Reactivity of dimeric cyclopalladated complexes with an (sp3)C-Pd bond toward KPPh2

Article abstract of DOI:10.1016/j.jorganchem.2015.07.023

Abstract Reactions of KPPh₂ with dimeric C,N, C,P and C,S cyclopalladated complexes (CPCs) 1a-g containing an (sp³)C-Pd bond were investigated. The CPCs used in the study were obtained from D-camphor O-methyloxime (a), l-fenchone O-methyloxime (b), 4,4-dimethyl-2-phenyl-2-oxazoline (c), 8-methylquinoline (d), trimesitylphosphine (e), tri(O-tolyl)phosphine (f) and 2,6-dimethylthioanisole (g). The dichloro-bridged CPCs 1a,b,d,f,g and the diacetato-bridged analog μ-OAc-1d reacted with 4.5 equiv. of KPPh₂ at room temperature in THF to give either phosphines 2a,b or phosphine oxides 8d,f,g in 20-51% yield. Complexes 1a,b,d reacted with 1 equiv. of KPPh₂ to produce the corresponding μ-chloro-μ-diphenylphosphido-CPCs 3a,b,d in 33-56% yield. In the reaction of CPC 1c with 4.5 equiv. of KPPh₂, complex 4c with two PPh₂ bridging ligands was isolated in 36% yield. Structures of phosphines 2a,b, phosphine oxides 8a,d,f,g as well as complexes 3a,b,d and 4c were confirmed by ¹H, ¹³C{¹H} and ³¹P{¹H} NMR spectroscopy.

Full text of DOI:10.1016/j.jorganchem.2015.07.023

Journal of Organometallic Chemistry 797 (2015) 13e20
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Communication
Reactivity of dimeric cyclopalladated complexes with an (sp3)CePd
bond toward KPPh2
Gerard C. Dickmu, Nicholas J. Korte, Irina P. Smoliakova*
Department of Chemistry, University of North Dakota, 151 Cornell Street, Mail Stop 9024, Grand Forks, ND 58202-9024, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
Reactions of KPPh2 with dimeric C,N, C,P and C,S cyclopalladated complexes (CPCs) 1aꢀg containing an
(sp3)CePd bond were investigated. The CPCs used in the study were obtained from D-camphor O-
Received 17 June 2015
Received in revised form
17 July 2015
Accepted 18 July 2015
Available online 26 July 2015
methyloxime (a),
methylquinoline (d), trimesitylphosphine (e), tri(O-tolyl)phosphine (f) and 2,6-dimethylthioanisole (g).
The dichloro-bridged CPCs 1a,b,d,f,g and the diacetato-bridged analog -OAc-1d reacted with 4.5 equiv.
of KPPh2 at room temperature in THF to give either phosphines 2a,b or phosphine oxides 8d,f,g in 20
e51% yield. Complexes 1a,b,d reacted with 1 equiv. of KPPh2 to produce the corresponding -chloro-m-
L-fenchone O-methyloxime (b), 4,4-dimethyl-2-phenyl-2-oxazoline (c), 8-
m
m
Keywords:
diphenylphosphido-CPCs 3a,b,d in 33e56% yield. In the reaction of CPC 1c with 4.5 equiv. of KPPh2,
complex 4c with two PPh2 bridging ligands was isolated in 36% yield. Structures of phosphines 2a,b,
phosphine oxides 8a,d,f,g as well as complexes 3a,b,d and 4c were confirmed by 1H, 13C{1H} and 31P{1H}
NMR spectroscopy.
Cyclopalladated complex
N,P, S,P, P,P ligands
(sp3)CePd bond
Phosphination
KPPh2
© 2015 Elsevier B.V. All rights reserved.
1. Introduction
report our data on reactivity of C,N, C,P and C,S palladacycles with
an (sp3)CePd bond toward KPPh2.
Reactions involving a CePd bond in cyclopalladated complexes
(CPCs) represent a valuable approach for the synthesis of com-
pounds that are not readily available by other methods [1]. Also,
studies of these reactions shed light on mechanisms of palladium-
catalyzed transformations [2]. Despite the abundance of reported
reactions at the (sp2)CePd bond of palladacycles [1], there are only
a limited number of aliphatic CPCs and reagents studied in this type
of transformation. The reagents that have been used in reactions of
CPCs at the (sp3)CePd bond include electron-deficient alkynes [3],
benzyl isocyanide [4], CO with or without MeOH [4,5], I2 [6,7], Cl2
[8], Et3BnNCl [7], methyl vinyl ketone [5], and alkyl iodides [5].
Several research groups reported oxidation of C,N CPCs obtained
from oximes with bulky alkyl substituents [9]. The formation of an
(sp3)Ce(sp2)C bond was observed in the reaction of Me3SnPh with a
C,P palladacycle having a benzylic CePd bond [10].
2. Results and discussion
2.1. KPPh2 reactions of CPCs with an (sp3)CePd bond
Previously, we showed that both LiPPh2 and KPPh2 are capable
of reacting with dimeric chloro-bridged CPCs [11,12]. However, the
outcome of the LiPPh2 reactions with CPCs was highly sensitive to
the phosphide structure in the solution, which in turn, depended
on the preparation method, concentration and age of the chemical.
KPPh2 in a solution appears to exist only in a monomeric form, and
reactivity of the commercial reagent and the one prepared in our
lab from ClPPh2 and K in THF was proven to be the same. In the
present investigation, we used only commercially available KPPh2
as a phosphide source.
The dimeric dichloro-bridged C,N CPC 1a derived from OeMe
camphor oxime [15] was chosen as a model complex for our study.
Complex 1a reacted with 4.5 equiv. of KPPh2 in THF at rt for 18 h to
give the desired N,P ligand 2a in 21% yield (Scheme 2). Increasing
the reaction temperature to 40 ꢁC resulted in 5% yield of 2a.
Considering that the bidentate ligand 2a might be coordinated to
the metal, 1,2-bis(diphenylphosphino)ethane was added at the end
of the room temperature reaction to release the N,P ligand in its free
Our group [11e13] and others [14] have investigated reactions of
CPCs with lithium and potassium phosphides to form amino-
phosphines and related bidentate ligands (Scheme 1). All CPCs used
in these studies contained an (sp2)CePd bond. In this paper, we
* Corresponding author.
E-mail address: irina.smoliakova@und.edu (I.P. Smoliakova).
http://dx.doi.org/10.1016/j.jorganchem.2015.07.023
0022-328X/© 2015 Elsevier B.V. All rights reserved.

14
G.C. Dickmu et al. / Journal of Organometallic Chemistry 797 (2015) 13e20
Scheme 1. Formation of bidentate ligands by reacting MPPh2 with dimeric CPCs.
form. The yield, indeed, was improved, but not significantly (28%).
