Phosphinidine-palladium complexes for the polymerization and oligomerization of ethylene

Article abstract of DOI:10.1021/om020631x

The phosphinidine-palladium complexes for the polymerization and oligomerization of ethylene were studied. These complexes displayed moderate to high activity (for palladium complexes) in the oligomerization and polymerization of ethylene. It was found th

Full text of DOI:10.1021/om020631x

Organometallics 2002, 21, 5935-5943
5935
P h osp h in id in e-P a lla d iu m Com p lexes for th e
P olym er iza tion a n d Oligom er iza tion of Eth ylen e
Olafs Daugulis, Maurice Brookhart,* and Peter S. White
Department of Chemistry, University of North Carolina at Chapel Hill,
Chapel Hill, North Carolina 27599-3290
Received August 2, 2002
Several cationic palladium complexes containing bulky phosphinidine-imine, phosphini-
dine-sulfide, and imine-sulfide ligands have been prepared. These complexes catalyze the
oligomerization and polymerization of ethylene with moderate to high rates (for palladium
catalysts) and display higher stability compared to diimine-palladium systems.
In tr od u ction
The development of well-defined late-transition metal
catalysts for the polymerization of ethylene and R-olefins
has been the subject of intense recent study.1 Following
the pioneering studies of Wilke,2a Keim,2b and Klabunde
and Ittel2c we disclosed highly versatile Ni(II) and Pd-
(II)-R-diimine-based catalysts of type 1.3a Hindered aryl
groups on the R-diimine nitrogens block the axial
coordination sites and retard chain transfer relative to
propagation, resulting in high molecular weight poly-
mer. These complexes polymerize ethylene, producing
polyethylene with microstructures ranging from almost
linear to hyperbranched depending on the catalyst used
and reaction variables.3b,c Nickel catalysts are stable for
hours at room temperature;3d however, in the case of
palladium catalysts, lowering of reaction temperature
arm of bidentate Pd(II) complexes in the hope of
imparting greater thermal stability to these catalysts.
We report here synthesis and ethylene polymerization
activity of a number of cationic phosphinidine-imine,
phosphinidine-sulfide, and imine-sulfide palladium com-
plexes.
to 5 °C is necessary to achieve living polymerization and
prevent substantial catalyst decomposition.3e
Recently, cationic palladium-diphosphinidenecyclobu-
tene complexes of type 2 were described by Ozawa,
Yoshifuji, and co-workers.4 At 60-100 °C they catalyze
the conversion of ethylene to polyethylene with moder-
ate Mw’s (4000-33 000), high polydispersities (4.2-
14.8), and moderate activities (up to 4500 TO/h at 70
°C). Noteworthy is the exceptional thermal stability of
these complexes. Palladium-diimine catalysts deactivate
at moderate rates at RT,3e and at 70 °C deactivation is
observed within 15 min.4 Since arylphosphinidines and
arylimines possess similar structural features, we sought
to incorporate the phosphinidine functionality into one
Resu lts a n d Discu ssion
1. P d (II) Ca ta lysts In cor p or a tin g P h osp h in i-
d in e-Im in e Liga n d s. The most straightforward modi-
fication of the diimine system was the incorporation of
both a phosphinidine and imine moiety into the cata-
lysts. Starting phosphinidine-imine ligands were pre-
pared taking advantage of elimination methodology
developed by Bickelhaupt et al. for unstabilized phos-
phinidines.5 Imines 3a ,b were deprotonated with LDA,
followed by reaction with Mes*PCl2 (Mes* ) 2,4,6-tri-
tert-butylphenyl). Elimination of HCl from the inter-
mediate chlorophosphines using DBU afforded the
requisite phosphinidine-imine ligands 4a ,b as yellow-
red crystalline solids. In the case of more hindered 4a
it was necessary to use acetonitrile as solvent and
elevated temperatures in the elimination step to obtain
a reasonable conversion to the phosphinidine (Scheme
1).
(1) For recent reviews see: (a) Ittel, S. D.; J ohnson, L. K.; Brookhart,
M. Chem. Rev. 2000, 100, 1169. (b) Britovsek, G. J . P.; Gibson, V. C.;
Wass, D. F. Angew. Chem., Int. Ed. 1999, 38, 428. (c) Mecking, S.
Coord. Chem. Rev. 2000, 203, 325.
(2) (a) Wilke, G. Angew. Chem., Int. Ed. Engl. 1988, 27, 185. (b)
Keim, W.; Kowaldt, F. H.; Goddard, R.; Kru¨ger, C. Angew. Chem., Int.
Ed. Engl. 1978, 17, 466. (c) Klabunde, U.; Ittel, S. D. J . Mol. Catal.
1987, 41, 123.
(3) (a) J ohnson, L. K.; Killian, C. M.; Brookhart, M. J . Am. Chem.
Soc. 1995, 117, 6414. (b) Brookhart, M. S.; J ohnson, L. K.; Killian, C.
M.; Arthur, S. D.; Feldman, J .; McCord, E. F.; McLain, S. J .; Kreutzer,
K. A.; Bennett, M. A.; Coughlin, E. B.; Ittel, S. D.; Parthasarathy, A.;
Tempel, D. J . WO 9623010, 1996. (c) Guan, Z.; Cotts, P. M.; McCord,
E. F.; McLain, S. J . Science 1999, 283, 2059. (d) Gates, D. P.; Svejda,
S. A.; On˜ate, E.; Killian, C. M.; J ohnson, L. K.; White, P. S.; Brookhart,
M. Macromolecules 2000, 33, 2320. (e) Gottfried, A. C.; Brookhart, M.
Macromolecules 2001, 34, 1140.
(5) (a) Klebach, Th. C.; Lourens, R.; Bickelhaupt, F. J . Am. Chem.
Soc. 1978, 100, 4886. (b) van der Knaap, Th. A.; Klebach, Th. C.; Visser,
F.; Bickelhaupt, F.; Ros, P.; Baerends, E. J .; Stam, C. H.; Konijn, M.
Tetrahedron 1984, 40, 765.
(4) Ikeda, S.; Ohhata, F.; Miyoshi, M.; Tanaka, R.; Minami, T.;
Ozawa, F.; Yoshifuji, M. Angew. Chem., Int. Ed. 2000, 39, 4512.
10.1021/om020631x CCC: $22.00 © 2002 American Chemical Society
Publication on Web 11/23/2002

5936 Organometallics, Vol. 21, No. 26, 2002
Daugulis et al.
compared to the free ligands (δP, ppm: 4a , +303.0 ppm;
5a , +268.3; 6a , +267.4 ppm). The magnitude of Me-P
coupling constants suggests that phosphorus is cis to
1
the methyl group (6b, J Me-P, H; 2.6 Hz; 13C, 2.7 Hz;
similar values for 5a ,b and 6a ).6b
A single-crystal X-ray analysis confirmed the struc-
ture of 6a and its geometrical similarity to the corre-
sponding diimine-palladium complexes. The crystal
structure shows a square planar arrangement of the
ligands around the palladium center. As expected from
the spectral data, the methyl group on palladium is
positioned cis to the phosphorus atom, suggesting a
stronger trans-influence8 of the phosphinidine moiety.
The P(1)dC(6) bond length in 6a is slightly shortened
compared to free ligand 4a (1.660(11) vs 1.684(2) Å) and
is comparable to the bond lengths in other phosphini-
dine-palladium complexes.9,10 The Pd-P bond length of
2.183(3) Å is shorter than in palladium-diphosphin-
idenecyclobutane complexes9a,b,d (2.23-2.33 Å) but simi-
lar to Pd-P lengths in palladium complexes of phos-
phinidine-pyridines6b and orthopalladated phosphini-
dines.10 The length of the N(14)dC(7) bond (1.287(15)
Å) is in the standard range for palladium-imine com-
plexes.11 The five-membered chelate ring is planar
within two degrees. N-Aryl and P-aryl groups lie almost
perpendicular to the plane of the five-membered ring
(torsion angles: C(6)-P(1)-C(15)-C(20), 88.0(11)°, C(7)-
N(14)-C(33)-C(38), 96.5(15)°), efficiently blocking the
axial coordination sites (Figure 2).
F igu r e 1. ORTEP view of 4a . Selected interatomic dis-
tances (Å) and angles (deg): P(1)-C(2) ) 1.684(2), P(1)-
C(24) ) 1.85(2), N(5)-C(4) ) 1.288(3), C(4)-C(2) ) 1.484-
(3); C(24)-P(1)-C(2) ) 104.36(9), P(1)-C(2)-C(4) )
116.36(15), C(2)-C(4)-N(5) ) 116.75(18).
