= 7.4 Hz, J_HP= 13.5 Hz,

3

6H, CHCH₃), 1.49 (dd, J_HH= 7.4 Hz, J_HP= 15.9 Hz, 6H,

CHCH₃), 1.89 (br d, J = 8.6 Hz, 4H, CHH’), 2.30 (br d, J = 9.8

CH_Py). ¹³C{¹H} NMR (CDCl₃, 298): 15.0 (d, J_PC= 4.8 Hz,

2

CHCH₃), 16.1 (d, J_PC= 4.8 Hz, CHCH₃), 20.8 (s, CHCH₃),

Hz, 4H, CHH’), 2.68-2.78 (m, 2H, CHCH₃), 7.22 (d, ³J_HH

=

3

24.3 (s, CHCH₃), 24.7 (s, CH_3;Py), 25.3 (s, CH_3;Py), 125.4 (d, J_CP

= 3.0 Hz, CH_Py), 127.3 (d, J_CP= 16.7 Hz, PCCH_Py), 146.9

5.5 Hz, 1H, CH_Py), 7.52 (d, J_HH= 7.4 Hz, 1H, CH_Py),

7.61-7.66 (m, 1H, CH_Py), 8.67 (d, ³J_HH= 3.7 Hz, 1H, NCH_Py).

¹H NMR (CDCl₃, 213 K): 1.16 (dd, ³J_HH= 6.8 Hz, ³J_HP= 14.1

Hz, 6H, CHCH₃), 1.43 (dd, ³J_HH= 7.4 Hz, ³J_HP= 14.7 Hz, 6H,

CHCH₃), 1.76-1.81 (m, 2H, CHH⁰_cisCP), 1.90-1.93 (m, 2H,

CHH⁰_transCP), 2.26 (br d, J = 7.4 Hz, 4H, CHH⁰), 2.60 - 2.70 (m,

2H, CHCH₃), 3.33 (s, 2H, CH_COD;cisCP), 5.23 (s, 2H, CH_COD;

_transCP), 7.25 (d, ³J_HH= 6.1 Hz, 1H, CH_Py), 7.49 (d, ³J_HH= 7.4

Hz, 1H, CH_Py), 7.64-7.69 (m, 1H, CH_Py), 8.66 (d, ³J_HH= 4.9

Hz, 1H, NCH_Py). ¹³C{¹H} NMR (CDCl₃, 293 K): 19.3

2

(d, ³J_CP= 7.9 Hz, CCH₃), 153.8 (d, ¹J_CP= 111.2 Hz, CP), 158.2

3

(d, J_CP= 18.7 Hz, NCCH₃). ³¹P{¹H} NMR (CDCl₃, 298):

50.3 (s). EI-MS (m/z): 197.0 (M - ⁱPr, 22%), 153.9 [M - (ⁱPr)₂,

correct isotope pattern, 100%], 149.0 (15%), 106.9 (M - PO-

(ⁱPr)₂, 16%).

¹⁵N-2-(Diisopropylphosphanoyl)-4,6-dimethylpyridine. ¹H NMR

(CDCl₃, 298 K): 1.03 (dd, ³J_HH= 6.7 Hz, ³J_HP= 15.3 Hz, 6H,

CHCH₃), 1.17 (dd, ³J_HH= 6.7 Hz, ³J_HP= 15.3 Hz, 6H, CHCH₃),

2.31 (s, 3H, CH_3;Py), 2.38-2.48 (m, 2H, CHCH₃), 2.47 (s, 3H,

NCCH_3;Py), 6.97 (s, 1H, CH_Py), 7.67 (d, J = 4.9 Hz, 1H, CH_Py).

¹³C{¹H} NMR (CDCl₃, 298 K): 15.1 (s, CHCH₃), 16.1 (s,

(s, CHCH₃), 19.9 (d, ²J_CP= 4.4 Hz, CHCH₃), 24.2 (d, ¹J_CP

=

22.0 Hz, CHCH₃), 123.3 (d, J_CP= 1.5 Hz, CH_Py), 128.6 (d,

4

3

²J_CP= 16.1 Hz, PCCH_Py), 134.6 (d, J_CP= 5.9 Hz, CH_Py),

149.5 (d, J_CP= 11.7 Hz, NCH_Py), 155.5 (d, J_CP= 45.4 Hz,

1

3

1

CHCH₃), 20.8 (s, CHCH₃), 24.3 (d, J_CP= 8.9 Hz, CHCH₃),

Article

Organometallics, Vol. 28, No. 22, 2009 6397

CP_Py). ¹³C{¹H} NMR (CDCl₃, 213 K): 19.3 (s, CHCH₃), 19.9

(d, ²J_CP= 2.2 Hz, CHCH₃), 23.4 (d, ¹J_CP= 22.0 Hz, CHCH₃),

P 6.71. FAB-MS m/z: 420.2 (M - Cl, 100%), 347.1 (M - COD,

51%), 312.1 (M - Cl - COD, 9%).

1

28.4 (s, CH₂), 32.7 (s, CH₂), 69.5 (d, J_{CR2 h}= 13.2 Hz,

CH_COD;cisCP), 102.8 (dd, J_CRh= 11.0 Hz, J_CP= 7.3 Hz,

Chloro-1,5-cyclooctadiene-[diisopropyl-(3-trideuteromethyl-

2-pyridyl)phosphine]rhodium(I) (1-CD₃). Yellow powder (92%).

This can be crystallized from a saturated acetone solution

1

CH_COD;transCP), 123.3 (s, CH_Py), 128.6 (d, ²J_CP= 16.8 Hz, PC-

3

1

CH_Py), 134.6 (d, J_CP= 5.9 Hz, CH_Py), 149.5 (d, ³J_CP= 10.2

(yellow crystals). H NMR (CDCl₃, 293 K): 1.22 (dd, ³J_HH

=

Hz, NCH_Py), 155.5 (d, ¹J_CP= 45.4 Hz, CP_Py). ³¹P{¹H} NMR

(CDCl₃, 293 K): 43.3 (d, J_PRh= 144.7 Hz). Anal. Calcd for

6.8 Hz, ³J_HP= 14.1 Hz, 6H, CHCH₃), 1.53 (dd, ³J_HH= 7.4 Hz,

³J_HP= 15.9 Hz, 6H, CHCH₃), 1.87 (d, J = 7.4 Hz, 4H, CHH⁰),

2.28 (br s, 4H, CHH’), 2.68-2.74 (m, 2H, CHCH₃), 3.52 (vbr s,

2H, CH_COD;cisCP), 5.08 (vbr s, 2H, CH_COD;transCP), 7.04 (d,

³J_HH= 7.3 Hz, 1H, CH_Py), 7.27 (d, ³J_HH= 7.3 Hz, 1H, CH_Py),

7.49-7.52 (m, 1H, CH_Py). ¹H NMR (CDCl₃, 213 K): 1.17 (dd,

1

C₁₉H₃₀NClPRh: C 51.65, H 6.84, N 3.17, Cl 8.02, P 7.01. Found:

C 51.50, H 6.87, N 3.11, Cl 8.02, P 6.94. FAB-MS m/z:

406.2 (M^þ- Cl, 100%), 333.1 (M^þ- COD, 7.5%), 298

(M^þ- COD - Cl, 3.5%).

Chloro-1,5-cyclooctadiene[diisopropyl-(6-deutero-2-pyridyl)-

phosphine]rhodium(I) (1-d₁). Yellow powder (89%). This can be

crystallized from a saturated acetone solution (yellow-orange

crystals). Deuteration grade ≈ 85%. ¹H NMR (CDCl₃, 293 K):

1.21 (dd, ³J_HH= 6.7 Hz, ³J_HP= 14.1 Hz, 6H, CHCH₃), 1.50

(dd, ³J_HH= 7.1 Hz, ³J_HP= 15.6 Hz, 6H, CHCH₃), 2.30 (br d,

J = 8.0 Hz, 4H, CHH⁰), 2.69 (br d, J = 5.5 Hz, 4H, CHH⁰),

2.70-2.77 (m, 2H, CHCH₃), 7.21 (d, ³J_HH= 6.8 Hz, 1H, CH_Py),

7.49-7.52 (m, 1H, CH_Py), 7.61-7.66 (m, 1H, CH_Py), [residual

ortho-H: 8.67, d, J = 8.0 Hz, 0.14H)]. ¹H NMR (CDCl₃, 213 K):

1.15 (dd, ³J_HH= 6.8 Hz, ³J_HP= 14.1 Hz, 6H, CHCH₃), 1.42

(dd, ³J_HH= 6.8 Hz, ³J_HP= 15.3 Hz, 6H, CHCH₃), 1.78 (br d,

J = 8.6 Hz, 2H, CHH⁰_cisCP), 1.91 (br d, J = 9.8 Hz, 2H,

CHH⁰_transCP), 2.65 (br d, J = 4.9 Hz, 4H, CHH⁰), 3.32 (s,

CH_COD;cisCP), 5.23 (s, CH_COD;transCP), 7.25 (d, J = 8.6 Hz,

³J_HH= 7.4 Hz, ³J_HH= 13.4 Hz, 6H, CHCH₃), 1.47 (dd, ³J_HH

=

7.4 Hz, ³J_HH= 15.9 Hz, 6H, CHCH₃), 1.77 (d, J = 13.5 Hz, 2H,

CHH’_cisCP), 1.91 (d, J = 9.8 Hz, 2H, CHH⁰_transCP), 2.26 (br s,

4H, CHH⁰), 2.60-2.70 (m, 2H, CHCH₃), 3.34 (s, 2H,

CH_COD;cisCP), 5.21 (s, 2H, CH_COD;transCP), 7.06 (d, ³J_HH= 7.4

3

Hz, 1H, CH_py), 7.25 (d, J_HH= 7.4 Hz, 1H, CH_Py), 7.53 (dt,

³J_HH= 7.4 Hz, J = 2.9 Hz, 1H, CH_Py). ¹³C{¹H} NMR (CDCl₃,

293 K): 19.3 (s, CHCH₃), 19.9 (d, ²J_CP= 3.7 Hz, CHCH₃), 24.3

(d, ¹J_CP= 22.7 Hz, CHCH₃), 31.0 (vbr s, CH_allyl), 69.0 (vbr s,

CH_COD;cisCP), 102.5 (vbr s, CH_COD;transCP), 122.8 (s, CH_Py),

2

125.2 (d, J_CP= 15.4 Hz, PCCH_Py), 134.8 (d, J_CP= 5.9 Hz,

CH_Py), 154.5 (d, ¹J_CP= 46.8 Hz, CP_Py), 158.1 (d, ³J_CP= 12.4

Hz, CCD₃). ¹³C{¹H} NMR (CDCl₃, 213 K): 18.9 (s, CHCH₃),

19.3 (d, ²J_CP= 3.7 Hz, CHCH₃), 23.5 (d, ¹J_CP= 22.7 Hz, CH-

CH₃), 28.3 (s, CH_allyl), 32.5 (s, CH_allyl), 69.2 (d, ¹J_CRh= 16.6 Hz,

1

2

CH_Py), 7.50 (d, J = 7.4 Hz, CH_Py), 7.65-7.68 (m, 1H, CH_Py

)