CPC 1a was also reacted in THF with 1 equiv. of KPPh2. As in the
previously reported reactions of metal phosphides with CPCs hav-
ing an (sp2)CePd bond [12], no phosphine 2a was formed and only
complex 3a was isolated (Scheme 2). The best yield of this complex
(31%) was obtained when the reaction time was shortened to 1 h.
Then, the reaction of CPC 1a with 4.5 equiv. of KPPh2 (THF, 18 h,
rt) was performed using ethyl acetate instead of halogenated sol-
vents on the separation step. This modification allowed for isolation
of phosphine 2a in 17% yield and complex 4a in 24% yield. The latter
compound presumably has a dimeric structure with two PPh2
bridges (Scheme 2). Attempted purification of complex 4a using
Scheme 3. Proposed reaction of dimer 4a with phosphine 2a.
preparative TLC and CH2Cl2 as the eluent provided the
complex 3a in 16%. The 31P{1H} NMR spectrum of one of the frac-
tions contained the singlet of complex 4a at
ꢀ64.7 ppm [in C6D6
relative to P(OEt)3] and two doublets, 21.8 and 113.5 ppm,
m-Cl-m-PPh2
d
d
JP,P ¼ 36 Hz. We hypothesize that these doublets belong to com-
pound 5a, which can be formed by reacting free phosphine 2a with
complex 4a (Scheme 3). The 31P{1H} NMR chemical shift of
123.2 ppm has been reported for complexes with the PAr2 group as
a terminal ligand bonded to Pd(II) [16] (cf. the chemical shift
of ꢀ7.8 ppm for the terminal PPh2 ligand bonded to Pt [17]), while
the chemical shifts in a range of 20e35 ppm are typical for tertiary
phosphines bonded to Pd(II) as terminal ligands [11,18]. The value
of the coupling constant suggests [18e20] that there are two
phosphorus atoms in complex 5a that are cis to each other. Ac-
cording to the transphobia concept [21], complexes of type 5 are
expected to have a terminal PPh2 group cis to the CH2 fragment of
the cyclopalladated ligand. Thus, we suggest that the diphosphido-
bridged complexes of type 4 can react with other ligands, including
compound 2a, to form mononuclear complexes of type 5.
Scheme 4. Reactions of the fenchone-derived CPC 1b with KPPh2.
slower than that from CPC 1a using 4.5 equiv. of KPPh2 in the same
solvent (31P{1H} NMR data).
Then we studied the fenchone-derived CPC 1b [22] in reactions
with KPPh2. The reaction of CPC 1b with 4.5 equiv. of KPPh2 in THF
furnished the enantiopure N,P ligand 2b in 51% yield (Scheme 4).
Using 1 equiv. of KPPh2, CPC 1b was converted to the
bridged derivative 3b in 56% yield. 1H, 13C{1H} and 31P{1H} NMR
data for complex 3b suggest that this and other -Cl- -PPh2-
m-Cl-m-PPh2-
m
m
bridged CPCs reported in the literature [11e13], as well as the
others described in this study, exist in solutions as single isomers
with trans-N,P geometry.
The next complex studied was the oxazoline-derived dimer 1c,
synthesis of which was described previously [5,23]. Using standard
conditions (rt, 18 h, 4.5 equiv. of KPPh2), three new complexes were
obtained: 3c, 4c and 6c (Scheme 5). No traces of the desired
To test whether the
m-Cl-m-PPh2 complex 3a could be converted
to its di- -PPh2 analog 4a and/or phosphine 2a, it was reacted with
m
1 equiv. of KPPh2. Two compounds were isolated after preparative
TLC: free N,P ligand 2a in 23% yield and complex 4a in 14% yield.
Next, the di-m-PPh2 CPC 4a was converted to compound 2a in 27%
yield by reaction with 2.5 equiv. of KPPh2 in THF (rt, 96 h). It is
phosphino-oxazoline 2c (
d
ꢀ37.8 ppm in CDCl3 relative to P(OEt)3)
[24], Fig. 1) was detected either in the 31P{1H} NMR spectrum of the
reaction mixture or in the spectra of the fractions obtained after
chromatographic separation. As in the case of the camphor-based
noteworthy that the formation of the N,P ligand 2a from CPC 4a was
Scheme 2. Reaction of CPC 1a with KPPh2.

G.C. Dickmu et al. / Journal of Organometallic Chemistry 797 (2015) 13e20
15
Scheme 5. Reaction of CPC 1c with KPPh2.
complex 4a, the oxazoline-derived analog 4c was unstable on SiO2
in the presence of CH2Cl2 and provided two chloro-containing
complexes 3c and 6c in 14 and 8% yield, respectively.
The 8-methylquinoline-derived complex 1d [25] differs from
CPCs 1aec by having a benzylic carbon bonded to the metal. Re-
actions of CPC 1d with 4.5 equiv. of KPPh2 at rt gave only 8-
methylquinoline (7d, Scheme 6). The isolation of free preligands
was previously reported in KPPh2 reactions with CPCs containing
an (sp2)CePd bond [13] as well as in the Pd-catalyzed phosphina-
tion reactions of aryl triflates with PPh3 [26]. The formation of such
Scheme 6. Reactions of CPCs 1d with KPPh2.
products can be explained by
b-hydride elimination of the
alkoxide-containing Pd(II) intermediate, which could be formed
after the adventitious cleavage of a CeO bond in THF by the
phosphide [11,13].
When 1 equiv. of KPPh2 was used in the reaction, the
PPh2-brigded derivative 3d was isolated in 56% (Scheme 7). The 31
{1H} NMR spectrum of complex 3d had a singlet at
m
-Cl-
m
-
P
d
10.2 ppm
[CDCl3 relative to P(OEt)3] and matched the data for this compound
prepared by a different method [24].
Scheme 7. Reaction of CPC
m-OAc-1d with 4.5 equiv. of KPPh2.
Complex 1d had a limited solubility in THF. The use of the more
soluble compound
m-OAc-1d in the same reaction provided a
mixture of phosphine 2d and its oxide 8d. In the next experiment,
air was bubbled through the reaction mixture before purification,
and oxide 8d was isolated in 21% (Scheme 7). This reaction is the
first example of converting acetato-bridged CPCs to the corre-
sponding phosphines (or phosphine oxides) using metal
phosphides.
Scheme 8. Formation of compound 7e in the reaction of CPC 1e with KPPh2.
It was of interest to investigate KPPh2 reactivity toward CPCs
with donor atoms other than nitrogen. The trimesitylphosphine-
derived complex 1e [27] reacted with 4.5 equiv. of KPPh2 at rt to
provide only the free preligand 7e (Scheme 8).