Sch em e 1
Sch em e 2
Complexes 6a ,b proved to be ethylene oligomerization
catalysts and were studied at 26 °C and 400 psi
ethylene. Results are summarized in Table 1. A turnover
rate of 23 TO/h was observed for more hindered catalyst
6a in a 3 h run. Decreased hindrance in 6b gave rise to
higher turnover numbers (94 TO/h) with a concurrent
drop of oligomer molecular weight from 670 to 300. The
catalysts are more stable than diimine-Pd complexes at
RT; comparing entries 1 and 2 shows that 6a does not
significantly deactivate in a 15 h run.
In an effort to better understand this system, ethylene
insertion barriers were measured for the less hindered
mesitylimine system 6b. Cationic ethylene complex 7
was generated at -78 °C via the reaction of 5b with
NaB(ArF)4 under excess olefin (20 equiv). Upon warming
to -23 °C, migratory insertion of ethylene into the Pd-
An X-ray structure of the ligand 4a was obtained to
verify the geometry around the CdP and CdN bonds
(Figure 1). As expected, a trans configuration of the
imine and phosphinidine double bonds was observed.
Bond lengths observed in 4a are common for phos-
phaalkenes6 (C(2)dP(1), 1.684(2) Å; C(24)-P(1), 1.850-
(2) Å). The C(24)-P(1)-C(2) angle of 104.36(9)° and
C(24)-P(1)-C(2)-C(4) dihedral angle of -176.1(3)° are
also typical for phosphinidines not bearing two bulky
substituents on the carbon terminus of the PdC bond.6a
Ligands 4a ,b readily displace cod from (cod)PdMeCl7
to give single isomers of the corresponding complexes
5a ,b in good yields. Chloride ion abstraction was ef-
fected by reaction of 5a ,b with NaB(ArF)4 (ArF ) [3,5-
(CF3)2C6H3]) in acetonitrile/dichloromethane, affording
cationic acetonitrile complexes 6a ,b as yellow-red pow-
ders (Scheme 2). The phosphorus chemical shifts of the
complexes 5a ,b and 6a ,b show considerable shielding
Me bond was observed with k ) 7.9 × 10-5 s-1
,
corresponding to ∆Gq ) 19.2(1) kcal/mol. After the
disappearance of the Pd-Me signal, insertion of ethyl-
ene into Pd-alkyl bonds was measured giving k )
2.4 × 10-4, ∆Gq ) 18.7(1) kcal/mol. For comparison,
typical migratory insertion barriers in (diimine)palla-
dium (methyl)(ethylene) complexes are ca. 17 kcal/mol.3a
Since ∆∆Gq ) 2 kcal corresponds to k2/k1 ) 30 (25 °C),
(8) Appleton, T. G.; Clark, H. C.; Manzer, L. E. Coord. Chem. Rev.
1973, 10, 335.
(6) (a) Appel, R.; Menzel, J .; Knoch, F.; Volz, P. Z. Anorg. Allg. Chem.
1986, 534, 100. (b) van der Sluis, M.; Beverwijk, V.; Termaten, A.;
Gavrilova, E.; Bickelhaupt, F.; Kooijman, H.; Veldman, N.; Spek, A.
L. Organometallics 1997, 16, 1144. (c) Ma¨rkl, G.; Kreitmeier, P.; No¨th,
H.; Polborn, K. Angew. Chem., Int. Ed. Engl. 1990, 29, 927. (d)
Yoshifuji, M.; Toyota, K.; Murayama, M.; Yoshimura, H.; Okamoto,
A.; Hirotsu, K.; Nagase, S. Chem. Lett. 1990, 2195. (e) van der Sluis,
M.; Bickelhaupt, F.; Veldman, N.; Kooijman, H.; Spek, A. L.; Eisfeld,
W.; Regitz, M. Chem. Ber. 1995, 128, 465. (f) Ito, S.; Toyota, K.;
Yoshifuji, M. Chem. Lett. 1995, 747. (g) Appel, R.; Winkhaus, V.; Knoch,
F. Chem. Ber. 1987, 120, 243.
(9) (a) Minami, T.; Okamoto, H.; Ikeda, S.; Tanaka, R.; Ozawa, F.;
Yoshifuji, M. Angew. Chem., Int. Ed. 2001, 40, 4501. (b) Toyota, K.;
Masaki, K.; Abe, T.; Yoshifuji, M. Chem. Lett. 1995, 221. (c) Chentit,
M.; Geoffroy, M.; Bernardinelli, G. Acta Crystallogr., Sect. C 1997, C53,
866. (d) Yamada, N.; Abe, K.; Toyota, K.; Yoshifuji, M. Org. Lett. 2002,
4, 569. (e) J ouaiti, A.; Geoffroy, M.; Bernardinelli, G. Chem. Commun.
1996, 437.
(10) Kawanami, H.; Toyota, K.; Yoshifuji, M. Chem. Lett. 1996, 533.
(11) (a) van Asselt, R.; Elsevier, C. J .; Smeets, W. J . J .; Spek, A. L.;
Benedix, R. Recl. Trav. Chim. Pays-Bas 1994, 113, 88. (b) Tempel, D.
J .; J ohnson, L. K.; Huff, R. L.; White, P. S.; Brookhart, M. J . Am. Chem.
Soc. 2000, 122, 6686.
(7) Ru¨lke, R. E.; Ernsting, J . M.; Spek, A. L.; Elsevier, C. J .; van
Leeuwen, P. W. N. M.; Vrieze, K. Inorg. Chem. 1993, 32, 5769.

Phosphinidine-Palladium Complexes
Organometallics, Vol. 21, No. 26, 2002 5937
Ta ble 2. Oligom er iza tion /P olym er iza tion of
Eth ylen e by 11a a n d 14 a t 26 °C, 400 p si in CH2Cl2
b
entry catalysta time, h g polymer TOF, h-1 Mn
branchingc
1
2
3
4
11a
11a
14
3
15
3
3.6
12.5
2.6
4300
3000
3100
2300
215d
60
40
119
119
180d
2300
2500e
14
8
5.2
a
b
0.01 mmol of catalyst in 100 mL of CH2Cl2 used. Mn
determined by 1H NMR spectroscopy (see Experimental Section
for details). c Branching determined by 1H NMR spectroscopy (see
d
Experimental Section for details). Butene, hexene, and octene
fraction partially lost during evaporation of solvent (GC analysis).
e GPC data: Mn ) 1900, Mw ) 2900, PDI ) 1.5.
turned to the investigation of phosphinidine-sulfide-
based catalysts. Initially, two ligands possessing bulky
substituents on sulfur were synthesized using phospha-
Petersen methodology developed by Yoshifuji et al.12 The
reaction of the potassium salt of tri-isopropylthiophenol
with bromoacetaldehyde diethyl acetal followed by
acidic hydrolysis afforded tri-isopropylphenylthioacetal-
dehyde 9. The aldehyde was then treated with Mes*P-
(Li)TBS to give a 100:8 mixture of phosphinidine
isomers. Crude phosphinidine was converted into the
corresponding complex 10a by treatment with (cod)-
PdMeCl. Chloride abstraction with Na(BArF)4 in the
presence of acetonitrile afforded the cationic complex
11a . In a similar way, complex 11b was obtained
starting from the known R-tert-butylthioacetaldehyde
(Scheme 3).13
F igu r e 2. ORTEP view of 6a . Selected interatomic dis-
tances (Å) and angles (deg): P(1)-Pd(1) ) 2.183(3), N(14)-
Pd(1) ) 2.166(8), Pd(1)-C(1) ) 2.052(10), Pd(1)-N(2) )
2.063(10), P(1)-C(6) ) 1.660(11), P(1)-C(15) ) 1.799(9),
N(14)-C(7) ) 1.287(15), N(2)-C(3) ) 1.107(17); C(6)-
P(1)-C(15) ) 113.7(5), C(7)-N(14)-C(33) ) 122.3(8).
Ta ble 1. Oligom er iza tion of Eth ylen e by 6a ,b a t
26 °C, 400 p si in CH2Cl2
b
entry
catalysta
time, h
mg oligomers
TOF, h-1
Mn
1
2
3
4
6a
6a
6b
6b
3
15
3
19
76
23
18
94
65
670
590
300
230
The reactions of ethylene with cationic complexes
11a ,b were initially studied by NMR spectroscopy using
20 equiv of olefin and 0.01 mmol of catalyst in CD2Cl2.
Under these conditions tert-butyl-substituted complex
11b produces a mixture of internal butenes. Interest-
ingly, the major component was cis-2-butene (2:1).