CH_COD;transCP), 102.5 (dd, J_CRh= 10.6 Hz, J_CP= 7.0 Hz,

CH_COD;transCP), 122.7 (m, CH_Py), 124.8 (m, PCCH_Py), 134.6 (m,

CH_Py), 153.4 (d, ¹J_CP= 49.0 Hz, CP_Py), 157.7 (d, ³J_CP₁= 12.4

[residual ortho-CH: 8.66 (d, J = 3.7 Hz, 0.14H)]. ¹³C{¹H} NMR

2

(CDCl₃, 293 K): 19.2 (s, CHCH₃), 19.8 (d, J_CP= 22.1 Hz,

CHCH₃), 24.3 (d, ¹J_CP= 22.7 Hz, CHCH₃), 31.0 (br s, CH_allyl),

70.0 (br s, CH_COD;cisCP), 103.0 (br s, CH_COD;transCP), 123.2 (s,

CH_Py), 128.5 (d, ²J_CP= 18.4 Hz, PCCH_Py), 134.8 (d, ³J_CP= 6.4

Hz, CCD₃). ³¹P{¹H} NMR (CDCl₃, 293 K): 42.3 (d, J_PRh

=

144.7 Hz). ²H NMR (CDCl₃, 293 K): 2.50 (s). Anal. Calcd for

C₂₀H₂₉D₃NClPRh: C 52.35, H 7.69, N 3.05. Found: C 51.67,

H 7.32, N 2.89. FAB-MS (m/z): 423.2 (M^þ- Cl, 100%), 458.2

(M 2%).

1

3

Hz, CH_Py), 149.2 (dt, J_CD= 26.7 Hz, J_CP= 12.9 Hz, CD_Py;

overlaps with residual ortho-CH_Py: 149.5, d, ³J_CP= 12.0 Hz), 158.1

(d, ¹J_CP= 45.1 Hz, PC_Py). ³¹P{¹H} NMR (CDCl₃, 293 K): 43.4 (d,

¹J_PRh= 146.9 Hz). ²H NMR (CDCl₃, 293 K): 8.72 (s). FAB-MS

(m/z): 406.7 (100%, M - Cl, correct isotope pattern), 298.8 (2.1%,

M - Cl - COD). Anal. Calcd for C₁₉H₂₉DNClPRh: C 51.54, H

7.06, N 3.16. Found: C 51.59, H 6.65, N 3.03.

Chloro-1,5-cyclooctadiene[diisopropyl-(4,6-dimethyl-2-pyridyl)-

phosphine]rhodium(I) (1-Me₂). Yellow powder (99%). This can

be crystallized from a saturated acetone solution (yellow-orange

crystals). ¹H NMR (CDCl₃, 293 K): 1.21 (dd, ³J_HH= 6.6 Hz,

³J_PH= 14.1 Hz, 6H, CHCH₃), 1.53 (dd, ³J_HH= 7.4 Hz, ³J_PH

=

Chlorocycloocta-1,5-diene[diisopropyl-(6-methyl-2-pyridyl)-

phosphine]rhodium(I) (1-Me). Yellow powder (91%). This can

be crystallized overnight from a saturated acetone solution. ¹H

14.7 Hz, 6H, CHCH₃), 1.86 (br d, J = 8.6 Hz, 4H, CHH⁰), 2.29

(br s, 7H, CHH⁰, CH_3;Py), 2.46 (s, 3H, CH_3;Py), 2.61-2.75 (m,

2H, CHCH₃), 6.86 (s, 1H, CH_Py), 7.04 (s, 1H, CH_Py). ¹H NMR

(CDCl₃, 213 K): 1.17 (dd, ³J_HH= 6.8 Hz, ³J_HH= 14.1 Hz, 6H,

3

NMR (CDCl₃, 293 K): 1.22 (dd, J_HH= 6.7 Hz, ³J_HP= 14.1

Hz, 6H, CHCH₃), 1.54 (dd, ³J_HH= 7.4 Hz, ³J_HP= 15.9 Hz, 6H,

CHCH₃), 1.87 (d, J = 7.4 Hz, 4H, CH₂), 2.28 (d, J = 8.6 Hz, 4H,

CH₂), 2.52 (s, 3H, CH_3;Py), 2.64-2.79 (m, 2H, CHCH₃), 7.04 (d,

³J_HH= 7.4 Hz, 1H, CH_Py), 7.26 (d, ³J_HH= 7.4 Hz, 1H, CH_Py),

7.51 (dt, ³J_HH= 7.4 Hz, J = 2.5 Hz, CH_Py). ¹H NMR (CDCl₃,

213 K): 1.21 (dd, ³J_HH= 7.4 Hz, ³J_HP= 13.5 Hz, 6H, CHCH₃),

1.50 (dd, ³J_HH= 7.4 Hz, ³J_HP= 14.7 Hz, 6H, CHCH₃), 1.80 (d,

J = 11.0 Hz, 2H, CHH⁰_cisCP), 1.94 (d, J = 11.0 Hz, 2H,

CHH⁰_transCP), 2.29 (br s, 4H, CH₂), 2.55 (s, 3H, CH_3;Py), 3.38

(s, 2H, CH_COD;cisCP), 5.24 (s, 4H, CH_COD;transCP), 7.10 (d,

³J_HH= 7.4 Hz, 1H, CH_Py), 7.29 (d, ³J_HH= 7.4 Hz, 1H, CH_Py),

7.57 (t, ³J_HH= 7.4 Hz, 1H, CH_Py). ¹³C{¹H} NMR (CDCl₃, 293

K): 19.3 (s, CHCH₃), 19.9 (d, ²J_CP= 4.4 Hz, CHCH₃), 24.3 (d,

¹J_CP= 22.7 Hz, CHCH₃), 24.6 (s, CH_3;Py), 122.7 (s, CH_Py),

CHCH₃), 1.48 (dd, J_HH= 6.1 Hz, J_HH= 15.3 Hz, 6H,

CHCH₃), 1.77 (br d, J = 13.5 Hz, 2H, CHH⁰_cisCP), 1.90 (br d,

J = 12.3 Hz, 2H, CHH⁰_transCP), 2.22-2.32 (m, 4H, CHH⁰), 2.29

(s, 4H, CH_3;Py), 2.46 (s, 3H, CH_3;Py), 2.56-2.69 (m, 2H,

CHCH₃), 3.36 (br s, 2H, CH_COD;cisCP), 5.19 (br s, 2H, CH_COD;

_transCP), 6.89 (s, 1H, CH_Py), 7.01 (s, 1H, CH_Py). ¹³C{¹H} NMR

(CDCl₃, 293 K): 19.3 (s, CHCH₃), 19.9 (s, CHCH₃), 21.2 (s,

CHCH₃), 24.2 (s, CH_3-Py), 24.4 (s, CHCH₃), 24.5 (s, CH_3-Py),

30.3 (vbr s, CH₂), 69.7 (vbr s, CH_COD;cisCP), 102.2 (vbr s,

CH_COD;transCP), 123.8 (s, NCCH_Py), 125.8 (d, ²J_CP= 14.9 Hz,

3

PCCH_Py), 145.7 (d, ³J_CP= 5.9 Hz, CCH_3-Py), 154.2 (d, ¹J_CP

=

3

47.5 Hz, PC), 157.8 (d, J_CP= 14.6 Hz, NCCH₃). ¹³C{¹H}

NMR (CDCl₃, 213 K): 19.2 (s, CHCH₃), 19.5 (s, CHCH₃), 21.3

(s, CHCH₃), 23.7 (s, CH_3-Py), 23.9 (s, CHCH₃), 24.5 (s, CH_3;Py),

2

3

2

125.2 (d, J_CP= 15.4 Hz, PCCH_py), 134.8 (d, J_CP= 6.6 Hz,

CH_Py), 154.5 (d, ¹J_CP= 46.8 Hz, CP_Py), 158.1 (d, ³J_CP= 10.2

Hz, CCH_3;Py). ¹³C{¹H} NMR (CDCl₃, 213 K): 19.1 (s, CHCH₃),

28.5 (br s, CH₂), 32.7 (br s, CH₂), 69.7 (d, J_CRh= 14.9 Hz,

CH_COD;cisCP), 102.2 (pseudo-t, ¹J_CRh= 8.9 Hz, ²J_CP= 8.9 Hz,

CH_COD;transCP), 123.9 (s, NCCH_Py), 125.5 (d, ²J_CP= 14.9 Hz,

=

2

1

19.4 (d, J_CP= 3.7 Hz, CHCH₃), 23.7 (d, J_CP= 22.7 Hz,

CHCH₃), 24.7 (s, CH_3;Py), 28.4 (s, CH₂), 32.7 (s, CH₂), 69.4 (d,

PCCH_Py), 145.8 (d, ³J_CP= 5.9 Hz, CCH_3;Py), 153.4 (d, ¹J_CP

47.5 Hz, PC_Py), 157.6 (d, J_CP= 11.9 Hz, NCCH₃). ³¹P{¹H}

3

¹J_CRh= 13.9 Hz, CH_COD;cisCP), 102.2 (dd, J_CP= 8.1 Hz,

2

1

NMR (CDCl₃, 293 K): 41.1 (d, J_PRh= 145.5 Hz). FAB-MS:

¹J_CRh= 11.0 Hz, CH_COD;transCP), 122.9 (s, CH_Py), 124.9 (d,

433.6 (M - Cl, 100%, correct isotope pattern), 360.6 (M -

COD, 30%, correct isotope pattern). Anal. Calcd: C 53.68, H

7.29, N 2.98, Cl 7.55. Found: C 53.57, H 7.36, N 2.76, Cl 7.42.