Reactions of KPPh2 with two tri-ortho-tolylphosphine-derived
complexes, dichloro-bridged dimer 1f and its acetato-bridged
chloro-bridged analog provided only traces of the phosphination
product 8f. According to 31P NMR data, only one of the two phos-
phino groups in the product was oxidized. In both reactions, along
with compound 8f, tri-ortho-tolylphosphine 7f was isolated as well
(Scheme 9).
analog
m-OAc-1f [28] were investigated as well. In all experi-
The reactivity of the CS CPC 1g [29] toward KPPh2 was also
studied. The complex reacted with 4.5 equiv. of the phosphide to
ments with these two CPCs, air was bubbled into the reaction
mixtures before purification to ensure oxidation of the phosphine
product. Reaction of complex 1f furnished phosphine oxide 8f in
20% yield (Scheme 10). In contrast to the KPPh2 reactions with the
8-methylquinoline-derived CPCs, the use of m-OAc-1f instead of its
Fig. 1. Structure of compound 2c.
Scheme 9. Reaction of complexes 1f and m-OAc-1f with KPPh2.

16
G.C. Dickmu et al. / Journal of Organometallic Chemistry 797 (2015) 13e20
of complexes 3a,c confirmed a 1:2 ratio of the PPh2 group and
cyclopalladated ligands in their structures. The elemental compo-
sition and purity of these compounds were confirmed by satisfac-
tory elemental analysis.
Di-m-PPh2 complexes of Pd(II) and especially Pt(II) are well
known [19,20,34,35]. However, to the best of our knowledge, only
one cyclometallated derivative of this type has been reported, the
Pt(II) complex derived from 7,8-benzoquinoline [36]. Unfortu-
nately, only the X-ray crystallographic data for this compound are
Scheme 10. Reaction of CPC 1g with KPPh2.
provide product 2g in low yield. Because of the rapid conversion of
phosphine 2g to the corresponding oxide 8g, the crude product was
oxidized before preparative TLC. The best yield of the phosphine
oxide was 22%. It is noteworthy that a significant amount of the free
sulfide 7g was isolated in all reactions of CPC 1g (Scheme 10).
available. The 31P{1H} NMR spectra of known di-
m-PPh2 Pd(II)
complexes usually have the signals of the bridging PPh2 group
between ꢀ100 and ꢀ140 ppm [19,20,34,35,37]. We were able to
isolate two complexes, 4a,c, which presumably have dimeric
cyclopalladated structure with two bridging PPh2 ligands. The 1H
NMR spectrum of the oxazoline-derived complex 4c suggests a 1:1
ratio of the PPh2 fragment and the cyclopalladated ligand. The 31P
{1H} NMR spectrum of the same compound in CDCl3 exhibited a
2.2. Structure confirmation
According to the literature [30], non-coordinated tertiary
phosphines provide 31P{1H} NMR signals in the ꢀ70 to þ70 ppm
interval (relative to H3PO4), diphenyl-substituted tertiary phos-
phines give signals with negative chemical shift values, and signals
of phosphine oxides usually have positive chemical shift values
between 10 and 30 ppm. The spectra of phosphines 2a,b contained
a singlet at ꢀ23.2 and ꢀ37.1 ppm [relative to P(OEt)3], respectively.
These phosphines were slowly, within a week, oxidized by oxygen
lone singlet at
the anti configuration of the cyclopalladated ligands. The 13C{1H}
NMR signal of the CH2Pd fragment in 4c appeared at 42.2 ppm as a
d
ꢀ85.1 ppm (ꢀ72.5 ppm in C6D6), which suggests
d
triplet with JC,P equal to 55.1 Hz. Unfortunately, the camphor-
derived complex 4a could not be obtained in the pure form to
allow its complete characterization by NMR spectroscopy. The 1H
NMR spectrum of this compound was too complex to assign all
signals; however, the signal integration suggested a 1:1 ratio of the
PPh2 fragment and the cyclopalladated ligand. The only reliable
in air to give the corresponding phosphine oxides (
15.0 ppm, respectively). 31P{1H} NMR spectra of phosphine oxides
8d,g exhibited singlets at 16.5 and 15.0 ppm, respectively,
d 15.1 and
spectroscopic data for this complex that can be reported are its 31
{1H} NMR signal at
ꢀ64.8 ppm in C6D6 and -76.9 ppm in CDCl3.
P
d
d
whereas the spectrum of product 8f with two phosphorus atoms
We suggest that complex 6c has a trinuclear structure with both
Cl and PPh2 acting as the bridging ligands. The elemental compo-
sition of the unusual complex was supported by a satisfactory
elemental analysis. The 1H NMR spectrum proved a 1:1 ratio of the
PPh2 group and the cyclopalladated ligand in the structure. The 1:1
ratio of the PPh2 ligand and the cyclopalladated oxazoline moiety
was also evident for di-phosphido-bridged complex 4c; however,
1H, 13C{1H} and 31P{1H} NMR spectra of 4c and 6c were quite
different. The 31P{1H} NMR spectrum of 6c had only one signal at
contained two doublets at
d
ꢀ45.1 and 15.4 ppm (4JP,P ¼ 9.2 Hz).
1H and 13C{1H} NMR signals of the CH2P fragment in compounds
2a,b and 8a,d,f,g displayed JH,P and JC,P coupling constants. Dia-
stereotopic hydrogens of the CH2P group in 2a,b and 8a provided
two doublets of doublets between
signal of the PCH2 group in oxides 8d,f,g appeared as a doublet
d
2.15 and 3.06 ppm. The 1H NMR
between
d 4.00 and 4.56 ppm. The values of the coupling constant
2JH,P for phosphines 2a,b were 3.5 and 4.1 Hz, while those for oxides
8a,d,f,g were much larger: 16.0, 14.2, 9.6 and 14.1 Hz, respectively.
The difference in the values of coupling constants when comparing
phosphines to phosphine oxides was especially noticeable in 13C
d
10.3 ppm. This chemical shift value is within the range reported
[12] or observed in this study for the corresponding dinuclear -Cl-
-PPh2 complexes of type 3. The 13C{1H} NMR signals of the CH2Pd
m
m
{1H} NMR spectra. The CH2P group in phosphines 2a,b gave a
fragment in the trinuclear complex 6c and its binuclear analog 3c
appeared as singlets, suggesting that the CH2 group is cis to the
PPh2 ligand in both compounds.
1
doublet at
d
27.5 and 30.7 ppm with JC,P equal to 18 and 13 Hz,
respectively. The 13C{1H} NMR signal of the same group in oxides
9a,d,f,g appeared between 27.3 and 36.6 ppm and displayed the
d
coupling constant 1JC,P in a range of 67e73 Hz. The oxidation of the
phosphino group in compounds 8a,d,f,g was also confirmed by IR
spectroscopy. IR spectra of these compounds had an absorption
band at 1187ꢀ1199 cm-1 assigned to the stretching vibrations of the
P]O group [31]. The elemental composition of phosphines 2a,b
and phosphine oxides 8d,f,g was confirmed by HRMS data.