Gratifyingly, tri-isopropylphenyl-substituted catalyst
11a afforded ethylene oligomers in a relatively fast
reaction. In 3 h under 400 psi of ethylene, 0.01 mmol of
11a produced 3.6 g of oligomers (corresponding to 4300
TO/h) with Mn ) 215. In a 15 h run, TOF dropped to
3000 h-1, showing some catalyst decomposition (Table
2). Compared to diimine-Pd complexes, 11a displays
higher stability and produces lower molecular weight
material.
79c
270c
15
a
b
0.01 mmol of catalyst in 100 mL of CH2Cl2 used. Mn deter-
mined by 1H NMR spectroscopy (see Experimental Section for
details). c Butene, hexene, and octene fractions partially lost
during evaporation of solvent (GC analysis).
the difference in insertion barriers accounts for the
observed difference in TOF (Pd diimines: ca. 4500 TO/
h;3e 6b, 94 TO/h at RT).
In an effort to increase the molecular weight of the
oligomer/polymer produced, catalyst 14 was designed
and synthesized (Scheme 4). Geminal dimethyl groups
on the chelate backbone should impart a more restricted
conformation to the S-aryl group, possibly leading to
more efficient blocking of the axial sites on the metal
and potentially higher molecular weight material. The
synthesis started with the reaction of tri-isopropyl-
phenylsulfenyl chloride14 with the potassium enolate of
isobutyraldehyde to give the corresponding R-thioalde-
hyde 12.15 The conversion to the cationic palladium
complex 14 was carried out as in the case of 11.
Under 400 psi of ethylene, 14 produced highly
branched (119 br/1000 C) polyethylene with Mn ) 2300-
2500, PDI ) 1.5, consistent with a single-site catalyst
2. P alladiu m (II) Catalysts Con tain in g P h osph in i-
d in e-Su lfid e Liga n d s. Since the oligomerizations us-
ing phosphinidine-imine palladium complexes were
relatively slow, we decided to examine other chelating
ligand-palladium complexes incorporating the phos-
phinidine moiety. The use of phosphine-phosphinidine
palladium complex 8 (geometry around Pd arbitrary)
was not successful (butenes were produced at 1 atm
C2H4 in an NMR experiment). Modification of this
structure was problematic due to the instability of the
ligand and synthetic intermediates (high air and mois-
ture sensitivity, low crystallinity). As a consequence, we
(12) Yoshifuji, M.; Toyota, K.; Matsuda, I.; Niitsu, T.; Inamoto, N.
Tetrahedron Lett. 1985, 26, 1727.
(13) Kudzin, Z. H. Synthesis 1981, 643.
(14) Garratt, D. G.; Beaulieu, P. L. Can. J . Chem. 1980, 58, 2737.
(15) Groenewegen, P.; Kallenberg, H.; van der Gen, A. Tetrahedron
Lett. 1979, 20, 2817.

5938 Organometallics, Vol. 21, No. 26, 2002
Daugulis et al.
Sch em e 3
F igu r e 4. ORTEP view of 13. Selected interatomic dis-
tances (Å) and angles (deg): P(1)-Pd(1) ) 2.2071(8), S(1)-
Pd(1) ) 2.4277(8), Pd(1)-C(1) ) 2.047(3), Pd(1)-Cl(1) )
2.3475(8), P(1)-C(3) ) 1.659(3), S(1)-C(2) ) 1.891(3),
C(23)-C(37) ) 4.693(4), C(11)-S(1) ) 1.808(3); C(34)-
C(31)-P(1) ) 169.04(17).
F igu r e 3. ORTEP view of 10a . Selected interatomic
distances (Å) and torsion angles (deg): P(1)-Pd(1) )
2.1920(7), S(1)-Pd(1) ) 2.3965(7), Pd(1)-C(1) ) 2.046(3),
Pd(1)-Cl(1) ) 2.3496(7), P(1)-C(2) ) 1.652(3), S(1)-C(3)
) 1.826(3), C(34)-C(18) ) 5.130(4); P(1)-Pd(1)-S(1)-C(3)
13.96(15).
Ta ble 3. Com p a r ison of P olyeth ylen e Br a n ch in g
Obta in ed Usin g 14a a n d [((2,6-Me2C6H3)NdC(Me)-
C(Me)dN(2,6-Me2C6H3))P d (CH2)3C(O)OMe]BAr F 4
(15)16
Sch em e 4
catalyst Meb Et
Pr nBu sBu Am higher br/1000 Cc
14
39.0 29.7 5.2 16.7 6.7d 8.8
23.6
19.2
31.9
28.0
123
114
% Mee 31.7 24.1 4.2 13.6
7.2
15f
41.5 23.1 4.4
9.3 6.1d 4.6
8.2 4.0
% Mee 36.4 20.3 3.9
a
b
Reaction under the conditions of Table 2. Number of corre-
sponding branches per 1000 C. c Total number of methyl branches
d
per 1000 C. A sBu branch is counted as one Me and one Et
(Table 2). The observed TOF for a 3 h run was 3100
h-1, for an 8 h run 2300 TO/h. Remarkably, introduction
of the geminal dimethyl groups has increased the
molecular weight of the polymer more than 10 times.
To investigate the origin of this effect, single-crystal
X-ray structures were obtained for the complexes 10a
and 13 (Figures 3 and 4).
The geometries of these complexes were thought to
approximate the geometries of the active species in the
polymerization reaction. The CdP bond lengths (1.659-
(3) Å for 13 and 1.653 Å for 10a ) are typical for
phosphinidine-palladium complexes.6a,9 The Pd-P bonds
(2.2071(8) Å for 13, 2.1920(7) Å for 10a ) are slightly
longer than observed for 6a . As expected from the small
magnitude of CH3-31P coupling constants (see Experi-
mental Section for details), the methyl group is posi-
tioned cis to phosphinidine. The palladium-sulfur bond
is somewhat longer in 13 compared to 10a (2.4277(8)
vs 2.3965(7) Å). In 13, the five-membered chelate ring
is planar within 2 degrees; in 10a it adopts an envelope
conformation with the sulfur atom forming the flap of
the envelope (torsion angle P(1)-Pd(1)-S(1)-C(3) )
13.96(15)°). The C(34)-C(18) distance in 10a is 5.130-
(4) Å; in 13 the corresponding C(23)-C(37) distance is
branch. e Percent of the methyl groups in the given branch with
respect to total Me. f Data from ref 16, 500 psi ethylene pressure,
35 °C reaction temperature, chlorobenzene solvent.
4.693(4) Å, leading to a more efficient blocking of one
axial coordination site in the second case. Another
interesting feature of 13 is the deformation of the P-aryl
moiety, perhaps due to unfavorable steric interaction
of the 2-tert-butyl group with the isopropyl substituent.
The deformation results in a C(34)-C(31)-P(1) angle
of 169.04(17)° (reflecting the bending at C(31)). Ad-
ditionally in 13 the nonbonding interactions of the
geminal methyl groups with the isopropyl substituent
are expected to restrict the conformational mobility of
the S-aryl group, leading to more efficient shielding of
the lower axial coordination site on palladium.
Analysis of the nature of the branching using 13C
spectroscopy16 showed that the polymer is hyper-
branched, with methyl to amyl branches identified and
quantified (Table 3). The distribution of branches is
somewhat different from that observed for polyethylene
(16) Cotts, M. P.; Guan, Z.; McCord, E.; McLain, S. Macromolecules
2000, 19, 6945.

Phosphinidine-Palladium Complexes
Organometallics, Vol. 21, No. 26, 2002 5939
produced from palladium-diimine catalysts.16 The poly-
mer formed by 14 has somewhat fewer methyl branches
(39.0/1000 C compared to 41.5/1000 C) and substantially
more n-butyl branches (16.7 nBu/1000 C compared to
9.3 nBu/1000 C). The total number of branches calcu-
lated from 13C spectral analysis (123/1000 C) agrees
with the branching number obtained from the 1H
spectrum (119/1000 C).