¹⁵N-Chloro-1,5-cyclooctadiene[diisopropyl(4,6-dimethyl-

2-pyridyl)phosphine]rhodium(I) (1-Me₂-¹⁵N). Yellow powder

²J_CP= 15.4 Hz, PCCH_Py), 134.8 (d, J_CP= 6.6 Hz, CH_Py),

153.4 (d, J_CP= 48.3 Hz, CP_Py), 158.0 (d, J_CP= 13.2 Hz,

=

3

1

3

CCH_3-Py). ³¹P{¹H} NMR (CDCl₃, 293 K): 41.6 (d, J_PRh

1

144.7 Hz). Anal. Calcd for C₂₀H₃₂ClNPRh: C 52.7, H 7.08,

N 3.07, Cl 7.78, P 6.79. Found: C 52.63, H 7.31, N 2.96, Cl 7.82,

1

3

(99%). H NMR (CDCl₃, 293 K): 1.21 (dd, J_HH= 6.1 Hz,

6398 Organometallics, Vol. 28, No. 22, 2009

Bru€ck and Ruhland

³J_HP= 13.5 Hz, 6H, CHCH₃), 1.53 (dd, ³J_HH= 6.8 Hz, ³J_HP

=

Chlorocycloocta-1,5-diene[diisopropyl-(4-trifluoromethyl-

2-pyridyl)phosphine]rhodium(I) (1-pCF₃). ¹H NMR (CDCl₃,

298 K): 1.21 (dd, ³J_HH= 6.8 Hz, ³J_HP= 14.1 Hz, 6H, CHCH₃),

15.3 Hz, 6H, CHCH₃), 1.85 (br d, J = 7.4 Hz, 4H, CHH’), 2.29

(br s, 7H, CHH⁰, CH_3;Py), 2.46 (s, 3H, CH_3;Py), 2.62-2.73 (m,

2H, CHCH₃), 6.86 (s, 1H, CH_Py), 7.03 (s, 1H, CH_Py). ¹H NMR

(CDCl₃, 213 K): 1.16 (dd, ³J_HH= 6.8 Hz, ³J_HH= 14.1 Hz, 6H,

3

1.51 (dd, J_HH= 6.8 Hz, J_HP= 15.2 Hz, 6H, CHCH₃),

1.84-1.91 (m, 2H, CHH’_cisCP), 1.89 (d, J = 7.8 Hz, 2H,

CHH⁰_transCP), 2.25-2.32 (m, 4H, CHH’), 2.67-2.83 (m, 2H,

CHCH₃), 3.31 (vbr s, 2H, CH_COD;cisCP), 5.33 (vbr s, 2H, CH_COD;

_transCP), 7.44 (d, ³J_HH= 4.9 Hz, 1H, CH_Py), 7.67 (d, ³J_HH= 12.2

Hz, 1H, CH_Py), 8.87 (d, ³J_HH= 5.4 Hz, 1H, NCH_Py). ¹³C{¹H}

NMR (CDCl₃, 298 K): 19.2 (s, CHCH₃), 19.7 (d, ²J_CP= 3.7 Hz,

CHCH₃), 24.3 (d, ¹J_CP= 22.0 Hz, CHCH₃), 31.2 (vbr s, CH₂),

69.8 (vbr s, CH_COD;cisCP), 103.4 (v.br s, CH_COD;transCP), 118.7 (s,

3

CHCH₃), 1.47 (dd, J_HH= 6.1 Hz, J_HH= 15.3 Hz, 6H,

CHCH₃), 1.77 (br d, J = 12.3 Hz, 2H, CHH⁰_cisCP), 1.90 (br d,

J = 11.0 Hz, 2H, CHH⁰_transCP), 2.22 - 2.33 (m, 4H, CHH⁰), 2.29

(s, 4H, CH_3-Py), 2.45 (d, ³J_HN= 2.5 Hz, 3H, CH_3;Py), 2.56-2.69

(m, 2H, CHCH₃), 3.36 (br s, 2H, CH_COD;cisCP), 5.19 (br s, 2H,

CH_COD;transCP), 6.88 (s, 1H, CH_Py), 7.00 (s, 1H, CH_Py). ¹³C{¹H}

NMR (CDCl₃, 293 K): 19.3 (s, CHCH₃), 19.9 (s, CHCH₃), 21.2

(s, CHCH₃), 24.2 (s, CH_3-Py), 24.4 (s, CHCH₃, CH_3-Py), 30.8 (vbr

s, CH₂), 69.9 (vbr s, CH_COD;cisCP), 102.0 (vbr s, CH_COD;transCP),

123.8 (d, ³J = 8.9 Hz, NCCH_Py), 125.8 (m, PCCH_Py), 145.7 (s,

CCH_3-Py), 154.1 (d, ¹J_CP= 47.5 Hz, PC), 157.8 (d, ²J_CP= 11.9

Hz, NCCH₃). ¹³C{¹H} NMR (CDCl₃, 213 K): 19.2 (s, CHCH₃),

19.5 (s, CHCH₃), 21.3 (d, ¹J_CP= 8.9 Hz, CHCH₃), 23.7 (s, CH_3-

_Py), 23.9 (s, CH_3-Py), 24.4 (t, d, J = 8.9 Hz, CHCH₃), 28.5 (br s,

CH₂), 32.7 (br s, CH₂), 69.5 (d, ²J_CRh= 11.9 Hz, CH_COD;cisCP),

102.1 (br s, CH_COD;transCP), 123.9 (d, J = 5.9 Hz, NCCH_Py),

125.5 (m, PCCH_Py), 145.7 (d, ³J_CP= 5.9 Hz, CCH_3-Py), 153.2 (d,

1

3

CH_Py), 124.0 (q, J_CF= 273.7 Hz, CF₃), 123.7 (dq, J_CF

=

2

3

3.4 Hz, J_CP= 16.8 Hz, PCCH_Py), 137.1 (dq, J_CP= 6.6 Hz,

²J_CF= 34.4 Hz, CCF₃), 150.3 (d, ³J_CP= 11.7 Hz, NCH), 158.4

(d, ¹J_CP= 41.0 Hz, CP_Py). ³¹P{¹H} NMR (CDCl₃, 298 K): 44.6

(d, J_PRh= 148.5 Hz). ¹⁹F{¹H} NMR (CDCl₃, 298 K): -65.8

1

þ

(s). FAB-MS (m/z): 663.8 [RhCl(PN)₂

, 14%], 628.8

[Rh(PN)₂^þ, 22%], 508.8 (M^þ, 7%), 473.9 (M - Cl, 100%),

400.8 (M^þ- COD, 56%).

Bromoocycloocta-1,5-diene[diisopropyl-(4-trifluoromethyl-

2-pyridyl)phosphine]rhodium(I) (Br-1-pCF₃). ¹H NMR (CDCl₃,

298 K): 1.22 (dd, ³J_HH= 6.7 Hz, ³J_HP= 14.1 Hz, 6H, CHCH₃),

1.55 (dd, ³J_HH= 7.4 Hz, ³J_HP= 15.9 Hz, 6H, CHCH₃), 1.87 (br

s, 4H, CHH’), 2.27 (d, J = 8.6 Hz, 4H, CHH’), 2.76-2.85 (m,

2H, CHCH₃), 7.43 (d, ³J_HH= 4.9 Hz, 1H, CH_Py), 7.67 (s, 1H,

CH_Py), 8.87 (d, ³J_HH= 6.1 Hz, 1H, NCH_Py). ¹H NMR (CDCl₃,

213 K): 1.18 (dd, ³J_HH= 6.7 Hz, ³J_HP= 14.1 Hz, 6H, CHCH₃),

3

¹J_CP= 50.5 Hz, PC), 157.6 (d, J_CP= 14.9 Hz, NCCH₃).

1

³¹P{¹H} NMR (CDCl₃, 293 K): 40.1 (dd, J_PRh= 145.5 Hz,

²J_PN= 22.3 Hz). ¹⁵N{¹H} NMR (CDCl₃, 293 K): -65.8 (dd,

3

²J_PN= 22.3 Hz, J_RhN= 2.7 Hz). FAB-MS: 434.6 (M - Cl,

100%, correct isotope pattern), 361.6 (M - COD, 37%, correct

isotope pattern).

3

Chlorocycloocta-1,5-diene[diisopropyl-(6-trimethylsilyl-

2-pyridyl)phosphine]rhodium(I) (1-TMS). Yellow powder (86%).