Pd(II) complexes with both a chloro and phosphido bridge are
rather uncommon in the literature [11,12,32,33]. Moreover, there
are only two known cyclopalladated complexes of this type
[11,12,33]. Three isomers can be predicted for such complexes;
however, it was shown that in the solid form [33] and in a solution
[11], they exist as syn isomers with the trans-N,P ligand configu-
3. Conclusions
Dimeric cyclopalladated complexes of the C,N, C,P and C,S type
and containing an (sp3)CePd bond reacted with KPPh2 to provide
several products types. The main product structure depended on
the molar equivalents of KPPh2 used in the reaction. When
4.5 equiv. of KPPh2 were applied, the majority of CPCs provided
either phosphine 2 or phosphine oxide 8. In spite of low yields
(20e51%) of the desired phosphination products with an (sp3)
CePPh2 bond and the use of expensive palladium, this method is
presently the only reported two-step sequence for the synthesis of
such compounds from readily available substrates, i.e., preligands
of type 7. It appears that CPCs with an (sp3)CePd bond are some-
what less reactive toward KPPh2 than their analogs with an (sp2)
CePd bond. A diphosphido-bridged cyclopalladated complex, 4c,
was for the first time isolated and fully characterized by 1H, 13C{1H}
and 31P{1H} NMR spectroscopy. Using the knowledge obtained in
our studies of stoichiometric reactions of CPCs with metal phos-
phides, we are currently investigating related Pd-catalyzed
transformations.
ration. Two m-Cl-m-PPh2 Pd(II) complexes 3a,c presumably have a
syn configuration with the PPh2 bridging ligand trans to both ni-
trogen atoms. The 31P{1H} NMR spectra of CPCs 3a,c in CDCl3
exhibited singlets at
d
4.9 and ꢀ1.9 ppm, respectively. In the 13C{1H}
NMR spectra of these complexes, the signal of the CH2Pd fragment
appeared as a doublet (2JC,P ¼ 2.2 Hz) at 19.4 ppm and as a singlet at
33 ppm, respectively. For comparison, the reported complex of this
type synthesized from N,N-dimethylbenzylamine provided the 31
P
NMR signal at
d
25.1 ppm (2JC,P ¼ 1.8 Hz) [11]. The 1H NMR spectra

G.C. Dickmu et al. / Journal of Organometallic Chemistry 797 (2015) 13e20
17
4. Experimental
31P{1H} NMR (CDCl3,
d
, ppm): ꢀ36.9. 31P{1H} NMR (C6D6,
d,
ppm): ꢀ23.2. HRMS: [M þ H]þ calcd for C23H28NOP 366.1981, found
4.1. General methods and materials
366.1979.
Routine 1H (500 MHz), 13C{1H} (126 MHz), and 31P{1H}
(202 MHz) as well as DEPT, COSY, and HSQC NMR spectra were
recorded on a Bruker AVANCE 500 NMR spectrometer. Chemical
shifts are reported in ppm with SiMe4 as an internal standard (1H
and 13C) or P(OEt)3 as an external standard (31P). Spinespin
coupling constants, J, are given in Hz. Spectra were recorded in
CDCl3 unless stated otherwise. Melting points were measured on a
Laboratory Devices Mel-Temp apparatus and are uncorrected. Op-
tical rotations were measured at rt on a Rudolph Autopol III auto-
matic polarimeter. Analytical TLC was performed on Whatman
silica gel 60 (F254) 250 precoated plates. Preparative TLC was carried
out using 200 ꢂ 250 mm glass plates with an unfixed layer of Merck
silica gel 60 (230 mesh) containing ca. 5% of silica gel with fluo-
rescent indicator (Aldrich). Compounds were visualized on TLC
plates using UV light (254 nm) and/or iodine stain. Methoxyamine
hydrochloride was purchased from Alfa Aesar, D-camphor from
Fisher Scientific. All other reagents were acquired from Sigma-
Aldrich and used as purchased. Pd(OAc)2 was purified by dissolv-
ing in hot benzene, filtering the solution and removing the solvent
on a rotavapor. NaOAc and Pd(OAc)2 were dried in vacuum prior to
use. Benzene, CH2Cl2 and hexane were purified by distillation over
CaH2. Toluene and THF were dried by refluxing over K/benzophe-
none ketyl and distilled under Ar immediately before starting a
reaction.
4.3.2. (R,R)-m-Chloro-m-(diphenylphosphido)bis{[2-
(methoxyimino)-7,7-dimethylbicyclo[2.2.1]heptyl]methyl-C,N}
dipalladium(II) (3a)
The reaction was performed as described above for 2a except
that 1 equiv. of KPPh2 was used and the reaction time was 1 h. After
solvent removal, the crude product was dissolved in ethyl acetate
(2 mL) and separated into several fractions using preparative TLC
(10:1 hexane‒ethyl acetate). Fraction 2 corresponded to complex
3a (0.0198 g, 0.0249 mmol, 31%, orange solid). Mp: 194e196 ꢁC; Rf
22
22
0.50 (10:1 hexane‒ethyl acetate); [
0.0650, EtOH). IR (Nujol mull,
, cmꢀ1): 1674 (C]N). 1H NMR (
ppm): 0.62 (s, 3H, CH3), 0.72 (s, 3H, CH3), 0.74 (m, 1H, PdCHA), 1.27
a
]
ꢀ189, [
a
]
ꢀ-190 (c
D
546
n
d,
3
2
3
(ddd, 1H, J5endo,6endo ¼ 13, J5endo,5exo ¼ 9.6, J5endo,6exo ¼ 4.3,
2
H(5endo)), 1.39 (d, 1H, JH,H
¼
10, PdCHB), 1.64 (td, 1H,
2J6exo,6endo ¼ 3J6endo,5endo ¼ 13, 3J6endo,5exo ¼ 4.5, H(6endo)), 1.79 (m,
1H, H(5exo)), 1.91 (d, 1H, 2J3endo,3exo ¼ 19, H(3endo)), 1.96 (ddd, 1H,
2J6exo,6endo ¼ 13, 3J6exo,5exo ¼ 9.6, 3J6exo,5endo ¼ 4.3, H(6exo)), 1.99 (t,
3
2
1H, J4,5exo
¼
3J4,3exo ¼ 4, H(4)), 2.37 (dt, 1H, J3exo,3endo ¼ 19,
3J3exo,4 ¼ 4J3exo,5exo ¼ 4, H(3exo)), 3.97 (s, 3H, OCH3), 7.30 (m, 6H, m-
and p-PPh), 7.84 (m, 4H, o-PPh). 13C{1H} NMR (
d, ppm): 18.5 and
20.2 (two CH3), 19.4 (d, 1JC,P ¼ 2.2, PCH2), 27.3 (CH2, C(5)), 33.4 (CH2,
C(3)), 33.8 (CH2, C(6)), 46.8 (CH, C(4)), 48.2 (quat. C, C(7)), 62.7
3
(OCH3), 65.9 (quat. C, C(1)), 127.9 (CH, d, JC,P ¼ 10, m-PPh), 128.5
(CH, d, 4JC,P ¼ 2.2, p-PPh),134.4 (CH, d, 2JC,P ¼ 12, o-PPh),138.3 (quat.