3. P a lla d iu m (II) Ca ta lysts Con ta in in g Im in e-
Su lfid e Liga n d s. The replacement of an imine with a
phosphinidine moiety in these catalysts decreased the
molecular weight of ethylene polymerization products
(compare 1 and 6a ,b). As a consequence, an interesting
modification was the replacement of phosphinidine in
phosphinidine-sulfide ligands with an imine functional-
ity, leading to the structure 18. A few imine-sulfide
palladium and nickel catalysts have been described in
patent literature.17 The reaction of 12 with 2,6-di-
isopropylaniline afforded the corresponding imine. The
complexation with palladium was more difficult than
in the case of phosphinidines. Sulfide-imine ligand 16
did not displace cod from (cod)PdMeCl completely. To
obtain complete conversion to 17, azeotropic removal of
cyclooctadiene from the equilibrium mixture was neces-
sary. Conversion to 18 was carried out as in the case of
phosphinidines.
polymerization conditions than the corresponding imine
complexes; even after 15 h at RT phosphinidine-sulfide
catalyst 11a displays a turnover rate of 3000 TO/h,
while for a 3 h run the TOF was determined to be 4300
h-1. A new method of blocking axial sites on metal by
restricting the conformational mobility of the sulfide
ligand using gem-dimethyl substituents on the five-
membered chelate ring backbone has also been devel-
oped, resulting in a 10-fold molecular weight increase
of the polymer. Polyethylene obtained using phosphini-
dine-sulfide catalyst 14 is extremely highly branched
(119 br/1000 C).
Exp er im en ta l Section
Gen er a l Con sid er a tion s. All the operations related to
catalysts or phosphines were carried out under an argon
1
atmosphere using standard Schlenk techniques. The H, 31P,
and 13C spectra were recorded using Bruker 300 or 400 MHz
spectrometers and referenced against residual solvent peaks
(1H, 13C) or H3PO4 (31P). Flash chromatography was performed
using 60 Å silica gel (SAI). Room-temperature GPC measure-
ments were performed on a Waters Alliance HPLC separations
module equipped with Waters Styragel HR2, HR4, and HR5
columns in series and a Waters 2410 differential refractometer
RI (refractive index) detector relative to polystyrene standards.
Samples consisted of ∼1 mg of polymer in 1 mL of degassed
THF. Universal calibration was applied using Mark-Houwink
constants for polyethylene (k ) 4.34 × 10-4; R ) 0.724).
Elemental analyses were performed by Atlantic Microlab Inc.
of Norcross, GA. 13C NMR analysis of polymer obtained with
14 was carried out under the conditions reported by the
DuPont group.16
Ma ter ia ls. Anhydrous solvents were used in the reactions.
Solvents were distilled from drying agents or passed through
alumina columns under an argon or nitrogen atmosphere.
NMR solvents were vacuum transferred from P2O5 and de-
gassed by repeated freeze-pump-thaw cycles. The following
starting materials were made using literature procedures:
Mes*PCl2,18 Mes*PH2,18 (cod)PdMeCl,7 2,4,6-tri-isopropylthio-
phenol,19 R-tert-butylthioacetaldehyde,13 and 2,4,6-tri-isopro-
pylphenylsulfenyl chloride.14 NaB(ArF)4 was purchased from
Boulder Scientific.
In an NMR experiment (20 equiv of ethylene, 0.01
mmol of cat., CD2Cl2 solvent) catalyst 18 rapidly con-
sumed ethylene. A preparative run under 1 atm of
ethylene (0.01 mmol of cat., 100 mL of CH2Cl2) afforded
146 mg of polyethylene (Mn ) 2800) in 44 h. Under 400
psi ethylene, only a small amount (54 mg/3 h; 72 mg/15
h, 0.01 mmol 18) of polyethylene with Mn ) 1800 was
obtained. Since the 400 psi experiment afforded less
polyethylene than the 1 atm run, it is possible that
under high pressure of ethylene the ligand is displaced
from the palladium, resulting in the decomposition of
the catalyst (precipitation of palladium black was
observed).
An a lysis of P olym er Molecu la r Weigh t a n d Br a n ch in g
1
by H NMR Sp ectr oscop y. The following labels are used for
denoting different types of hydrogen signals in the polymer
spectrum (CDCl3 solvent): H1 (vinylidene end group, CdCH2,
br s, 4.7 ppm); H2 (1,2-disubstituted olefin, CHdCH, m, 5.3-
5.4 ppm); H3 (trisubstituted olefin CdCH, m, 5.18 ppm); H4
(R-olefin, H2CdCH, m, 5.85, 5.0, 4.9 ppm); H5 (alkyl methyl,
alk-CH3, m, 0.77-0.95 ppm); H6 (allylic methyl, CdC-CH3,
m, 1.6 ppm); H7 (alkyl methylene and methine, alk-CH and
alk-CH2, m, ca. 1.0-1.45 ppm); H8 (allylic methylene or
methine, CdC-CH2 and CdC-CH, m, 1.85-2.05 ppm). In the
following formulas Hn’s refer to integral values.
Nav ) (2/V)(A) + 2, where Nav ) average number of carbons
in polymer chain, V ) H1 + H2 + 2H3 + (2/3)H4, and A )
(H5 + H6 + H7 + H8 - H1 - H2 - 3H3 - (1/3)H4)/2
Su m m a r y
Several new cationic phosphinidine-imine, phosphini-
dine-sulfide, and imine-sulfide palladium(II) complexes
have been prepared. The complexes display moderate
to high activity (for palladium complexes) in the oligo-
merization and polymerization of ethylene. Phosphini-
dine-containing catalysts are more stable under the
Mn ) (Nav)14.01
Nbr ) (1000/Nav)(Y - X) where Nbr ) number of methyl
branches per 1000 C, Y ) ((H5 + H6)/3)(2/V), and X ) ((H1/2)
+ H2 + 2H3 + (H4/3))*(2/V). The formula is not exact since
the signal of the secondary homoallylic hydrogen overlaps with
the signal of H6.
(17) Al-Ahmad, S. WO 01/87996 A2, 2001. Several examples of
ethylene polymerization using cationic imine-sulfide Pd complexes are
described in this patent. Polyethylene with Mn of 200-700 was
obtained.
(18) Cowley, A. H.; Norman, N. C.; Pakulski, M. Inorg. Synth. 1990,
27, 235.
(19) Costanza, A. J .; Coleman, R. J .; Pierson, R. M.; Marvel, C. S.;
King, C. J . Polym. Sci. 1955, 17, 319.

5940 Organometallics, Vol. 21, No. 26, 2002
Daugulis et al.
Sp ectr a l Da ta for th e B(Ar F )4 Cou n ter ion . The following
1H and 13C spectroscopic assignments of the B(ArF)4 counterion
were invariant for different complexes and temperatures and
are not reported in the spectroscopic data for each of the
cationic complexes.
for 10 min at -78 °C followed by the addition of a solution of
propiophenone 2,6-diisopropylphenylimine (1.47 g, 5 mmol) in
THF (7 mL). The cooling bath was removed, and the reaction
mixture was stirred for 3 h at RT. The solution of lithium
azaenolate was added dropwise to a solution of 2,4,6-tri-tert-
butylphenyldichlorophosphine (1.77 g, 5 mmol; contained some
ArPBrCl) in THF (10 mL) at -78 °C. The reaction mixture
was warmed to RT and stirred for 1 h. Assay by 31P NMR
showed the presence of ArP(Cl)R (+99.8 ppm). The solvent was
evaporated under Ar, and dry DBU (1,8-diazabicyclo[5.4.0]-
undec-7-ene, 1.5 mL, 10 mmol, Aldrich) was added, followed
by dry CH3CN (7 mL). The mixture was heated in a sealed
Kontes flask at 90 °C for 3 h. Assay by 31P NMR showed the
presence of product and chloro (or bromo)phosphine in a 2.5:1
ratio (+304.0, +87.2 ppm) together with some unidentified
decomposition products. The solvent was evaporated and the
residue filtered through a 10 × 3.3 cm silica gel column in
toluene, collecting the red-yellow product band. After evapora-
tion the residue was recrystallized from CH3CN twice at -30
°C to give product as red-yellow crystals, 0.88 g (31.0%). Rf )
0.53 (1:1 toluene/hexane). 1H NMR (C6D6): 7.60 (s, 2H); 7.46-
7.39 (m, 2H); 7.07-6.85 (m, 6H); 3.12 (septet, 2H; J ) 6.8 Hz);
2.09 (d, 3H; J ) 12.5 Hz); 1.54 (s, 18H); 1.34 (s, 9H); 1.23 (d,
6H, J ) 6.8 Hz); 1.13 (d, 6H, J ) 6.8 Hz). 13C{1H, 31P} NMR
(CDCl3): 184.5; 169.0; 153.4; 150.5; 146.7; 137.7; 137.6; 135.4;
129.0; 128.6; 127.9; 127.4; 123.0; 122.4; 122.1; 38.1; 35.2; 32.7;
31.6; 28.8; 23.9; 22.0; 21.7. 31P{1H} NMR (C6D6): +303.0 ppm.
Anal. Calcd for C39H54NP: C 82.49, H 9.59, N 2.47. Found: C
82.28, H 9.73, N 2.43.