1.50 (dd, J_HH= 7.4 Hz, J_HP= 15.9 Hz, 6H, CHCH₃),

1.72-1.76 (m, 2H, CHH⁰_cisCP), 1.91-1.96 (m, 2H, CHH⁰_transCP),

2.23-2.28 (m, 4H, CHH⁰), 2.69 - 2.75 (m, 2H, CHCH₃), 3.26 (s,

¹H NMR (CDCl₃, 298 K): 0.29 (s, 9H, SiCH₃), 1.20 (dd, ³J_HH

=

7.4 Hz, ³J_HP= 4.9 Hz, 6H, CHCH₃), 1.58 (dd, ³J_HH= 4.9 Hz,

³J_HP= 7.4 Hz, 6H, CHCH₃), 1.77-1.82 (m, 2H, CHH’_cisCP),

1.92-1.95 (m, 2H, CHH⁰_transCP), 2.28 (br s, 4H, CHH⁰), 2.65 -

2.75 (m, 2H, CHCH₃), 3.36 (s, 2H, CH_COD;cisCP), 5.27 (s, 2H,

CH_COD;transCP), 7.34-7.40 (m, 2H, CH_Py), 7.50-7.55 (m, 2H,

CH_Py). ¹³C{¹H} NMR (CDCl₃, 298 K): -1.9 (s with Si satellites,

¹J_CSi= 53.0 Hz, SiCH₃), 19.3 (s, CHCH₃), 20.1 (d, ¹J_CP= 3.7

Hz, CHCH₃), 24.5 (d, ¹J_CP= 22.2 Hz, CHCH₃), 28.7 (s, CH₂),

32.8 (s, CH₂), 69.2 (d, ¹J_CP= 14.8 Hz, CH_COD;cisCP), 102.5 (dd,

2H, CH_COD;cisCP), 5.38 (s, 2H, CH_COD;transCP), 7.48 (d, ³J_HH

=

4.9 Hz, 1H, CH_Py), 7.62 (s, 1H, CH_Py), 8.90 (d, ³J_HH= 4.9 Hz,

1H, NCH_Py). ¹³C{¹H} NMR (CDCl₃, 298 K): 19.4 (s, CHCH₃),

20.1 (d, J_CP= 3.7 Hz, CHCH₃), 25.2 (d, J_CP= 22.0 Hz,

2

1

3

CHCH₃), 118.7 (s, CH_Py), 123.5 (d, J_CP= 16.8 Hz, CCF₃),

1

122.7 (q, J_CF= 273.7 Hz, CF₃), 137.1 (d, J_CP= 40.5 Hz,

2

1

PCCH_Py), 150.2 (d, J_CP= 11.7 Hz, CH_Py), 158.8 (d, J_CP

=

39.5 Hz, PC_Py). ¹³C{¹H} NMR (CDCl₃, 213 K): 19.2 (s,

CHCH₃), 19.5 (s, CHCH₃), 24.5 (d, J_CP= 22.2 Hz, CH-

1

CH₃), 28.7 (s, CH₂), 32.4 (s, CH₂), 70.5 (d, J_RhC= 14.8 Hz,

²J_CP= 7.4 Hz, J_RhC= 11.1 Hz, CH_COD;transCP), 126.7 (d,

3

1

2

CH_COD;cisCP), 102.8 (dd, J_RhC= 11.1 Hz, J_CP= 6.2 Hz,

²J_CP= 14.8 Hz, PCCH_Py), 127.7 (s, CH_Py), 132.7 (d, J_CP

=

6.2 Hz, CH_Py), 155.8 (d, ¹J_CP= 46.9 Hz, CP_Py), 168.4 (d, ³J_CP

1

CH_COD;transCP), 118.9 (s, CH_arom), 122.3 (q, J_CF= 273.7 Hz,

11.1 Hz, NCSi). ³¹P{¹H} NMR (CDCl₃, 298 K): 41.6 (d, ¹J_PRh

= 144.7 Hz). ²⁹Si{¹H} NMR (CDCl₃, 298 K): -12.0 (s). Anal.

Calcd for C₂₂H₃₈NClOPRhSi: C 51.41, H 7.45, N 2.73. Found:

C 50.36, H 7.69, N 2.51. FAB-MS m/z: 513.2 (M^þ, 5%), 478.2

(M^þ- Cl, 98%), 405.1 (M^þ- Cl - TMS, 100%).

CF₃), 136.8 (d, ²J_CP= 34.5 Hz, PCCH_Py), 150.2 (d, ¹J_CP= 11.7

Hz, CH_Py), 157.7 (d, J_CP= 41.9 Hz, PC_Py). ³¹P{¹H} NMR

1

(CDCl₃, 298 K): 46.1 (d, J_PRh= 145.5 Hz). ¹⁹F{¹H} NMR

1

(CDCl₃, 298 K): -65.8 (s).

Chlorocycloocta-1,5-diene(diisopropyl-2-pyridylphosphine)-

iridium(I) (Ir-1). Yellow powder (91%). This can be crystallized

from a saturated acetone solution. ¹H NMR (CDCl₃, 298 K): 1.2

Chlorocycloocta-1,5-diene[diisopropyl-(6-trifluormethyl-

2-pyridyl)phosphine]rhodium(I) (1-oCF₃). Yellow powder (90%).

This can be crystallized overnight from a saturated acetone

solution (orange crystals). ¹H NMR (CDCl₃, 293 K): 1.22 (dd,

3

(dd, J_HH= 6.7 Hz, J_HP= 13.2 Hz, 6H, CHCH₃), 1.43 (dd,

³J_HH= 7.4 Hz, ³J_HP= 15.9 Hz, 6H, CHCH₃), 1.65 (d, J = 7.4

Hz, 4H, CHH⁰), 2.14 (d, J = 8.6 Hz, 4H, CHH⁰), 2.87-3.01 (m,

2H, CHCH₃), 7.26 (d, ³J_HH= 4.9 Hz, 1H, CH_Py), 7.60-7.62 (m,

1H, CH_Py), 7.67-7.71 (m, 1H, CH_Py), 8.71 (d, ³J_HH= 4.9 Hz,

1H, NCH). ¹H NMR (CDCl₃, 213 K): 1.13 (dd, ³J_HH= 6.7 Hz,

³J_HH= 6.6 Hz, ³J_HP= 14.1 Hz, 6H, CHCH₃), 1.51 (dd, ³J_HH

=

3

7.4 Hz, J_HP= 15.9 Hz, 6H, CHCH₃), 1.84-1.91 (m, 2H,

CHH⁰_cisCP), 1.96-1.98 (m, 2H, CHH⁰_transCP), 2.23-2.32 (br s,

4H, CHH⁰), 2.70-2.78 (m, 2H, CHCH₃), 3.32 (s, 2H,

CH_COD;cisCP), 5.35 (s, 2H, CH_COD;transCP),), 7.59 (d, J_HH=

3

³J_HP= 13.2 Hz, 6H, CHCH₃), 1.33 (dd, ³J_HH= 7.4 Hz, ³J_HP

=

3

7.3 Hz, 1H, CH_Py), 7.76 (d, J_HH= 8.6 Hz, 1H, CH_Py), 7.81-

15.9 Hz, 3H, CHCH₃), 1.51 (br d, J = 8.6 Hz, 2H, CHH⁰_cisCP),

1.69 (br d, J = 8.6 Hz, 2H, CHH⁰_transCP), 2.14 (br d, J = 6.1 Hz,

4H, CH₂), 2.87-3.01 (hept, ³J_HH= 7.4 Hz, 2H, CHCH₃), 3.01

(s, 2H, CH_COD;cisCP), 4.84 (s, 2H, CH_COD;transCP), 7.28 (d,

³J_HH= 4.9 Hz, 1H, CH_Py), 7.58-7.62 (m, 1H, CH_Py),

7.68-7.72 (m, 1H, CH_Py), 8.70 (d, ³J_HH= 3.7 Hz, 1H, NCH).

¹³C{¹H} NMR (CDCl₃, 298 K): 18.9 (br s, CHCH₃), 19.3 (d,

7.85 (m, 2H, CH_Py). ¹³C{¹H} NMR (CDCl₃, 293 K): 19.1 (br s,

2

1

CHCH₃), 19.7 (d, J_CP= 4.4 Hz, CHCH₃), 24.3 (d, J_CP

22.0 Hz, CHCH₃), 28.6 (s, CH₂), 32.9 (s, CH₂), 69.2 (d, ¹J_RhC

=

13.9 Hz, CH_COD;cisCP), 103.5 (dd, ¹J_RhC= 11.7 Hz, ²J_CP= 7.3

Hz, CH_COD;transCP), 119.9 (s, CH_Py), 128.6 (s, CH_Py), 131.2 (d,

³J_CP= 15.3 Hz, CCF₃), 136.1 (d, ²J_CP= 5.9 Hz, PCCH_Py), 147.7

(dq, ¹J_CF= 35.1 Hz, J = 11.7 Hz, CF₃), 157.2 (d, ¹J_CP= 40.3

Hz, CP_Py). ³¹P{¹H} NMR (CDCl₃, 293K): 46.1 (d, ¹J_PRh= 144.7

Hz). ¹⁹F{¹H} NMR (CDCl₃, 293 K): -69.4 (s). Anal. Calcd

for C₂₀H₂₉NClF₃PRh: C 47.12, H 5.73, N 2.75. Found: C

47.04, H 5.59, N 2.97. FAB-MS m/z: 508.9 (M^þ, 11%), 473.9

(M^þ- Cl, 100%).

1

²J_CP= 2.8 Hz, CHCH₃), 23.7 (d, J_CP= 28.5 Hz, CHCH₃),

123.8 (s, CH_Py), 129.8 (d, ²J_CP= 18.4 Hz, PCCH_Py), 134.4 (d,

³J_CP₁= 7.4 Hz, CH_Py), 149.5 (d, ³J_CP= 12.0 Hz, NCH), 153.3

(d, J_CP= 55.2 Hz, CP_Py). ¹³C{¹H} NMR (CDCl₃, 213 K):

1

19.0 (s, CHCH₃), 19.4 (s, CHCH₃), 23.6 (d, J_CP= 22.7 Hz,

CHCH₃), 28.4 (s, CH₂), 32.7 (s, CH₂), 69.5 (s, CH_COD;cisCP),

Article

Organometallics, Vol. 28, No. 22, 2009 6399

102.8 (d, ²J_CP= 7.7 Hz, CH_COD;transCP), 123.8 (s, CH_Py), 129.8

(d, ²J_CP= 18.4 Hz, PCCH_Py), 134.4 (d, ³J_CP= 7.4 Hz, CH_Py),

149.5 (d, J_CP= 12.0 Hz, NCH), 153.3 (d, J_CP= 55.2 Hz,

CP_Py). ³¹P{¹H} NMR (CDCl₃, 298 K): 32.1 (s). Anal. Calcd for

C₁₉H₃₀NClPIr: C 42.97, H 5.67, N 2.64, Cl 6.69, P 5.69. Found:

C 42.18, H 5.94, N 2.48, Cl 7.10, P 5.69. FAB-MS (m/z): 531.1

(M^þ, 12%), 496.0 (M^þ- Cl, 100%), 531.1 (M^þ, 12%).