C, d, 1JC,P ¼ 32, ipso-PPh), 186.1 (quat. C, C]N). 31P{1H} NMR (CDCl3,
d
, ppm): 4.9; 31P{1H} NMR (C6D6,
d, ppm): 18.0. Anal. Calcd for
4.2. Synthesis of the starting compounds 1aeg
C
34H46ClN2O2PPd2: C, 51.43; H, 5.84; N, 3.53%. Found: C, 51.14; H,
Complexes 1aeg were synthesized using published procedures
[5,15,22,25,27e29]. The NMR spectra of the obtained compounds
matched those reported in the literature.
5.85; N, 3.49%.
4.3.3. (R,R)-Di-m-(diphenylphosphido)bis{[2-(methoxyimino)-7,7-
dimethylbicyclo[2.2.1]heptyl]methyl-C,N}dipalladium(II) (4a)
4.3. Synthesis and characterization of new compounds
The reaction was performed as described above for 2a. The
purification by preparative TLC was performed using 5:1 hexane‒
ethyl acetate as an eluent. The use of halogenated solvents, such as
CH2Cl2 and CHCl3, was avoided during all steps of the product
purification. The upper fraction on the TLC plate corresponded to
the product (0.0163 g, 0.0173 mmol, ca. 26%, brown solid). 31P{1H}
4.3.1. (R,R)-1-{(Diphenylphosphino)methyl}-7,7-dimethylbicyclo
[2.2.1]heptan-2-one O-Methyloxime (2a)
CPC 1a (0.0723 g, 0.112 mmol) was added to a 25-mL Schlenk
flask containing a magnetic stirring bar. The flask was evacuated
and filled with Ar 5 times. Abs. THF (15 mL) was then added using a
syringe followed by a 0.5 M solution of KPPh2 (1 mL, 0.5 mmol).
During the dropwise addition of KPPh2 for 5 min, the yellow so-
lution turned dark red. The mixture was stirred at rt for 18 h in Ar.
The Schlenk flask was then placed on a rotavapor to remove THF.
The dark-red solid residue was dissolved in CH2Cl2 (2 mL) and
quickly separated into several fractions using preparative TLC (10:1
hexane‒ethyl acetate). Fraction 3 corresponded to the product
NMR (CDCl3,
d
, ppm): ꢀ76.9; 31P{1H} NMR (C6D6,
, ppm): ꢀ64.3.
d
4.3.4. (R,R)-1-{(Diphenyloxophosphino)methyl}-7,7-
dimethylbicyclo[2.2.1]heptan-2-one O-Methyloxime (8a)
Phosphine 2a was exposed to the air to give the corresponding
23
oxide as an orange-yellow oil in a quantitative yield. [
a
]
ꢀ18,
D
23
[a
]
ꢀ13 (c 0.099, EtOH). Rf 0.57 (5:3 hexane‒acetone). IR
546
22
22
(0.0492 g, 0.135 mmol, 21%, colorless oil). [
a
]
D þ154, [
a
]
546 þ173
(CH2Cl2, n d, ppm): 0.81
, cmꢀ1): 1671 (C]N), 1184 (P]O). 1H NMR (
(c 0.0460, EtOH). Rf 0.63 (10:1 hexane‒ethyl acetate). 1H NMR (
d
,
(s, 3H, CH3), 1.04 (s, 3H, CH3), 1.12 (m, 1H, H(5endo)), 1.30 (m, 1H,
H(6endo)), 1.82 (m, 2H, H(5exo), H(4)), 1.88 (d, 1H, 2J3endo,3exo ¼ 18,
H(3endo)), 2.15 (t,1H, 2JH,H ¼ 3JH,P ¼ 16, PCHA), 2.40 (m, 2H, H(6exo),
H(3exo)), 3.06 (dd, 1H, 2JH,H ¼ 3JH,P ¼ 16, PCHB), 3.72 (s, 3H, OCH3),
7.45 (m, 6H, o- and p-PPh), 7.77 (m, 2H, m-PPhA), 7.95 (m, 2H, m-
ppm): 0.83 (s, 3H, CH3), 0.94 (s, 3H, CH3), 1.20 (m, 1H, H(5endo)),
1.64 (m, 1H, H(6endo)), 1.77 (m, 2H, H(5exo), H(6exo)), 1.84 (m, 1H,
2
H(4)), 1.95 (d, 1H, J3endo,3exo ¼ 17.6, H(3endo)), 2.15 (dd, 1H,
3
2
2JH,H ¼ 15.0, JH,P ¼ 4.1, PCHA), 2.48 (ddd, 1H, J3exo,3endo ¼ 17.6,
3J3exo,4
z
4J3exo,5exo z 4.3, H(3exo)), 2.52 (dd, 1H, JH,H ¼ 15.0,
PPhB). 13C{1H} NMR (
d, ppm): 19.6 and 19.9 (two CH3), 27.3 (d,
2
3JH,P ¼ 4.1, PCHB), 3.76 (s, 3H, OCH3), 7.32 (m, 6H, m- and p-PPh),
1JC,P ¼ 73, PCH2), 28.0 (CH2, C(5)), 29.4 (CH2, d, 3JC,P ¼ 5.1, C(6)), 33.8
3
7.51 (m, 4H, o-PPh). 13C{1H} NMR (
d
, ppm): 19.8 and 20.1 (two CH3),
(CH2, C(3)), 43.2 (CH, C(4)), 50.3 (quat. C, d, JC,P ¼ 4.6, C(7)), 53.2
27.5 (d, 1JC,P ¼ 18, PCH2), 27.8 (CH2, C(5)), 30.9 (CH2, d, JC,P ¼ 12,
(quat. C, d, 2JC,P ¼ 4.9, C(1)), 61.7 (OCH3), 128.6 (CH, d, 2JC,P ¼ 12, o-
3
3
2
3
C(6)), 33.7 (CH2, C(3)), 44.2 (CH, C(4)), 49.8 (quat. C, d, JC,P ¼ 3.9,
PPhA), 128.8 (CH, d, JC,P ¼ 12, o-PPhB), 130.8 (CH, d, JC,P ¼ 8.9, m-
2
C(7)), 54.6 (quat. C, d, JC,P ¼ 14, C(1)), 61.8 (OCH3), 128.27, 128.47,
PPhA),131.6 (CH, br. s, p-PPh),131.7 (CH, d, 3JC,P ¼ 9.4, m-PPhB),134.9
128.52, 128.76, 128.81 (all CH, m- and p-PPh; the signal at
128.81 ppm has a double intensity), 133.0 (CH, d, 2JC,P ¼ 19, o-PPhA),
(quat. C, d, 1JC,P ¼ 98, ipso-PPhA), 136.6 (quat. C, d, 1JC,P ¼ 99, ipso-
PPhB), 167.5 (quat. C, d, JC,P ¼ 5.3, C]N). 31P{1H} NMR (CDCl3,
d,
4
133.7 (CH, d, JC,P ¼ 20, o-PPhB), 141.2 (quat. C, d, JC,P ¼ 15, ipso-
ppm): 15.1. 31P{1H} NMR (C6D6,
d
, ppm): 25.0. HRMS: [M þ H]þ
2
1
PPhA), 141.3 (quat. C, d, 1JC,P ¼ 17, ipso-PPhB), 167.9 (quat. C, C]N).
calcd for C23H28NO2P 382.1894, found 382.1894.