B[3,5-C6H3(CF 3)2]4- (B(Ar F )4). 1H NMR (CD2Cl2): 7.74 (br
s, 8H), 7.57 (s, 4H). 13C{1H} NMR (CD2Cl2): 162.2 (q, J C-B
37.4 Hz), 135.2, 129.3 (q, J C-F ) 31.3 Hz), 125.0 (q, J C-F
272.5 Hz), 117.9.
)
)
Gen er a l P olym er iza tion P r oced u r e. Polymerizations
were carried out in a mechanically stirred 300 mL Parr reactor
equipped with an electric heating mantle controlled by a
thermocouple in the reaction mixture. The reactor was charged
with toluene (100 mL) and heated for 1 h at 150 °C. After
cooling to RT the solvent was poured out and the reactor
heated under vacuum at 150 °C for 1 h. The reactor was filled
with Ar, cooled to RT, pressurized to 200 psi ethylene, and
vented three times. A solution of the catalyst in 100 mL of
CH2Cl2 was added to the reactor via cannula, the reactor
pressurized with ethylene to 400 psig, and the pressure
maintained at this value during the polymerization. After that
the reaction mixture was stirred for the appropriate time.
Observed exotherms were always less than 2 °C, and the
polymerizations were run at 26 °C. After venting the reaction
mixture was evaporated and the distillate checked for oligo-
mers by GC.
P r op iop h en on e 2,6-Di-isop r op ylp h en ylim in e, 3a . 2,6-
Diisopropylaniline (3.8 mL, 20 mmol, Aldrich) was mixed with
propiophenone (2.7 mL, 20 mmol, Aldrich) and p-TsOH (0.4
g, 2.1 mmol, Aldrich). The resulting mixture was heated at
205 °C for 1.5 h under a weak stream of Ar to remove formed
H2O. After cooling to RT the reaction mixture was poured into
hexanes (50 mL) and filtered, and the precipitate was washed
with additional hexanes (2 × 20 mL) followed by the evapora-
tion of the filtrate and distillation of the residue. After the
initial fraction of starting materials (80-110 °C/0.5 mm) the
product was collected as a yellow oil, bp 110-125 °C/0.5 mm.
Crystallization from methanol at -30 °C afforded the product
as yellow crystals (4.3 g, 73.3%). 1H NMR (CDCl3): 7.99-7.91
(m, 2H); 7.54-7.44 (m, 3H); 7.20-7.13 (m, 2H); 7.12-7.04 (m,
1H); 2.78 (septet, 2H; J ) 6.9 Hz); 2.53 (q, 2 H; J ) 7.7 Hz);
1.21 (d, 6 H; J ) 6.9 Hz); 1.16 (d, 6 H; J ) 6.9 Hz); 0.99 (t, 3
H; J ) 7.7 Hz). 13C{1H} NMR (CDCl3): 169.9, 146.6, 138.2,
136.1, 130.3, 128.7, 127.9, 123.4, 123.0, 28.4, 24.3, 23.7, 22.7,
11.4. Anal. Calcd for C21H27N: C 85.95, H 9.27, N 4.77.
Found: C 86.05, H 9.32, N 4.79.
MesNdC(P h )C(Me)dP Mes*, 4b. nBuLi (2.3 mL of a 1.6
M solution in hexanes, 3.7 mmol, Aldrich) was added to a
solution of diisopropylamine (0.54 mL, 3.85 mmol, Aldrich) in
THF (10 mL) at -78 °C. The solution was stirred for 10 min
at -78 °C followed by the addition of a solution of propiophe-
none 2,4,6-trimethylphenylimine (0.88 g, 3.51 mmol) in THF
(15 mL). The cooling bath was removed, and the reaction
mixture was stirred for 3 h at RT. The solution of lithium
azaenolate was added dropwise to a solution of 2,4,6-tri-tert-
butylphenyldichlorophosphine (1.24 g, 3.57 mmol; contained
some ArPBrCl) in THF (10 mL) at -78 °C. The reaction
mixture was warmed to RT and stirred for 1 h. Assay by 31P
NMR showed the presence of ArP(Cl)R (+90.3 ppm). Dry DBU
(1.1 mL, 7.36 mmol, Aldrich) was added. After 2 h, assay by
31P NMR showed no reaction. The solvent was evaporated
under vacuum, and dry CH2Cl2 (10 mL) and dry CH3CN (10
mL) were added. The mixture was stirred at RT for 15 h 30
min. Assay by 31P NMR (crude reaction mixture) showed the
presence of product isomers in a 100:4 ratio (+306.7; +279.3
ppm). The solvent was evaporated and the residue filtered
through a 16 × 3.3 cm silica gel plug in CH2Cl2, collecting 100
mL. After evaporation the residue was recrystallized from dry
CH3CN at -30 °C to give product as yellow crystals, 1.04 g
(57.0%). 1H NMR (CDCl3): 7.46 (s, 2H); 7.28-7.12 (m, 5H);
6.64 (s, 2H); 2.13 (s, 3H); 1.96 (s, 6H); 1.70 (d, 3H; J ) 12.4
Hz); 1.47 (s, 18H); 1.36 (s, 9H). 13C{1H, 31P} NMR (CDCl3):
183.9; 170.7; 153.3; 150.6; 146.6; 138.4; 137.6; 131.5; 128.6;
128.4; 128.3; 127.4; 125.1; 122.1; 38.1; 35.2; 32.7; 31.6; 21.6;
20.9; 18.6. 31P{1H} NMR (CDCl3): +307.0 ppm. Anal. Calcd
for C36H48NP: C 82.24, H 9.20, N 2.66. Found: C 82.11, H
9.32, N 2.67.
P r op iop h en on e 2,4,6-Tr im eth ylp h en ylim in e, 3b. 2,4,6-
Trimethylaniline (11.5 mL, 82 mmol, Aldrich) was mixed with
propiophenone (10 mL, 74.5 mmol, Aldrich) and p-TsOH (1.4
g, 7.3 mmol, Aldrich). The resulting mixture was heated for 2
h at 200 °C under a weak stream of Ar to remove formed H2O.
After cooling to RT the reaction mixture was poured into
hexanes (100 mL) and filtered, and the precipitate washed
with additional hexanes (2 × 100 mL) followed by the evapora-
tion of the filtrate. The residue was filtered through a 9 × 4.1
cm plug of silica gel in 10:1 hexanes/ether (300 mL collected).
After evaporation of the solvent the unreacted starting materi-
als were distilled off under vacuum (45-50 °C/0.4 mm). The
residue was crystallized from methanol at -30 °C. Product
was isolated as large orange-yellow crystals, 4.8 g (25.6%). 1H
NMR (CDCl3): 8.00-7.94 (m, 2H); 7.51-7.45 (m, 3H); 6.89 (s,
2H); 2.50 (q, 2H; J ) 7.7 Hz); 2.31 (s, 3H); 2.04 (s, 6H); 0.98 (t,
3H; J ) 7.7 Hz). 13C{1H} NMR (CDCl3): 170.8, 146.4, 138.2,
131.9, 130.3, 128.7, 128.6, 127.7, 125.6, 23.9, 20.9, 18.2, 11.6.
Anal. Calcd for C18H21N: C 86.00, H 8.42, N 5.57. Found: C
85.79, H 8.41, N 5.56.
[(2,6-(i-P r )2C6H 3)NdC(P h )C(Me)dP Mes*]P d MeCl, 5a .
(Cod)PdMeCl (0.047 g, 0.176 mmol) was mixed with 4a (0.10
g, 0.176 mmol) and CH2Cl2 (3 mL). The yellowish solution was
stirred for 14 h at RT. After evaporation the residue was
triturated with hexanes (3 mL). The hexanes were evaporated,
and the residue was dried under vacuum to give 5a as a
1
reddish solid (0.109 g, 85.4%). H NMR (CDCl3): 7.62 (d, 2H;
(2,6-(i-P r )2C6H3)NdC(P h )C(Me)dP Mes*, 4a . nBuLi (3.3
mL of a 1.6 M solution in hexanes, 5.25 mmol, Aldrich) was
added to a solution of diisopropylamine (0.77 mL, 5.5 mmol,
Aldrich) in THF (5 mL) at -78 °C. The solution was stirred
J ) 3.3 Hz); 7.22-7.14 (m, 3H); 7.09-6.94 (m 3H); 6.92-6.83
(m, 2H); 3.00 (septet, 2H; J ) 6.8 Hz); 1.69 (d, 18H; J ) 0.7
Hz); 1.47 (d, 6H; J ) 6.8 Hz); 1.36 (s, 9H); 1.26 (Pd-Me; d, 3H;

Phosphinidine-Palladium Complexes
Organometallics, Vol. 21, No. 26, 2002 5941
J ) 4.2 Hz); 1.18 (d, 3H; J ) 26.0 Hz); 1.00 (d, 6H; J ) 6.8
Hz). 31P{1H} NMR (CDCl3): +268.3 ppm. Anal. Calcd for
Sp ectr a l Da ta for 7. 31P{1H} NMR (CD2Cl2, 233 K):
+255.6 ppm. H NMR (CD2Cl2, 243 K): 7.65 (d, 2H; J ) 3.7
1
C
40H57ClNPPd: C 66.29, H 7.93, N 1.93. Found: C 66.20, H
Hz); 7.35-7.21 (m, 3H); 6.94-6.87 (m, 2H); 6.80 (s, 2H); 2.17
(s, 3H); 2.15 (s, 6H); 1.60 (s, 18H); 1.35 (d, 3H; J ) 29.0 Hz);
1.32 (s, 9H); 0.95 (Pd-Me; d, 3H; J ) 3.7 Hz). Complexed
ethylene exchanges with excess free ethylene fast even at 193
K, resulting in coalescence of NMR signals (5.37 ppm at 243
K and 22 equiv of ethylene).