(CD₂Cl₂, 183 K): 1.26 (s, 2H, CH₂), 3.06 (br s, CH_nbd;cisCP), 3.67

(s, 2H, CH_allyl), 5.21 (s, 4H, CH_nbd;transCP), 7.23 (br s, 1H, CH_Py),

7.33-7.39 (m, 6H, CH_Ph), 7.61-7.70 (m, 6H, CH_Py, CH_Ph), 8.62

3

1

3

(d, J_HH= 3.7 Hz, NCH_Py). ¹³C{¹H} NMR (CDCl₃, 298 K):

50.6 (s, CH₂), 63.7 (d, J = 5.2 Hz, CH_allyl), 68.5 (br s, CH_nbd),

123.6 (s, CH_Py), 128.2 (d, J_CP= 10.4 Hz, CH_Ph), 130.2 (s,

3

1

CH_Ph), 131.2 (d, J_CP= 43.1 Hz, CP_Ph), 134.0 (br s, CH_Py),

2

Chlorocycloocta-1,5-diene(diphenyl-2-pyridylphosphine)-

rhodium(I) (2). Yellow powder (88%). This can be crystallized

overnight from a saturated acetone solution (orange crystals).

134.7 (br s, PCCH_Ph), 134.8 (d, J_CP= 10.4 Hz, PCCH_arom),

135.6 (br s, CH_Py), 150.0 (m, NCH_Py), 157.0 (d, ¹J_CP= 60.3 Hz,

CP_Py). ¹³C{¹H} NMR (CD₂Cl₂, 178 K): 50.5 (s, CH₂), 51.8 (br s,

CH_COD;cisCP), 63.6 (CH_allyl), 86.1 (br s, CH_COD;transCP), 123.7 (s,

CH_Py), 128.0 (d, ³J_CP= 10.2 Hz, CH_Ph), 130.2 (s, CH_Ph), 130.5

(d, ¹J_CP= 43.2 Hz, CP_Ph), 130.8 (d, ²J_CP= 24.2 Hz, PCCH_Py),

3

¹H NMR (CDCl₃, 298 K): 2.00 (br d, J_HH= 8.6 Hz, 4H,

CHH⁰), 2.39 (br s, 4H, CHH⁰), 4.46 (br s, 4H, CH_COD), 7.25 (d,

³J_HH= 4.9 Hz, 1H, CH_Py), 7.38-7.42 (m, 6H, CH_Ph), 7.66 (dt,

³J_HH= 7.4 Hz, ³J_HH= 4.9 Hz, 1H, NCHCH_Py), 7.83-7.92 (m,

5H, CH_PhþPy), 8.71 (d, ³J_HH= 4.9 Hz, 1H, NCH_Py). ¹H NMR

(CDCl₃, 213 K): 1.98 (br s, 2H, CH₂), 2.36 (s, 4H, CH₂), 3.32 (br

s, 2H, CH_COD;cisCP), 5.54 (br s, 2H, CH_COD;transCP), 7.27 (m, 1H,

CH_Py), 7.37-7.45 (m, 6H, CH_Ph), 7.67 (t, ³J_HH= 6.8 Hz, 1H,

NCHCH_Py), 7.80-7.88 (m, 5H, CH_PhþPy), 8.70 (d, ³J_HH= 3.7

Hz, 1H, NCH_Py). ¹³C{¹H} NMR (CDCl₃, 298 K): 30.9 (br s,

CH₂), 123.6 (s, CH_Py), 128.1 (d, ³J_CP= 10.3 Hz, CH_Ph), 130.3

(d, ⁴J_CP= 2.2 Hz, CH_Ph), 131.4 (d, ¹J_CP= 43.9 Hz, CP_Ph), 131.7

2

3

134.5 (d, J_CP= 12.5 Hz, PCCH_Ph), 135.7 (d, J_CP= 8.1 Hz,

CH_Py), 149.8 (m, NCH_Py), 155.8 (d, J_CP= 60.7 Hz, CP_Py).

1

³¹P{¹H} NMR (CDCl₃, 298 K): 29.5 (d, J_PRh= 169.3 Hz).

1

FAB-MS (m/z): 457.6 (M - Cl, 38%), 400.6 (M - nbd, 7%).

N-Methylchlorocycloocta-1,5-diene(diisopropyl-2-imidazyl-

phosphine)rhodium(I) (3-Me). Yellow powder (90%). ¹H NMR

(CDCl₃, 298 K): 1.16 (dd, ³J_HH= 7.4 Hz, ³J_HP= 15.9 Hz, 6H,

3

CHCH₃), 1.24 (dd, J_HH= 6.7 Hz, J_HP= 13.9 Hz, 6H,

CHCH₃), 2.05 (d, ³J_HH= 8.5 Hz, 4H, CHH⁰), 2.35 - 2.49 (m,

6H, CHCH₃, CHH⁰), 3.67 (br s, 2H, CH_COD;cisCP), 4.26 (s, 3H,

NCH₃), 5.44 (br s, 2H, CH_COD;transCP), 7.02 (s, 1H, CH_arom),

7.15 (s, 1H, CH_arom). ¹H NMR (CD₂Cl₂, 173 K): 0.77 (dd,

2

(d, J_CP= 24.9 Hz, PCCH_Py), 135.3 (d, J_CP= 11.7 Hz,

3

PCCH_Ph), 135.4 (d, J_CP= 11.0 Hz, CH_Py), 149.7 (d, J_CP

=

13.2 Hz, NCH_Py), 157.4 (d, J_CP= 60.8 Hz, CP_Py). ¹³C{¹H}

NMR (CDCl₃, 213 K): 28.6 (br s, CH₂), 32.8 (br s, CH₂), 70.5

(br s, CH_COD;cisCP), 105.4 (br s, CH_COD;transCP), 123.7 (s, CH_Py),

1

³J_HH= 6.1 Hz, ³J_HP= 15.9 Hz, 3H, CHCH₃), 0.90 (dd, ³J_HH

=

6.1 Hz, ³J_HP= 9.8 Hz, 3H, CHCH₃), 1.19 (dd, ³J_HH= 6.1 Hz,

=

3

4

128.0 (d, J_CP= 10.3 Hz, CH_Ph), 130.3 (d, J_CP= 5.9 Hz,

³J_HP= 15.9 Hz, 3H, CHCH₃), 1.31 (dd, ³J_HH= 6.1 Hz, ³J_HP

CH_Ph), 131.5 (d, ¹J_CP= 39.5 Hz, CP_Ph), 134.9 (d, ²J_CP= 11.7

Hz, CH_Ph), 135.5 (d, J_CP= 8.8 Hz, CH_Py), 149.7 (d, J_CP=

17.2 Hz, 3H, CHCH₃), 1.65 (m, 1H, CHCH₃), 1.89-1.94 (m,

2H, CH₂), 2.10-2.20 (m, 3H, CH₂), 2.31-2.48 (m, 3H, CH₂),

2.83-2.87 (m, 1H, CHCH₃), 3.62 (br s, 1H, CH_COD), 3.77 (br s,

1H, CH_COD), 4.18 (s, 3H, NCH₃), 5.20 (br s, 1H, CH_COD), 5.35

(br s, 1H, CH_COD), 7.08 (s, 1H, CH_arom), 7.10 (s, 1H, CH_arom).

¹³C{¹H} NMR (CDCl₃, 298 K): 18.8 (s, CHCH₃), 19.7 (d,

3

13.9 Hz, CH_Py), 156.5 (d, ¹J_CP= 61.5 Hz, CP_Py). ³¹P{¹H} NMR

(CDCl₃, 298 K): 28.5 (d, J_PRh= 150.6 Hz). Anal. Calcd for

1

C₂₅H₂₆NClPRh: C 58.90, H 5.14, N 2.75. Found: C 58.54, H

5.17, N 2.62. FAB-MS (m/z): 509.1 (M^þ, 509.1, 12%), 474.1

(M^þ- Cl, 100%), 401.0 (M^þ- COD, 26%), 365.1 (M^þ

COD - Cl, 4%).

Chloronorborna-2,5-diene(diisopropyl-2-pyridylphosphine)-

-

²J_CP= 4.4 Hz, CHCH₃), 24.2 (d, J_CP= 24.2 Hz, CHCH₃),

1

28.5 (s, CH₂), 33.2 (s, CH₂), 37.2 (d, J = 2.9 Hz, NCH₃), 69.7 (br

s, CH_cisCP), 104.6 (br s, CH_transCP), 104.6 (s, CH_arom), 129.6 (d, J

= 8.1 Hz, CH_arom), 139.1 (d, ¹J_CP= 59.3 Hz, CP_arom). ¹³C{¹H}

1

rhodium(I) (nbd-1). Yellow powder (85%). H NMR (CDCl₃,

298 K): 1.14 (dd, ³J_HH= 6.8 Hz, ³J_HP= 14.1 Hz, 6H, CHCH₃),

1.30 (dd, ³J_HH= 6.8 Hz, ³J_HP= 15.3 Hz, 6H, CHCH₃), 1.36 (s,

2H, CH₂), 2.48-2.58 (m, 2H, CHCH₃), 3.74 (s, 2H, CH_allyl),

4.31 (br s, 4H, CH_nbd), 7.21 (m, ³J_HH= 4.9 Hz, J = 2.4 Hz, 1H,

CH_Py), 7.61-7.67 (m, 2H, CH_Py), 8.66 (d, ³J_HH= 3.7 Hz, 1H,

NCH). ¹H NMR (CDCl₃, 213 K): 1.07 (dd, ³J_HH= 6.9 Hz, ³J_HP

= 13.8 Hz, 6H, CHCH₃), 1.22 (dd, ³J_HH= 6.9 Hz, ³J_HP= 16.1

Hz, 6H, CHCH₃), 1.35 (s, 2H, CH₂), 2.39-2.44 (m, 2H,

CHCH₃), 3.52 (br s, 2H, CH_nbd;cisCP), 3.77 (s, 2H, CH_allyl),

5.10 (br s, 4H, CH_nbd;transCP), 7.26 (m, 1H, CH_Py), 7.60 (m, 2H,

NMR (CD₂Cl₂, 173 K): 15.6 (s, CHCH₃), 15.6 (d, J_CP= 7.4

Hz, CHCH₃), 19.5 (s, CHCH₃), 20.6 (d, J_CP= 24.7 Hz,

2

1

CHCH₃), 25.2 (d, J_CP= 27.1 Hz, CHCH₃), 27.4 (s, CH₂),

28.9 (s, CH₂), 31.9 (s, CH₂), 33.6 (s, CH₂), 37.3 (s, NCH₃), 69.3

1

(d, ¹J_CRh= 14.8 Hz, CH_COD;cisCP), 69.7 (d, J_CRh= 12.3 Hz,

CH_COD;cisCP), 104.3-104.5 (m, CH_COD;transCP), 124.1 (s,

CH_arom), 128.8 (d, J = 7.4 Hz, CH_arom), 138.8 (d, ¹J_CP= 61.7

=

Hz, CP_arom). ³¹P{¹H} NMR (CDCl₃, 298 K): 21.4 (d, ¹J_PRh

142.7 Hz). Anal. Calcd for C₁₈H₃₁N₂ClPRh: C 48.61, H 7.03, N

6.30, Cl 7.97, P 6.96. Found: C 48.12, H 7.14, N 5.60, Cl 8.49, P

6.79. FAB-MS (m/z): 444.1 (M^þ, 2%), 409.1 (M^þ- Cl, 100%),

336.0 (M^þ- COD, 30%) 301.0 (M^þ- COD - Cl, 8%).