18
G.C. Dickmu et al. / Journal of Organometallic Chemistry 797 (2015) 13e20
4.3.5. (S,S)-1-{(Diphenylphosphino)methyl}-3,3-dimethylbicyclo
[2.2.1]heptan-2-one O-Methyloxime (2b)
The reaction was performed as described above for 2a using
complex 1b (0.0794 g, 0.123 mmol). The reaction mixture was
separated into several fractions using preparative TLC (10:1 hex-
complex 6c: Rf 0.07 (benzene), 0.70 (5:1 benzeneeacetone); 1H
NMR (d, ppm, C6D6): 1.05 and 1.24 (two s, 6H each, two (CH3)2C),
1.32 (s, 2H, PdCH2), 3.31 (s, 2H, OCH2), 6.85 (t, 4H, 3J ¼ 7.3, m-PPh),
6.94 (t, 2H, 3J ¼ 7.3, p-PPh), 7.58 (m, 4H, o-PPh); 13C{1H} NMR (
d,
ppm, C6D6): 27.9 and 28.4 (two (CH3)2C), 33.7 (CH2Pd), 42.2 and
3
ane‒ethyl acetate). Fraction 3 corresponded to compound 2b
66.9 (two C(CH3)2), 81.9 (OCH2), 127.9 (t, JCP ¼ 5.0, m-PPh), 128.9
24
2
(0.0461 g, 0.126 mmol, 51%, colorless oil).
[
a]
þ138,
(p-PPh), 135.0 (t, JCP ¼ 7.5, o-PPh), 135.4 (t, 1JCP ¼ 17.0, ipso-PPh),
D
24
24
[
a]
þ171, [
a]
þ246 (c 0.150, EtOH). Rf 0.65 (10:1 hexane‒
182.1 (C]N); 31P{1H} NMR ( , ppm, CDCl3): 10.3; 31P{1H} NMR (
d d,
546
435
ethyl acetate). 1H NMR (
d
, ppm): 1.19, 1.25 (two s, 6H, 2CH3), 1.31 (d,
ppm, C6D6): 23.3. Anal. Calcd for C42H52Cl2N2O2P2Pd2: C, 47.19; H,
4.90; N, 2.62%. Found: C, 47.32; H, 4.99; N, 2.58%.
2
1H, J7A,7B ¼ 10.1, H(7A)), 1.42 (m, 1H, H(6endo)), 1.50 (m, 1H,
H(5endo)), 1.58 (br. d, 1H, H(7B)), 1.75 (m, 2H, H(4), H(5exo)), 1.92
2
3
(tq, 1H, J6exo,6endo
¼
3J6exo,5endo ¼ 12.0, J6exo,5exo
z
4J6exo,P z 1.8,
4.3.8. Di-m-(diphenylphosphido)bis{2-[2-(4,4-dimethyl-2-oxazolin-
2-yl)-2-methyl]propyl-C,N}dipalladium(II) (4c)
H(6exo)), 2.46 (dd, 1H, 2JH,H ¼ 14.7, 2JH,P ¼ 3.5, PCHA), 2.59 (dd, 1H,
2JH,H ¼ 14.7, 2JH,P ¼ 4.1, PCHB), 3.73 (s, 3H, OCH3), 7.30 (m, 6H, m- and
The complex was obtained as a bright orange solid using the
reaction conditions described for complexes 3c and 6c except for
the purification step. After solvent removal from the reaction
mixture, freshly distilled CH2Cl2 (ca. 1.5 mL) was added to the solid
residue. The part of the reaction mixture soluble in CH2Cl2 was then
purified by preparative TLC (3:1 benzeneeacetone) to give 3c and
6c. The remaining reaction mixture (which was insoluble in
CH2CH2) was dissolved in benzene. The solution was filtered and
then the solvent was removed on a rotary evaporator yielding an
orange solid. This solid was transferred to a filter, rinsed with
hexane and dried under vacuum. Yield 23.9 mg (36%). Rf 0.97
p-PPh), 7.47 (m, 4H, o-PPh). 13C{1H} NMR (
d, ppm): 22.5 and 23.1
(two CH3), 25.0 (CH2, C(5)), 30.7 (d, 1JC,P ¼ 13.1, PCH2), 33.3 (d, CH2,
3JC,P ¼ 9.2, C(6)), 41.2 (CH2, C(7)), 44.3 (CH, C(4)), 48.3 (d, C, C(3)),
52.6 (d, C, 2JC,P ¼ 16.7, C(1)), 61.2 (OCH3), 128.22, 128.27, 128.32 (m-
and p-PPh), 132.8 (d, JC,P ¼ 19.2, o-PPhA), 133.0 (d, JC,P ¼ 19.3, o-
2
2
PPhB), 139.9 (d, 1JC,P ¼ 12.6, ipso-PPhA), 140.0 (d, 1JC,P ¼ 10.8, ipso-
PPhB), 171.9 (C]N). 31P{1H} NMR (CDCl3,
d
, ppm): ꢀ37.1. HRMS:
[M þ H]þ calcd for C23H28NOP 366.1981, found 366.1964.