8.01, N 1.91.
[MesNdC(P h )C(Me)dP Mes*]P d MeCl, 5b. The synthesis
was performed as in the case of 5a , using 4b (0.200 g, 0.38
mmol) and (cod)PdMeCl (0.101 g, 0.38 mmol) in CH2Cl2 (5 mL).
The product was isolated as a reddish solid (0.23 g, 88.7%).
1H NMR (CD2Cl2): 7.65 (d, 2H; J ) 3.3 Hz); 7.27-7.17 (m,
3H); 6.99-6.90 (m, 2H); 6.69 (s, 2H); 2.19 (s, 6H); 2.18 (s, 3H);
1.69 (d, 18H; J ) 1.1 Hz); 1.37 (s, 9H); 1.12 (Pd-Me; d, 3H;
J ) 4.4 Hz); 1.11 (d, 3H; J ) 26.3 Hz). 13C{1H} (CD2Cl2) 176.8
(d, J C-P ) 11.1 Hz); 163.5 (d, J C-P ) 45.8 Hz); 157.0; 155.4 (d,
J C-P ) 2.4 Hz); 144.8 (d, J C-P ) 3.3 Hz); 135.6 (d, J C-P ) 10.9
Hz); 134.8; 129.6; 129.5 (d, J C-P ) 4.1 Hz); 128.6; 128.1; 126.3;
124.4 (d, J C-P ) 8.0 Hz); 121.0 (d, J C-P ) 3.5 Hz); 39.4; 35.9;
33.7 (d, J C-P ) 1.4 Hz); 31.1; 22.1 (d, J C-P ) 11.7 Hz); 21.1;
19.4; 2.0 (Pd-Me; d, J C-P ) 2.9 Hz). 31P{1H} NMR (CD2Cl2):
+267.3 ppm. Anal. Calcd for C37H51ClNPPd: C 65.09, H 7.53,
N 2.05. Found: C 64.96, H 7.53, N 2.08.
[((2,6-(i-P r )2C6H 3)NdC(P h )C(Me)dP Mes*)P d (NCMe)-
Me]+B(Ar F )4-, 6a . To the mixture of 5a (prepared from 0.176
mmol of 4a , 0.176 mmol of (cod)PdMeCl) and NaB(ArF)4 (0.156
g, 0.176 mmol) were added dry acetonitrile (1 mL) and CH2-
Cl2 (3 mL). The mixture was stirred for 1 h at RT, cannula
filtered to remove NaCl, evaporated, and coevaporated with
hexanes (3 mL). The product was obtained as a reddish solid
(0.270 g, 96.3%). X-ray quality crystals were obtained by
crystallization from warm toluene. 1H NMR (CD2Cl2): 7.70 (d,
2H; J ) 4.0 Hz); 7.36-7.28 (m, 3H); 7.18-7.08 (m, 3H); 6.98-
6.93 (m, 2H); 2.94 (septet, 2H; J ) 6.8 Hz); 1.75 (s, 3H); 1.67
(d, 18 H; J ) 1.3 Hz); 1.4 (d, 6H; J ) 6.8 Hz); 1.37 (s, 9H);
1.36 (d, 3H; J ) 29.3 Hz); 1.09 (d, 6H; J ) 6.8 Hz); 1.03 (Pd-
Me; d, 3H; J ) 2.6 Hz). 31P{1H} NMR (CD2Cl2): +267.4 ppm.
Anal. Calcd for C74H72BF24N2PPd: C 55.77, H 4.55, N 1.76.
(2,4,6-Tr i-isop r op ylp h en ylth io)a ceta ld eh yd e, 9. To a
solution of 2,4,6-tri-isopropylthiophenol (8.0 g, 33.9 mmol) in
THF (130 mL) was added KHMDS (74.5 mL of a 0.5 M toluene
solution, 37.3 mmol, Aldrich) at 0 °C and the resulting mixture
stirred for 30 min at 0 °C. Bromoacetaldehyde diethylacetal
(5.6 mL, 37.3 mmol, Aldrich) was added dropwise to the
solution of the potassium thiolate at 0 °C. The ice bath was
removed and the reaction mixture stirred for 4 h at RT. After
that, it was poured into H2O (300 mL) and extracted with
diethyl ether (3 × 200 mL). Extracts were then dried (MgSO4),
filtered, and evaporated (aspirator). The crude reaction mix-
ture was refluxed with 2% aqueous HCl (60 mL) and acetone
(100 mL) for 2 h. The reaction mixture was poured into
saturated aqueous sodium bicarbonate solution and extracted
with diethyl ether (2 × 200 mL), and the extracts were dried
(MgSO4), filtered, and evaporated. Distillation of the product
gave a clear liquid, bp 108-113 °C/0.5 mm, 5.79 g (61.4%).
The compound slowly decomposes at RT and needs to be stored
1
in the freezer. H NMR (C6D6): 9.57 (t, 1H; J ) 3.4 Hz); 7.00
(s, 2H); 3.96 (septet, 2H; J ) 7.0 Hz); 2.81 (d, 2H; J ) 3.4 Hz);
2.70 (septet, 1H; J ) 7.0 Hz); 1.21 (d, 12H; J ) 7.0 Hz); 1.13
(d, 6H; J ) 7.0 Hz). 13C{1H} NMR (CDCl3): 193.3; 154.0; 151.1;
127.2; 122.8; 47.5; 35.0; 32.3; 24.9; 24.4. Anal. Calcd for C17H26
OS: C 73.32, H 9.41. Found: C 73.38, H 9.50.
-
Mes*P (Li)TBS.6b nBuLi (2.6 mL of a 1.6 M solution in
hexanes, 4.2 mmol, Aldrich) was added to a solution of 2,4,6-
tri-tert-butylphenylphosphine (1.11 g, 4 mmol) in THF (30 mL)
at -78 °C. The yellow suspension was stirred at -78 °C for
10 min, warmed to RT, and stirred for additional 15 min. A
dark red solution was formed. Next, a solution of TBSCl (tert-
butyldimethylsilyl chloride, 0.63 g, 4.2 mmol, Aldrich) in THF
(10 mL) was added to ArPHLi over 10 min at 0 °C. The
resulting yellowish solution was stirred at 0 °C for 20 min,
warmed to RT, and stirred for 30 min. Assay by 31P NMR
showed clean formation of ArPHTBS (-135.5 ppm). After
cooling to -78 °C additional nBuLi (2.6 mL of a 1.6 M solution
in hexanes, 4.2 mmol, Aldrich) was added, and the solution
was immediately warmed to RT to give a reddish solution of
ArP(Li)TBS that was used in the phosphinidine synthesis.
[(2,4,6-(i-P r )3C6H2)SCH2CHdP Mes*]P d MeCl, 10a . A so-
lution of (2,4,6-tri-isopropylphenylthio)acetaldehyde (0.835 g,
3.0 mmol) in THF (10 mL) was dropwise added to a solution
of ArP(TBS)Li prepared as above (3.15 mmol scale) at -78 °C.