N-Isopropylchlorocycloocta-1,5-diene(diisopropyl-2-imidazyl-

phosphine)rhodium(I) (3-ⁱPr). Yellow powder (89%). ¹H NMR

(CDCl₃, 298 K): 1.19 (dd, ³J_HH= 7.4 Hz, ³J_HP= 14.7 Hz, 6H,

3

CH_Py), 8.66 (d, J_HH= 4.6 Hz, 1H, NCH). ¹³C{¹H} NMR

2

(CDCl₃, 298 K): 18.7 (s, CHCH₃), 19.1 (s, J_CP= 4.4 Hz,

CHCH₃), 23.1 (d, ¹J_CP= 22.0 Hz, CHCH₃), 50.7 (s, CH₂), 63.8

(d, J = 4.4 Hz, CH_allyl), 123.5 (s, CH_Py), 130.4 (d, ²J_CP= 21.2

3

Hz, CH_Py), 134.7 (d, J_CP= 8.1 Hz, CH_Py), 149.6 (d, J_CP

=

11.0 Hz, CH_Py), 154.1 (d, ¹J_CP= 46.8 Hz, CP_Py). ¹³C{¹H} NMR

(CDCl₃, 213 K): 18.3 (s, CHCH₃), 18.8 (d, ²J_CP= 4.9 Hz, CH-

CH₃), 22.3 (d, ¹J_CP= 22.2 Hz, CHCH₃), 50.6 (br s, CH_nbd;cisCP),

50.8 (s, CH₂), 63.9 (d, J = 4.9 Hz, CH_allyl), 83.7 (br s,

CH_nbd;transCP), 123.8 (s, CH_Py), 130.9 (d, ²J_CP= 22.2 Hz, CH_Py),

PCHCH₃), 1.33 (dd, J_HH= 7.4 Hz, J_HP= 14.7 Hz, 6H,

3

PCHCH₃), 1.56 (d, J_HH= 6.1 Hz, 6H, NCHCH₃), 2.02 (d,

³J_HH= 8.6 Hz, 4H, CHH⁰), 2.34 (br s, 4H, CHH⁰), 2.53-2.59

(m, 2H, PCHCH₃), 6.25-6.32 (m, 1H, NCHCH₃), 7.13 (s, 1H,

CH_arom), 7.17 (s, 1H, CH_arom). ¹³C{¹H} NMR (CDCl₃, 298 K):

19.5 (s, PCHCH₃), 20.4 (s, PCHCH₃), 24.6 (s, NCHCH₃), 25.1

3

134.8 (d, J_CP= 7.4 Hz, CH_Py), 149.5 (d, J_CP= 12.0 Hz,

NCH_Py), 152.8 (d, J_CP= 46.9 Hz, CP_Py). ³¹P{¹H} NMR

(CDCl₃, 298 K): 44.5 (d, J_PRh= 166.5 Hz). Anal. Calcd for

(d, J_CP= 23.4 Hz, PCHCH₃), 28.9 (vbr s, CH₂), 33.2 (vbr s,

CH₂), 37.2 (d, J = 2.9 Hz, NCH₃), 49.7 (d, J_CP= 4.4 Hz,

NCHCH₃), 69.5 (vbr s, CH_COD;cisCP), 103.9 (vbr s, CH_COD;

1

3

C₁₈H₂₆NClPRh: C 50.78, H 6.16, N 3.29, Cl 8.33, P 7.28. Found:

C 49.93, H 6.04, N 3.22, Cl 8.41, P 6.78. FAB-MS (m/z): 425.1

(M, 12%), 390.2 (M^þ- Cl, 100%), 333.1 (M^þ- nbd, 37%).

Chloronorborna-2,5-diene(diphenyl-2-pyridylphosphine)-

3

_transCP), 118.7 (s, CH_arom), 130.4 (d, J_CP= 8.8 Hz, CH_arom),

139.5 (d, ¹J_CP= 59.3 Hz, CP_arom). ³¹P{¹H} NMR (CDCl₃, 298

K): 17.7 (d, ¹J_PRh= 142.6 Hz). Anal. Calcd C₂₀H₃₅N₂ClPRh: C

50.80, H 7.46, N, 5.92. Found: C 50.27, H 7.40, N 5.64. FAB-MS

(m/z): 436.6 (M^þ- Cl, 100%).

1

rhodium(I) (nbd-2). Yellow powder (85%). H NMR (CDCl₃,

298 K): 1.36 (s, 2H, CH₂), 3.71 (s, 2H, CH_allyl), 4.24 (s, 4H,

CH_nbd), 7.25 (m, 1H, CH_Py), 7.36-7.41 (m, 6H, CH_Ph), 7.63 (t,

³J_HH= 7.4 Hz, CH_Py), 7.74 (t, ³J_HH= 9.2 Hz, CH_Ph), 7.82 (t,

³J_HH= 7.7 Hz, CH_Py), 8.69 (d, ³J_HH= 4.9 Hz, CH_Py). ¹H NMR

N-Methylchlorocycloocta-1,5-diene(diisopropyl-2-benzimidazyl-

phosphine)rhodium(I) (4). Must be washed with cold n-pentane

in the workup. Yellow powder (84%). ¹H NMR (CDCl₃,

6400 Organometallics, Vol. 28, No. 22, 2009

Bru€ck and Ruhland

298 K): 1.23 (dd, ³J_HH= 7.4 Hz, ³J_HP= 15.9 Hz, 6H, CHCH₃),

1.32 (dd, ³J_HH= 6.8 Hz, ³J_HP= 14.1 Hz, 6H, CHCH₃), 2.07 (br

d, ³J_HH= 8.6 Hz, 4H, CH₂), 2.43 (br s, 4H, CH₂), 2.61-2.68 (m,

2H, CHCH₃), 3.74 (br s, 2H, CH_COD;cisCP), 4.41 (s, 3H, NCH₃),

5.50 (br s, 2H, CH_COD;transCP), 7.24-7.31 (m, 2H, CH_arom), 7.37

(d, ³J_HH= 7.4 Hz, 1H, CH_arom), 7.79 (d, ³J_HH= 8.6 Hz, 1H,

CH_arom). ¹³C{¹H} NMR (CDCl₃, 298 K): 19.1 (s, CHCH₃), 19.8

flask, suspended in 5 mL of dichloromethane, and stirred for

1.5 h at room temperature. Then 2 mg (0.13 mmol) of solid

sodium iodide was added, and the reaction mixture stirred

overnight. After filtration and removal of the solvent in vacuo,

the crude product was washed 3ꢀ with n-pentane and dried in

vacuo to yield a yellow powder (63%). ¹H NMR (CDCl₃, 293 K):

1.21 (dd, ³J_HH= 7.4 Hz, ³J_HH= 7.4 Hz, 6H, CHCH₃), 1.56 (dd,

³J_HH= 7.4 Hz, ³J_HH= 7.4 Hz, 6H, CHCH₃), 1.75 (br s, 4H,

CHH⁰), 2.17 (br d, J = 7.4 Hz, 4H, CHH⁰), 2.78-2.91 (m, 2H,

CHCH₃), 7.21 (t, ³J_HH= 6.1 Hz, 1H, CH_Py), 7.46 (d, ³J_HH= 7.4

Hz, 1H, CH_Py), 7.61-7.66 (m, 1H, CH_Py), 8.67 (d, ³J_HH= 3.7

1

(s, CHCH₃), 24.4 (d, J_CP= 24.2 Hz, CHCH₃), 28.6 (br s,

CH_2allyl), 33.3 (br s, CH_2allyl), 34.7 (s, NCH₃), 70.0 (br s,

CH_COD;cisCP), 105.1 (br s, CH_COD;transCP), 109.9 (s, CH_arom),

120.1 (dd, J = 9.9 Hz, J = 4.9 Hz, CH_arom), 122.3 (s, CH_arom),

123.3 (s, CH_arom), 137.1 (s, NC), 143.2 (s, NC), 147.1 (d,

¹J_CP= 51.8 Hz, CP_arom). ³¹P{¹H} NMR (CDCl₃, 298 K): 23.6

(d, ¹J_PRh= 142.6 Hz). FAB-MS (m/z): 485.5 (M - Cl, 100%),

385.5 (M^þ- COD). Anal. Calcd for C₂₂H₃₃N₂ClPRh: C 53.40,

H 6.72, N 5.66, Cl 7.16, P 6.26. Found: C 53.79, H 6.93, 5.40,

Cl 6.91, P 6.10.