4.3.6. (S,S)-m-Chloro-m-(diphenylphosphido)bis{[2-
(methoxyimino)-3,3-dimethylbicyclo[2.2.1]heptyl]methyl-C,N}
dipalladium(II) (3b)
The reaction was performed as described above for the prepa-
ration of 3a using complex 1b (0.0817 g, 0.1268 mmol). The reaction
mixture was separated into several fractions using preparative TLC
(10:1 hexane‒ethyl acetate). Fraction 2 corresponded to complex
(benzene); 0.70 (hexane). M.p. 152e155 ꢁC (dec.). IR (CH2Cl2,
n,
cmꢀ1): 1632 s (C]N). 1H NMR (
d
, ppm, C6D6): 0.57 and 1.31 (two s,
6H each, two (CH3)2C), 1.65 (s, 2H, PdCH2), 3.37 (s, 2H, OCH2), 7.06
(m, 2H, p-PPh), 7.11(m, 4H, m-PPh), 8.13 (m, 4H, o-PPh). 13C{1H}
NMR (
d
, ppm, C6D6): 27.3 and 30.0 (two (CH3)2C), 42.2 (t, 2JCP ¼ 55.1,
CH2Pd), 43.0 and 65.8 (two quat. C, two C(CH3)2), 81.7 (OCH2), 127.3
23
23
3b (0.0180 g, 0.0227 mmol, 56%, orange solid). [
a
]
D ꢀ121, [
a]
546
(CH, p-PPh),127.8 (CH, t, 3JCP ¼ 3.6, m-PPh),136.1 (CH, t, 2JCP ¼ 5.6, o-
23
ꢀ147, [
a
]
435 ꢀ204 (c 0.222, EtOH). Mp: 209e211 ꢁC; Rf 0.55 (10:1
PPh), 142.5 (quat. C, t, 1JCP ¼ 3.0, ipso-PPh), 184.9 (quat. C, C]N). 31
P
hexane‒ethyl acetate). 1H NMR (
d
, ppm): 1.05 (dd, 1H, JH,H ¼ 9.6,
2
{1H} NMR (
d
, ppm, CDCl3): ꢀ85.1; 31P{1H} NMR (
d, ppm, C6D6):
3JH,P ¼ 4.8, PdCHA), 1.14, 1.20 (two s, 6H, 2CH3), 1.17 (m, 1H, H(7A)),
1.53 (m, 2H, H(6endo), 5endo)), 1.63 (m, 2H, H(7B), PdCHB), 1.80 (m,
1H, H(5exo)), 1.91 (m, 2H, H(4), H(6exo)), 3.93 (s, 3H, OCH3), 7.29
ꢀ72.5.
(m, 6H, m- and p-PPh), 7.82 (m, 4H, o-PPh). 13C{1H} NMR (
d
, ppm):
4.3.9. 8-[(Diphenyloxophosphino)methyl]quinoline (8d)
22.5 and 23.0 (two CH3), 25.6 (CH2, C(5)), 25.7 (PCH2), 35.1 (CH2,
C(6)), 43.4 (CH2, C(7)), 44.0 (C, C(3)), 52.3 (CH, C(4)), 62.6 (OCH3),
Complex 1d (0.1636 g, 0.2659 mmol) was added to an oven dried
Ar-filled 50-mL Schlenk flask containing a magnetic stirring bar.
The flask was evacuated and filled with Ar 5 times. Then abs. THF
(17 mL) was added followed by a 0.5 M solution of KPPh2 in THF
(3.2 mL, 1.6 mmol). During the dropwise addition, the orange so-
lution turned dark red, and then black. The mixture was stirred at rt
for 48 h in Ar. The reaction mixture was then filtered through celite
(h ¼ 1 cm), and the flask with the filtrate was placed on a rotavapor
to remove solvent. The crude product was dissolved in CH2Cl2 and
separated into several fractions using preparative TLC (10:1 ethyl
acetate‒acetone). Fraction 1 corresponded to 8-methylquinoline 7d
(0.0450 g, 0.314 mmol, 48%, colorless oil). Fraction 3 corresponded
to compound 8d (0.0321 g, 0.0231 mmol, 21%, colorless oil). Rf 0.40
3
64.3 (C, C(1)), 127.9, (d, JC,P ¼ 10.2, m-PPh), 128.4 (s, p-PPh), 134.4
(d, 2JC,P ¼ 12.2, o-PPh), 138.6 (d, 1JC,P ¼ 31.1, ipso-PPh), 190.6 (C]N).
31P{1H} NMR (CDCl3,
d,
ppm): 2.2. Anal. Calcd for
C
34H46N2O2PClPd2: C, 51.43; H, 5.84; N, 3.53%. Found: C, 51.30; H,
5.84; N, 3.52%.
4.3.7.
dimethyloxazolin-2-yl)-2-methyl]propyl-C,N}dipalladium(II) (3c)
and di- -chloro- -(diphenylphosphido)bis{2-[2-(4,4-
m-Chloro-m-(diphenylphosphido)bis{2-[2-(4,4-
m
m
dimethyloxazolin-2-yl)-2-methyl]propyl-C,N}tripalladium(II) (6c)
The reaction was performed as described for compound 2a us-
ing CPC 1c (30.2 mg, 0.0512 mmol) as a starting reactant. The re-
action mixture first appeared yellow, then dark red, and finally dark
yellow. The reaction mixture was separated into fractions using
preparative TLC (3:1 benzeneeacetone). Two pure compounds
were isolated: complex 3c as a white solid in 14% yield (5.2 mg) and
complex 6c as a bright yellow solid in 8% yield (2.9 mg). Data for
(10:1 ethyl acetate‒acetone). 1H NMR (
d, ppm): 4.56 (d, 2H,
2JH,P ¼ 14.2, PCH2), 7.28 (t, 1H, 3JH,H ¼ 4.2, arom. H(3)), 7.31 (m, 4H,
3
4
o-PPh), 7.38 (dt, 2H, JH,H ¼ 7.4, JH,H ¼ 1.3, p-PPh), 7.46 (t, 1H,
2JH,P ¼ 15.4, arom. H(6)), 7.64 (d,1H, 3JH,P ¼ 8.2, arom. H(7)), 7.78 (m,
3
5
4H, m-PPh), 8.03 (dd, 1H, JH,H ¼ 8.2, JH,H ¼ 1.6, arom. H(5)), 8.05
(m, 1H, arom. H(4)), 8.76 (dd, 1H, 3JH,H ¼ 4.1, 5JH,H ¼ 1.6, arom. H(2)).
complex 3c: Rf 0.48 (benzene); 1H NMR (
d
, ppm): 1.08 and 1.45 (two
13C{1H} NMR (
d
, ppm): 21.2 (d, JC,P ¼ 67.9, PCH2), 121.2 (s, arom.
1
s, 6H each, two (CH3)2C), 1.21 (d, 2H, 3JH,P ¼ 2.6, PdCH2), 4.06 (s, 2H,
CH(3)), 126.8 (d, 3JC,P ¼ 2.8, arom. CH(6)), 127.2 (d, 4JC,P ¼ 1.0, arom.
OCH2), 7.27 (m, 3H, o- and m-PPh), 7.83 (m, 2H, p-PPh); 13C{1H}
CH(7)), 128.5 (d, JC,P ¼ 11.6, o-PPh), 131.2 (d, JC,P ¼ 7.7, ipso-PPh),
2
2
2
NMR (
d
, ppm): 27.8 and 28.0 (two (CH3)2C), 31.0 (CH2Pd), 41.6 and
131.55 (s, arom. CH(5)), 131.56 (d, JC,P ¼ 9.2, m-PPh), 131.8 (d,
66.2 (two quat. C, two C(CH3)2), 81.8 (OCH2), 127.4 (CH, d, 3JC,P ¼ 9.8,
2JC,P ¼ 2.3, p-PPh), 133.0 (s, arom. C(10)), 133.8 (two s, (s, arom.