The reaction color changed from red to yellow at the end of
the reaction. After stirring for 30 min at -78 °C the reaction
was warmed to RT and stirred for 1 h. TMSCl (0.3 mL) was
then added to quench TBSOLi. Assay by 31P NMR showed the
presence of phosphinidine isomers in the ratio of 100:8 (+262.5;
+254.1 ppm). The solution was evaporated, CH2Cl2 (10 mL)
was added followed by (cod)PdMeCl (0.670 g, 2.53 mmol), and
the reaction mixture was stirred for 12 h at RT. The solution
was evaporated and the residue purified by flash chromatog-
raphy on silica gel (7.5 × 3.7 cm). Initially cod, ArPH2, and a
minor phosphinidine diastereomer were eluted with hexanes
(300 mL). After that, a dark red impurity was eluted with
toluene (475 mL). Then, product was eluted with CH2Cl2 (400
mL). Fractions containing 10a were evaporated and crystal-
lized from acetonitrile (50 mL) at -30 °C. Product was
obtained as a light yellow, somewhat light sensitive solid, 0.60
g (28.7%). 1H NMR (CD2Cl2): 7.61 (d, 2H; J ) 3.5 Hz); 7.37
(dt, 1H; J ) 19.8, 4.2 Hz); 7.14 (s, 2H); 3.96 (septet, 2H; J )
6.8 Hz); 3.56 (dd, 2H; J ) 40.4; 4.2 Hz); 2.94 (septet, 1H: J )
6.9 Hz); 1.67 (s, 18H); 1.39 (d, 6H; J ) 6.8 Hz); 1.36 (s, 9H);
Found: C 55.48, H 4.42, N 1.73.
[(MesNdC(P h )C(Me)dP Mes*)P d (NCMe)Me]+B(Ar F )4
-
,
6b. The synthesis was performed as in the case of 6a , using
4b (0.100 g, 0.19 mmol), (cod)PdMeCl (0.050 g, 0.19 mmol),
and NaB(ArF)4 (0.169 g, 0.19 mmol). Product was obtained as
1
a reddish powder, 0.292 g (100%). H NMR (CD2Cl2): 7.69 (d,
2H; J ) 3.9 Hz); 7.37-7.23 (m, 3H); 7.00-6.94 (m, 2H); 6.80
(s, 2H); 2.22 (s, 6H); 2.19 (s, 3H); 1.74 (s, 3H); 1.66 (d, 18H;
J ) 1.3 Hz); 1.37 (s, 9H); 1.30 (d, 3H; J ) 29.4 Hz); 1.02 (Pd-
Me; d, 3H; J ) 2.6 Hz). 13C{1H} NMR (CD2Cl2): 177.8 (d,
J C-P ) 8.0 Hz); 167.5 (d, J C-P ) 54.4 Hz); 157.5 (d, J C-P ) 1.8
Hz); 157.1 (d, J C-P ) 2.9 Hz); 143.9 (d, J C-P ) 3.7 Hz); 136.6;
133.6 (d, J C-P ) 10.7 Hz); 130.9; 129.2; 129.1 (d, J C-P ) 2.4
Hz); 126.4; 125.1 (d, J C-P ) 9.3 Hz); 120.5; 117.5 (d, J C-P
)
15.3 Hz); 39.5 (d, J C-P ) 1.7 Hz); 36.0; 33.9; 31.2; 22.6 (d,
J C-P ) 11.3 Hz); 20.9; 19.0; 3.8 (Pd-Me; d, J C-P ) 2.7 Hz); 2.0.
One aromatic carbon is unaccounted for. 31P{1H} NMR (CD2-
Cl2): +266.0 ppm. Anal. Calcd for C71H66BF24N2PPd: C 54.96,
H 4.29, N 1.80. Found: C 55.32, H 4.63, N 1.78.
Gen er a t ion of [(MesNdC(P h )C(Me)dP Mes*)P d (et h -
ylen e)Me]+B(Ar F )4-, 7. Mea su r em en t of Eth ylen e In ser -
tion Ba r r ier . Solid 5b (0.0068 g, 0.01 mmol) was mixed with
NaB(ArF)4 (0.012 g, 0.014 mmol) in a Teflon-lined screw-cap
NMR tube. After cooling to -78 °C ethylene (1 mL, 0.045
mmol) was added, followed by CD2Cl2 (0.7 mL) and more
ethylene (4 mL, 0.18 mmol). The NMR tube was placed in an
NMR probe at 250 K, and the disappearance of the methyl
peak (0.95 ppm) of the formed methyl ethylene complex was
observed vs time, affording k ) 7.9 × 10-5 s-1, corresponding
to ∆Gq ) 19.2(1) kcal/mol. After the disappearance of the
methyl peak, additional ethylene (5 mL, 0.22 mmol) was added
and the disappearance of the ethylene peak was measured
with respect to time, affording k ) 2.4 × 10-4 s-1, ∆Gq
)
18.7(1) kcal/mol. The error was derived from the error in the
rate constant, which in turn was obtained by the least-squares
fit of the kinetic data.

5942 Organometallics, Vol. 21, No. 26, 2002
Daugulis et al.
1.31 (d, 6H; J ) 6.8 Hz); 1.29 (d, 6H; J ) 6.9 Hz); 1.15 (Pd-
Me; d, 3H; J ) 4.1 Hz). 31P{1H} NMR (CD2Cl2): +237.6 ppm.
Anal. Calcd for C36H58ClPPdS: C 62.14, H 8.40. Found: C
62.17, H 8.45.
extracted with diethyl ether (2 × 30 mL), and the extracts were
dried (MgSO4), filtered, and evaporated. The residue was
purified by flash chromatography on silica gel (13 × 4.3 cm)
in 1:5 toluene/hexane followed by 1:4. Fractions containing the
product were evaporated to give a light yellow oil that slowly
crystallized, m ) 2.034 g (68.5%). Rf ) 0.33 (1:3 toluene/
hexane). 1H NMR (CDCl3): 9.34 (s, 1H); 7.00 (s, 2H); 3.85
(septet, 2H; J ) 6.9 Hz); 2.86 (septet, 1H; J ) 6.9 Hz); 1.29 (s,
6H); 1.24 (d, 6H; J ) 6.9 Hz); 1.18 (unresolved br d, 12H). 13C-
{1H} NMR (CDCl3, 333 K): 195.8; 155.2; 151.1; 123.7; 122.1;
55.7; 34.5; 32.3; 24.5; 24.0; 21.7. Anal. Calcd for C19H30OS: C
74.45, H 9.87. Found: C 74.52, H 9.98.
[((2,4,6-(i-P r )3C6H2)SCH2CHdP Mes*)P d (NCMe)Me]+B-
(Ar F )4-, 11a . To the mixture of 10a (0.129 g, 0.186 mmol) and
NaB(ArF)4 (0.165 g, 0.186 mmol) were added dry acetonitrile
(1 mL) and CH2Cl2 (3 mL). The mixture was stirred for 17 h
at RT, cannula filtered to remove NaCl, evaporated, and
coevaporated with hexanes (3 mL). The product was obtained
as a reddish solid (0.250 g, 85.9%). 1H NMR (CD2Cl2): 7.65
(d, 2H; J ) 4.2 Hz); 7.48 (dt, 1H; J ) 19.4, 4.2 Hz); 7.19 (s,
2H); 3.88 (septet, 2H; J ) 6.8 Hz); 3.76 (dd, 2H; J ) 42.4; 4.2
Hz); 2.95 (septet, 1H; J ) 6.9 Hz); 2.00 (s, 3H); 1.64 (s, 18H);
1.36 (s, 9H); 1.33 (br d, 12H; J ) 6.8 Hz); 1.26 (d, 6H; J ) 6.9
Hz), 1.19 (Pd-Me; d, 3H; J ) 2.4 Hz). 31P{1H} NMR (CD2Cl2):
+231.0 ppm. Anal. Calcd for C70H74BF24NPPdS: C 53.70, H
4.76, N 0.89. Found: C 53.88, H 4.88, N 0.80.
[(2,4,6-(i-P r )3C6H2)SCMe2CHdP Mes*]P d MeCl, 13. A so-
lution of 2-methyl-2-(2,4,6-tri-isopropylphenylthio)propanal
(0.307 g, 1.0 mmol) in THF (5 mL) was added dropwise to a
solution of ArP(TBS)Li prepared from 2,4,6-tri-tert-butylphen-
ylphosphine (1.05 mmol) at -78 °C. The reaction color changed
from red to light yellow at the end of the reaction. After stirring
for 30 min at -78 °C the reaction was warmed to RT. Assay
by 31P NMR showed the presence of phosphinidine (+249.5
ppm). TMSCl (0.2 mL) was added to quench TBSOLi, the
solution was evaporated, and the residue was coevaporated
with hexanes (10 mL). A solution of (cod)PdMeCl (0.265 g, 1.0
mmol) in CH2Cl2 (5 mL) was added to the crude phosphinidine
and the mixture stirred at RT for 10 h. The color gradually
changed from colorless to red-brown. After evaporation, the
residue was dissolved in hexanes and purified on a 4 × 2.3
cm silica gel column, eluting first with hexanes (80 mL) to
remove cod and ArPH2, then with CH2Cl2 (60 mL) to obtain
the product. After evaporation the residue was triturated with
hexanes (-30 °C) to give 0.63 g (87.1%) of 13 as yellow crystals.