Hz, 1H, NCH_Py). ¹H NMR (CDCl₃, 213 K): 1.17 (dd, ³J_HH

=

6.7 Hz, ³J_HH= 12.2 Hz, 6H, CHCH₃), 1.51 (dd, ³J_HH= 6.7 Hz,

³J_HH= 14.3 Hz, 6H, CHCH₃), 1.57-1.61 (m, 2H, CHH⁰_cisCP),

1.87-1.91 (m, 2H, CHH⁰_transCP), 2.10-2.19 (m, 4H, CHH⁰),

2.74-2.80 (m, 2H, CHCH₃), 7.56 (d, ³J_HH= 6.1 Hz, 1H, CH_Py),

7.46 (d, ³J_HH= 7.4 Hz, 1H, CH_Py), 7.66-7.70 (m, 1H, CH_Py),

8.67 (d, ³J_HH= 4.9 Hz, 1H, NCH_Py). ¹³C{¹H} NMR (CDCl₃,

Chloro-2,6-cyclooctadienone(diisopropyl-2-pyridylphosphine)-

rhodium(I). Yellow powder (95%). This can be crystallized from

a saturated acetone solution (orange-red crystals). ¹H NMR

1

293 K): 19.5 (s, CH₃), 20.5 (s, CH₃), 26.5 (d, J_CP= 23.4 Hz,

CHCH₃), 30.9 (vbr s, CH₂), 123.3 (s, CH_Py), 128.1 (d, J_CP=

2

3

(CDCl₃, 298 K): 1.05 (dd, J_HH= 6.8 Hz, J_HP= 14.1 Hz,

CHCH₃), 1.25 (dd, ³J_HH= 6.8 Hz, ³J_HP= 15.3 Hz, CHCH₃),

13.9 Hz, PCCH_Py), 134.5 (d, ³J_CP= 5.9 Hz, CH_Py), 149.4 (d, J

1

= 12.4 Hz, NCH_Py), 156.4 (d, J_CP= 44.6 Hz, CP). ¹³C{¹H}

3

1.44 (d d, J_HH= 7.4 Hz, J_HP= 9.8 Hz, CHCH₃), 1.50 (dd,

³J_HH= 7.9 Hz, ³J_HP= 16.5 Hz, CHCH₃), 1.59-1.63 (m, 1H,

CH₂), 1.87-1.94 (m, 1H, CH₂), 2.28-2.31 (m, 1H, CH₂),

2.47-2.52 (m, 1H, CH₂), 2.63-2.68 (m, 1H, CHCH₃),

NMR (CDCl₃, 213 K): 19.4 (s, CH₃), 20.5 (s, CH₃), 25.9 (d, ¹J_CP

= 22.7 Hz, CHCH₃), 29.3 (s, CH₂), 32.1 (s, CH₂), 72.8 (d, ¹J_CRh

= 12.4 Hz, CH_COD;cisCP), 100.3 (dd, J_CP= 6.6 Hz, J_CRh=

2

1

12.4 Hz, CH_COD;transCP), 123.4 (s, CH_Py), 128.0 (d, ²J_CP= 13.9

3

2.71-2.80 (m, 2H, CHCH₃, COCHH⁰), 2.87-2.93 (dd, J_HH

Hz, PCCH_Py), 134.7 (d, ³J_CP= 5.9 Hz, CH_Py), 149.4 (d, ³J_CP

=

2

= 7.3 Hz, J_HH= 17.1 Hz, 1H, COCHH⁰), 3.03 (br s, 1H,

CH_COD), 3.90 (br s, 1H, CH_COD), 4.99 (br s, 1H, CH_COD), 5.55

12.4 Hz, NCH_Py), 155.4 (d, ¹J_CP= 45.4 Hz, CP). ³¹P{¹H} NMR

(CDCl₃, 293 K): 47.5 (d, ¹J_PRh= 140.7 Hz). FAB-MS: 425.0 (M

- COD, 7.5%), 406.2 (M^þ- I, 100%).

(br s, 1H, CH_COD), 7.20 (s, 1H, CH_Py), 7.43 (d, ³J_HH= 7.4 Hz,

3

CH_Py), 7.61-7.63 (m, 1H, CH_Py), 8.64 (d, J_HH= 3.7 Hz,

Dideutero-1,5-cyclooctadiene. To a cold solution (ca. -100 °C;

2-propanol þ liquid N₂) of 4.3 mL of tert-butyllithium in

heptane (1.6 mol/L; 6.4 mmol) and 20 mL of tetrahydrofuran

(THF) was added 0.57 g (2.13 mmol) of dibromocyclooctadiene

in 5 mL of THF. The solution immediately turned dark, and the

mixture was stirred for another 5 min. Then 1.9 mL (10.6 mmol)

of deuterium oxide was added quickly, and the mixture was

allowed to warm slowly overnight, while a white precipitate

(LiOH) was formed. The solvent was removed in vacuo and the

product was extracted with diethyl ether (3ꢀ 10 mL). The

combined organic fractions were dried with magnesium sulfate

and filtered, and the solvent was removed in vacuo, yielding

0.08 g (34%) of product as a light yellow liquid. The product was

NCH). ¹³C{¹H} NMR (CDCl₃, 298 K): 18.6 (d, ²J_CP= 2.2 Hz,

CHCH₃), 18.6 (d, J_CP= 2.9 Hz, CHCH₃), 19.9 (s, CHCH₃),

2

1

18.6 (d, J_CP= 3.7 Hz, CHCH₃), 18.6 (d, J_CP= 8.8 Hz,

CHCH₃), 18.6 (d, ¹J_CP= 9.5 Hz, CHCH₃), 28.5 (s, CH₂), 31.6

(s, CH₂), 41.4 (s, COCH₂), 70.1 (br s, CH_COD), 70.9 (br s,

CH_COD), 84.2 (br s, CH_COD), 107.5 (br s, CH_COD), 123.8 (d,

⁴J_CP= 2.2 Hz, CH_Py), 128.1 (d, ²J_CP= 14.6 Hz, CH_Py), 135.2

(d, ³J_CP= 5.9 Hz, CH_Py), 149.8 (d, ³J_CP= 13.2 Hz, NCH_Py),

1

154.2 (d, J_CP= 51.2 Hz, CP_Py), 205.4 (d, J = 3.7 Hz, CO).

1

³¹P{¹H} NMR (CDCl₃, 298 K): 45.5 (d, J_P_þ_Rh= 145.5 Hz).

FAB MS (m/z): 520.3 [(O-CODRhCl)₂

,

25%], 492.3

[(Rh(NP)₂)^þ, 100%], 419.4 (M^þ- Cl, 81%), 332.5 (M^þ

-

1

COD, 37%). IR (KBr pellet): 3058 (m), 2960 (m), 2925 (m),

2867 (m), 1680 (vs, CO), 1571 (m), 1563 (m), 1449 (m), 1420 (m),

1381 (w), 1362 (w), 1334 (w), 1303 (w), 1262 (w), 1243 (m), 1184

(w), 1161 (w), 1132 (w), 1102 (w), 1089 (w), 1062 (w), 1032 (w),

987 (m), 696 (w), 930 (vw), 883 (w), 865 (vw), 809 (w), 772 (w),

748 (w), 720 (w), 657 (w), 633 (w), 617 (w), 526 (m).

used without further purification. H NMR (CDCl₃, 298 K):

2.35 (s, 8H), 5.57 (s, 2.5H; deuteration grade ca. 75%). ¹³C{¹H}

NMR (CDCl₃, 298 K): 27.9 (s, CH₂), 28.0 (s, CH₂), 128.2 (m,

CD), 128.5 (s, CH), 128.7 (s, CH). One data set for each isomer

2

(1,5-dideutero- þ 1,6-dideutero-1,5-cyclooctadiene). H NMR

(CDCl₃, 298 K): 5.6 (s).

Chloro-2,6-cyclooctadienonerhodium(I) Dimer. One equiva-

lent of chlorodicyclooctenerhodium(I) dimer was stirred with

3 equiv of 2,6-cylooctadienone in dichloromethane for 1 h.

Removal of the solvent in vacuo and washing of the crude

product twice with n-pentane yielded the product as a yellow

Chlorodideutero-1,5-cyclooctadiene(diisopropyl-2-pyridylphos-

phine)rhodium(I) (1-COD-d₂). One equivalent of chloro-

dicyclooctenerhodium(I) dimer was stirred with 3 equiv of

dideutero-1,5-cylooctadiene in dichloromethane for 1 h. After

removal of the solvent in vacuo, 2.1 equiv of the ligand was

added and the mixture stirred for another hour in dichloro-

methane. Removal of the solvent in vacuo, washing the crude

product twice with n-pentane, and crystallization from a satu-

rated acetone solution yielded the complex as yellow crystals

(50%). The deuteration grade is ca. 75% due to integrals of the

olefinic groups in ¹H NMR. ¹H NMR (CDCl₃, 293 K): 1.21 (dd,

1

powder (80%). H NMR (CDCl₃, 298 K): 1.48-1.53 (m, 1H,

CH₂), 1.86-1.91 (m, 1H, CH₂), 2.41-2.52 (m, 2H, CH₂),

2.72-2.99 (m, 1H, CH₂), 2.99-3.06 (m, 1H, CH₂), 4.05-4.08

(m, 2H, CH), 4.56-4.61 (m, 2H, CH). ¹³C{¹H} NMR (CDCl₃,

298 K): 29.3 (s, CH₂), 31.2 (s, CH₂), 41.4 (s, CH₂), 60.4 (d, ¹J_CP

= 13.2 Hz, CH), 77.9 (d, ¹J_CP= 14.6 Hz, CH), 79.3 (d, ¹J_CP

=

15.4 Hz, CH), 84.9 (d, ¹J_CP= 13.2 Hz, CH), 206.4 (s, CO). FAB-

MS (m/z): 520.1 (M, 5%, correct isotope pattern). FT-IR (KBr

pellet): 2996 (w), 2940 (m), 2886 (w), 2830 (w), 1688 (vs, CO),

1482 (w), 1467 (w), 1434 (w), 1418 (w), 1375 (w), 1351 (w), 1332

(w), 1300 (w), 1274 (w), 1240 (w), 1227 (w), 1183 (w), 1132 (w),

1063 (w), 1033 (w), 975 (m), 877 (w), 853 (w), 827 (w).