2
2
m-PPh), 127.5 (CH, p-PPh), 134.2 (CH, d, JC,P ¼ 11.3, o-PPh), 138.7
CH(8)), 136.6 (s, arom. CH(4)), 146.7 (d, JC,P ¼ 5.5, arom. CH(9)),
(quat. C, d, 1JC,P ¼ 28.9, ipso-PPh), 181.1 (quat. C, C]N); 31P{1H} NMR
149.4 (s, CH, arom. CH(2)). 31P{1H} NMR (CDCl3,
d, ppm): 16.5. IR
(CDCl3,
d
, ppm): ꢀ1.93. Anal. Calcd for C30H42N2O2PClPd2: C, 48.57;
(Nujol mull,
n
, cmꢀ1): 1199 s (P]O). HRMS: [M þ H]þ calcd for
H, 5.71; N, 3.78%. Found: C, 48.77; H, 5.84; N, 3.59%. Data for
C22H19NOP 343.1199, found 344.1108.

G.C. Dickmu et al. / Journal of Organometallic Chemistry 797 (2015) 13e20
19
4.3.10.
C,N)dipalladium (3d)
The reaction was performed as described above for preparation
of 3a using CPC 1d (0.0498 g, 0.0693 mmol). The reaction mixture
was separated into several fractions using preparative TLC (10:1
m
-Chloro-
m
-(diphenylphosphido)bis(8-quinolinylmethyl-
oil). Rf 0.50 (10:1 ethyl acetate‒acetone). 1H NMR (
d
, ppm): 2.04 (s,
3H, CH3), 2.48 (s, 3H, SCH3), 4.24 (d, 2H, 2JH,P ¼ 14.1, PCH2), 7.10 (m,
2H, arom. H(4), H(5)), 7.33 (m, 1H, arom. H(3)), 7.42 (dt, 4H,
4
3
3JH,P
¼
3JH,H ¼ 7.7, JH,H ¼ 2.7, o-PPh), 7.49 (dt, 2H, JH,H ¼ 7.4,
4JH,H ¼ 1.3, p-PPh), 7.72 (dd, 4H, 3JH,H ¼ 7.2, 3JH,H ¼ 7.2, m-PPh). 13
C
benzene‒acetone). Fraction
1
corresponded to complex 3d
{1H} NMR (
d
, ppm): 19.1 (s, CH3), 22.2 (s, SCH3), 36.6 (d, 1JC,P ¼ 67.0,
(0.0258 g, 0.0359 mmol, 56%, orange powder). Mp: 237e239 ꢁC; Rf
PCH2),128.6 (d, 5JC,P ¼ 1.7, arom. CH(5)),128.8 (d, 2JC,P ¼ 11.8, o-PPh),
0.65 (15:1 toluene‒ethyl acetate). 1H NMR (
d, ppm): 3.02 (s, 2H,
129.0 (d, 3JC,P ¼ 4.8, CH(3)), 129.7 (d, 4JC,P ¼ 2.7, arom. CH(4)), 131.7
CH2), 7.35 (m, 6H, m- and p-PPh), 7.40 (t, 1H, 3JH,H ¼ 7.5, arom. CH),
(d, JC,P ¼ 9.1, m-PPh)), 132.1 (d, JC,P ¼ 2.8, p-PPh), 132.7 (s, C(6)),
133.5 (s, C(2)), 136.36 (t, 1JC,P ¼ 9.2, ipso-PPh), 143.5 (s, C(1)). 31P{1H}
3
4
3
3
7.45 (d, 1H, JH,H ¼ 7.0, arom. CH), 7.50 (dd, 1H, JH,H z 8.3,
4JH,H z 4.7, arom. CH), 7.56 (d, 1H, JH,H z 7.7, arom. CH), 8.00 (m,
NMR (CDCl3, d, ppm): 15.03. IR (Nujol mull, n
, cmꢀ1): 1187 s (P]O).
3
4H, o-PPh) 8.25 (dd, 1H, 3JH,H z 8.2, 4JH,H z 1.3, arom. CH), 9.11 (m,
HRMS: [M þ H]þ calcd for C21H22OPS 353.1123, found 353.1005.
1H, arom. CH). 13C{1H} NMR (
d, ppm): 25.7 (CH2, CH2), 120.9 (d,
4JC,P ¼ 2.7, CH), 123.4 (s, CH), 127.5 (s, CH), 127.9, (d, 3JC,P ¼ 10.0, m-
Acknowledgment
PPh), 128.2 (d, 4JC,P ¼ 2.5, CH), 129.0 (s, C), 129.3 (s, p-PPh), 134.1 (d,
2JC,P ¼ 11.9, o-PPh), 137.7 (s, CH), 137.8 (d, JC,P ¼ 32.1, ipso-PPh),
1
The authors acknowledge financial support from the University
of North Dakota and ND EPSCoR through NSF grant No. EPS-0-
0184442. We would also like to thank Dr. V.A. Stepanova for help
with experimental techniques.
146.8 (s, CH), 149.6 (s, C), 151.0 (d, JC,P ¼ 1.9, C). 31P{1H} NMR
4
(CDCl3, d, ppm): 10.2. Anal. Calcd for C32H26N2PClPd2: C, 53.54; H,
3.65; N, 3.90%. Found: C, 53.27; H, 3.80; N, 3.85%.
4.3.11. [2-(Di-ortho-tolylphosphino)benzyl]diphenylphosphine
oxide (8f)
Appendix A. Supplementary data
Complex 1f (0.0690 g, 0.0775 mmol) was added to an oven dried
Ar-filled 25-mL Schlenk flask containing a magnetic stirring bar.
The flask was evacuated and filled with Ar 5 times. Then abs. THF
(10 mL) was added followed by a 0.5 M solution of KPPh2 in THF
(0.7 mL, 0.3 mmol). During the dropwise addition, the yellow so-
lution turned dark red, and then brown. The mixture was stirred at
rt for 48 h in Ar and then 48 h in air. The reaction mixture was then
filtered through celite (h ¼ 1 cm), and the flask with the filtrate was
placed on a rotavapor to remove solvent. The mixture was sepa-
rated into several fractions using preparative TLC (10:1 ethyl ace-
tate‒acetone). Fraction 1 corresponded to tri(O-tolyl)phosphine 7f
(0.001 g, 0.003 mmol, 2%, white powder). Fraction 2 corresponded
to product 8f (0.00147 g, 0.0303 mmol, 20%, pale yellow oil). Rf 0.59
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.jorganchem.2015.07.023.
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The compound was obtained using the procedure described
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20
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