³J_HH= 6.7 Hz, ³J_HH= 14.1 Hz, 6H, CHCH₃), 1.51 (dd, ³J_HH

=

6.7 Hz, ³J_HH= 15.3 Hz, 6H, CHCH₃), 1.88 (d, ³J_HH= 7.4 Hz,

4H, CHH⁰), 2.28 (br d, ³J_HH= 8.6 Hz, 4H, CHH⁰), 2.68-2.78

(m, 2H, CHCH₃), 7.21 (d, ³J_HH= 6.1 Hz, 1H, CH_Py), 7.50 (d,

³J_HH= 7.4 Hz, 1H, CH_Py), 7.61-7.65 (m, 1H, CH_Py), 8.67 (d,

1

³J_HH= 4.9 Hz, 1H, NCH_Py). H NMR (CDCl₃, 213 K): 1.17

3

(dd, J_HH= 7.4 Hz, J_HH= 7.4 Hz, 6H, CHCH₃), 1.45 (dd,

3

1,5-Cyclooctadieneiodo(diisopropyl-2-pyridylphosphine)-

rhodium(I) (I-1). Silver tetrafluoroborate (9 mg, 0.05 mmol) was

added to 20 mg (0.045 mmol) of chloro-1,5-cyclooctadiene-

(diisopropyl-2-pyridylphosphine)rhodium(I) (1) in a Schlenk

³J_HH= 7.4 Hz, ³J_HH= 7.4 Hz, 6H, CHCH₃), 1.79 (d, ³J_HH

=

8.6 Hz, 2H, CHH⁰), 1.93 (d, ³J_HH= 8.6 Hz, 2H, CHH⁰), 2.30 (br

d, ³J_HH= 8.6 Hz, 4H, CHH⁰), 2.62-2.71 (m, 2H, CHCH₃), 3.34

Article

Organometallics, Vol. 28, No. 22, 2009 6401

1

32.3 (s, CH₂), 78.0 (d, J_CP= 11.7 Hz, CH_COD;cisCP), 98.9

(s, 1H, CH_COD), 5.25 (s, 1H, CH_COD), 7.26 (d, ³J_HH= 5.5 Hz,

1H, CH_Py), 7.51 (d, ³J_HH= 7.4 Hz, 1H, CH_Py), 7.65-7.70 (m,

1

2

(pseudo-t, J_CRh= 8.8 Hz, J_CP= 8.8 Hz, CH_COD;transCP),

127.9 (s, CH_Py), 131.0 (s, CH_Py), 140.5 (s, CH_Py), 148.6 (d, ²J_CP

= 11.7 Hz, NCH_Py), 155.5 (d, ¹J_CP= 40.3 Hz, J = 5.1 Hz, CP).

³¹P{¹H} NMR (CDCl₃, 293 K): -11.9 (d, ¹J_PRh= 120.9 Hz).

¹⁵N- 1,5-Cyclooctadiene[K²-N,P-diisopropyl-(3,5-dimethyl-

2-pyridylphosphine]rhodium(I) Tetrafluoroborate [1-Me₂-¹⁵N]BF₄.

Silver tetrafluoroborate (1.1 equiv) was added to a NMR sample

3

2

1H, CH_Py), 8.67 (d, J_HH= 3.7 Hz, 1H, NCH_Py). H NMR

(CDCl₃, 293 K): 4.36 (br s, CD_COD). ²H NMR (CDCl₃, 213 K):

3.38 (s, CD_COD;cisCP), 5.28 (s, CD_COD;transCP). ¹³C{¹H} NMR

(CDCl₃, 293 K): 19.2 (s, CHCH₃), 19.8 (s, CHCH₃), 24.1 (d, ¹J_CP

= 22.1 Hz, CHCH₃), 30.6 (vbr s, CH_allyl), 69.8 (vbr s, CH₂),

2

102.8 (vbr s, CH₂), 123.3 (s, CH_Py), 128.5 (d, J_CP= 16.6 Hz,

PCCH_Py), 134.6 (d, ³J_CP= 6.4 Hz, CH_Py), 149.5 (d, ³J_CP= 12.9

Hz, NCH_Py), 155.4 (d, ¹J_CP= 46.9 Hz, CP_Py). ¹³C{¹H} NMR

(CDCl₃, 213 K): 18.9 (s, CHCH₃), 19.3 (s, CHCH₃), 23.5 (d, ¹J_CP

= 22.1 Hz, CHCH₃), 28.4 (s, CH₂), 32.6 (s, CH₂), 69.4 (d, ¹J_CRh

= 12.9 Hz, CH_{CO2 D;cisCP}), 102.8 (m, CH_COD;transCP), 123.5 (s,

CH_Py), 128.5 (d, J_CP= 14.7 Hz, PCCH_Py), 134.8 (s, CH_Py),

of

¹⁵N-chloro-1,5-cyclooctadiene[diisopropyl(3,5-dimethyl-2-

pyridyl)phosphine]rhodium(I) in CDCl₃. The mixture was

heated for 1 h at 50 °C and directly filtered in a second NMR

tube. The compound was stable in solution for several days, but

isolation attempts resulted in complete decomposition. ¹H

3

NMR (CDCl₃, 293 K): 1.24 (d, J_HH= 7.4 Hz, 6H, CHCH₃),

3

1

149.5 (d, J_CP= 12.0 Hz, NCH_Py), 154.3 (d, J_CP= 45.4 Hz,

CP_Py). ³¹P{¹H} NMR (CDCl₃, 293 K): 40.4 (d, ¹J_PRh= 145.5

Hz). FAB-MS (m/z): 407.8 (M^þ- Cl, 100%, correct isotope

pattern).

1.28 (dd, ³J_HH= 7.4 Hz, ³J_PH= 2.5 Hz, 6H, CHCH₃), 2.08 (d,

³J_HH= 8.6 Hz, 4H, CH₂), 2.32 (br d, J = 2.5 Hz, 3H, CH_3;Py),

2.42-2.56 (m, 6H, CHCH₃, CH₂), 2.44 (s, 3H, CH_3;Py), 4.43 (s,

CH_COD), 5.64 (s, CH_COD), 7.22 (s, CH_Py), 7.33 (s, CH_Py).

¹³C{¹H} NMR (CDCl₃, 293 K): 18.6 (s, CHCH₃), 19.0

Chloro-1,5-cyclooctadien-(diisopropyl-2-pyridiniumylphosphane)-

2

rhodium(I) 4-Methylphenylsulfonate (1-H^þ). To a NMR solu-

tion of 1 was added 1 equiv of para-toluenesulfonic acid. H

(d, J_CP= 3.9 Hz, CHCH₃), 21.4 (s, CH_3;Py), 22.0 (s, CH_3;Py),

24.4 (d, ¹J_CP= 19.7 Hz, CHCH₃), 28.9 (s, CH₂), 32.0 (s, CH₂),

1

NMR (CDCl₃, 298 K): 1.20 (t, ³J_HH= 7.7 Hz, 12H, CHCH₃),

2.05 (d, ³J_HH= 9.2 Hz, 4H, CHH⁰), 2.36 (s, 3H, C_PhCH₃), 2.47

73.3 (d, ¹J_CP= 12.8 Hz, CH_COD;cisCP), 101.0 (pseudo-t, ¹J_CRh

=

7.9 Hz, ²J_CP= 7.9 Hz, CH_COD;transCP), 107.4 (d, J_CP= 7.9 Hz,

CH_Py), 128.8 (d, J = 31.5 Hz, CH_Py), 152.8 (t, J = 3.9 Hz, CH_Py),

3

(s, 4H, CHH⁰), 2.61 (h, J_HH= 6.7 Hz, CHCH₃), 3.79 (s, 2H,

CH_COD), 5.49 (s, 2H, CH_COD), 7.18 (d, J_HH= 8.0 Hz, 2H,

159.9 (d, J_CP= 11.7 Hz, J_CN= 12.3 Hz, CH_Py), 155.5 (d, ¹J_CP

=

3

CH_arom), 7.81 (d, ³J_HH= 8.0 Hz, 2H, CH_arom), 7.96 (t, ³J_HH

=

44.3 Hz, J_CN₁= 4.9 Hz, CP). ³¹P{¹H} NMR (CDCl₃, 293 K):

6.7 Hz, 1H, CH_Py), 8.31 (d, ³J_HH= 8.0 Hz, 1H, CH_arom), 8.39 (t,

³J_HH= 8.0 Hz, 1H, CH_Py), 9.46 (d, ³J_HH= 5.9 Hz, 1H, CH_Py).

³¹P{¹H} NMR (CDCl₃, 293 K): 48.7 (d, ¹J_PRh= 151.5 Hz).

cis-1,5-Cyclooctadiene(-K²-N,P-diisopropyl-2-pyridylphosphine)-

rhodium(I) Tetrafluoroborate (1-BF₄). Silver tetrafluoroborate

(1.1 equiv) was added to a NMR sample of 1 in CDCl₃. The

mixture was heated for 1 h at 50 °C and directly filtered in a

second NMR tube. The compound was stable in solution for

several days, but isolation attempts resulted in complete decom-

position. ¹H NMR (CDCl₃, 293 K): 1.23-1.26 (m, 6H,

-13.1 (dd, J_PRh= 121.8 Hz, J = 11.9 Hz). ¹⁵N{¹H} NMR

1

(CDCl₃, 293 K): -135.1 (pseudo-t, J_NRh= 11.9 Hz, J_NP

11.9 Hz).

=

Acknowledgment. K.R. thanks Prof. W. A. Herrmann

for the opportunity to use the infrastructure of his chair.

K.R. and A.B. thank NANOCAT (an International

Graduate Program within the Elitenetzwerk Bayern) for

financial support. Dr. Eberhardt Herdtweck, Dr. Ste-

phan Hoffmann, Dr. Florian Kraus, Dr. Bernhard Wahl,

and Sandra Scharfe are acknowledged for their support

with the X-ray analysis.

3

CHCH₃), 1.30 (dd, J_HH= 7.4 Hz, J_HP= 2.5 Hz, 6H,

CHCH₃), 2.11-2.22 (m, 4H, CH₂), 2.41-2.58 (m, 6H, CHCH₃,

CH₂), 4.64 (s, 2H, CH_COD), 5.35 (s, 2H, CH_COD), 7.69-7.74 (m,

2H, CH_Py), 8.10-8.16 (m, 2H, CH_Py). ¹³C{¹H} NMR (CDCl₃,

293 K): 19.1 (s, CHCH₃), 19.3 (d, ²J_CP= 6.6 Hz, CHCH₃), 22.8

Supporting Information Available: This material is available

free of charge via the Internet at http://pubs.acs.org.

2

(d, J_CP= 6.6 Hz, CHCH₃), 28.5 (s, CH_2;allyl), 29.7 (s, CH₂),

Article Doi

Investigation of the dynamic solution behavior of chloro(diene)rhodium(I) phosphine complexes with a pendant unsaturated heterocycle at phosphorus (2-pyridyl, 2-imidazyl; diene = COD, NBD)

DOI: 10.1021/om900324a

Source and publish data:

Authors:

Article abstract of DOI:10.1021/om900324a

Full text of DOI:10.1021/om900324a

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