X-ray quality crystals were obtained by crystallization from
t-Bu SCH2CHdP Mes*. A solution of (tert-butylthio)acetal-
dehyde (0.32 g, 2.4 mmol) in THF (7 mL) was added dropwise
to a solution of 2,4,6-tri-tert-butylphenylP(TBS)Li prepared
from 2,4,6-tri-tert-butylphenylphosphine (2 mmol) at -78 °C.
The reaction color changed from red to yellow at the end of
the reaction. After stirring for 30 min at -78 °C the reaction
was warmed to RT. Assay by 31P NMR showed the presence
of phosphinidine isomers in the ratio of 100:11 (+258.9; +252.8
ppm). TMSCl (0.3 mL) was added to quench TBSOLi, the
solution was evaporated, and the residue was purified by flash
chromatography on silica gel (14.5 × 3.3 cm) in 15:1 hexane/
toluene followed by 10:1. Fractions containing the major isomer
were evaporated to give colorless oil that slowly crystallized.
After recrystallization from dry acetonitrile at -30 °C colorless
crystals (0.303 g, 38.6%) were obtained. Major diastereomer
(trans) Rf ) 0.16 (15:1 hexane/toluene). Minor diastereomer
1
acetonitrile at -30 °C. H NMR (CDCl3): 7.54 (d, 2H; J ) 3.4
Hz); 7.18 (d, J ) 18.9 Hz); 7.05 (s, 2H); 4.09 (septet, 2H; J )
6.8 Hz); 2.86 (septet, 1H; J ) 6.9 Hz); 1.66 (s, 18H); 1.39 (d,
6H; J ) 6.8 Hz); 1.32 (s, 15H; accidental overlap of t-Bu and
gem-dimethyl); 1.29 (d, 6H; J ) 6.8 Hz); 1.24 (Pd-Me; d, 3H;
J ) 4.7 Hz); 1.23 (d, 6H; J ) 6.9 Hz). 13C{1H} (CDCl3) 173.3
(d, J C-P ) 55.3 Hz); 156.0 (d, J C-P ) 3.2 Hz); 154.1; 153.7 (d,
J C-P ) 2.6 Hz); 152.0; 123.9 (d, J C-P ) 8.9 Hz); 123.6 (d,
1
(cis) Rf ) 0.25. The ligand is somewhat sensitive to water. H
NMR (major diastereomer, CD2Cl2): 7.39 (d, 2H; J ) 0.9 Hz);
7.28 (dt, 2H; J ) 24.7, 9.2 Hz); 3.67 (dd, 2H; J ) 20.9, 9.2 Hz);
1.49 (s, 18H); 1.31 (s, 9H); 1.30 (s, 9H). 31P{1H} NMR (CD2-
Cl2): +258.0 ppm. Anal. Calcd for C24H41PS: C 73.41, H 10.51.
Found: C 73.40, H 10.69.
J C-P ) 8.7 Hz); 123.0; 122.5 (d, J C-P ) 2.5 Hz); 58.0 (d, J C-P
)
[t-Bu SCH2CHdP Mes*]P d MeCl, 10b. The synthesis was
performed as in the case of 5a , using t-BuSCH2CHdPMes*
(0.05 g, 0.127 mmol) and (cod)PdMeCl (0.034 g, 0.127 mmol).
Product was obtained as an off-white solid, 0.058 g (83.1%).
1H NMR (CDCl3): 7.54 (d, 2H; J ) 3.4 Hz); 7.45 (dt, 1H; J )
19.0, 4.2 Hz), 3.29 (dd, 2H; J ) 40.0, 4.2 Hz); 1.62 (s, 9H);
1.58 (s, 18H); 1.33 (s, 9H); 1.23 (Pd-Me; d, 3H; J ) 3.7 Hz).
7.1 Hz); 39.4 (d, J C-P ) 1.3 Hz); 35.5; 34.4; 34.2 (d, J C-P ) 2.3
Hz); 32.6; 31.3; 29.9 (d, J C-P ) 16.0 Hz); 26.5; 24.0; 23.6; 10.8
(Pd-Me; d, J C-P ) 5.7 Hz). 31P{1H} NMR (C6D6): +219.1 ppm.
Anal. Calcd for C38H62ClPPdS: C 63.05, H 8.63. Found: C
62.94, H 8.64.
[(2,4,6-(i-P r )3C6H 2)SMe2CH dP Mes*)P d (NCMe)Me]+B-
(Ar F )4-, 14. The synthesis was performed as in the case of 6a ,
using 13 (0.160 g, 0.22 mmol) and NaB(ArF)4 (0.200 g, 0.22
mmol). Product was obtained as a reddish foam, 0.320 g
31P{1H} NMR (CDCl3): +236.9 ppm. Anal. Calcd for C25H44
ClPPdS: C 54.64, H 8.07. Found: C 54.88, H 8.10.
-
[(t-Bu SCH2CHdP Mes*)P d(NCMe)Me]+B(Ar F)4-, 11b. The
synthesis was performed as in the case of 6a , using t-BuSCH2-
CHdPMes* (0.100 g, 0.255 mmol), (cod)PdMeCl (0.068 g, 0.255
mmol), and NaB(ArF)4 (0.226 g, 0.255 mmol). Product was
obtained as a reddish foam, 0.290 g (86.7%). 1H NMR (CD2-
Cl2): 7.62 (d, 2H; J ) 4.1 Hz); 7.59 (dt, 1H; J ) 18.3, 4.2 Hz);
3.44 (dd, J ) 42.1, 4.2 Hz); 2.37 (s, 3H); 1.56 (d, 18H; J ) 0.9
Hz); 1.54 (s, 9H); 1.34 (s, 9H); 1.14 (Pd-Me; d, 3H; J ) 2.3
Hz). 31P{1H} NMR (CD2Cl2): +229.3 ppm. Anal. Calcd for
1
(91.3%). H NMR (CD2Cl2): 7.66 (d, 2H; J ) 4.2 Hz); 7.33 (d,
1H; J ) 18.5 Hz); 7.23 (s, 2H); 4.01 (septet, 2H; J ) 6.8 Hz);
2.96 (septet, 1H; J ) 6.9 Hz); 2.04 (s, 3H); 1.68 (d, 18H; J )
0.8 Hz); 1.44 (d, 6H; J ) 2.2 Hz); 1.38 (d, 6H; J ) 6.8 Hz);
1.37 (s, 9H); 1.31 (d, 6H; J ) 6.8 Hz); 1.28 (d, 6H; J ) 6.9 Hz);
1.19 (Pd-Me; d, 3H; J ) 2.6 Hz). 31P{1H} NMR (CD2Cl2):
+210.0 ppm (s). 13C{1H} (CD2Cl2): 176.9 (d, J C-P ) 62.9 Hz);
156.8 (d, J C-P ) 3.8 Hz); 156.0 (d, J C-P ) 3.1 Hz); 154.5; 154.3;
124.8 (d, J C-P ) 10.0 Hz); 124.2; 121.5 (d, J C-P ) 2.0 Hz); 121.0
(d, J C-P ) 20.3 Hz); 120.0; 60.1 (d, J C-P ) 3.3 Hz); 39.9 (d,
J C-P ) 1.7 Hz); 36.0; 34.9; 34.5 (d, J C-P ) 1.7 Hz); 33.3; 31.2;
29.8 (d, J C-P ) 16.5 Hz); 26.6; 23.9; 23.6; 12.2 (Pd-Me; d,
J C-P ) 5.6 Hz), 3.1. 31P{1H} NMR (CD2Cl2): +210.0 ppm. Anal.
Calcd for C72H77BF24NPPdS: C 54.29, H 4.87, N 0.88. Found:
C 54.52, H 4.92, N 0.85.
C
59H59BF24NPPdS: C 49.96, H 4.19, N 0.99. Found: C 50.28,
H 4.23, N 0.99.
2-Meth yl-2-(2,4,6-tr i-isopr opylph en ylth io)pr opan al, 12.
To a suspension of KH (383 mg, 9.5 mmol, Aldrich; washed
with hexanes to remove oil and dried in a vacuum) in THF
(10 mL) was added dropwise isobutyric aldehyde (0.79 mL, 8.7
mmol, Aldrich) in THF (3 mL). The suspension was stirred
for 25 min at RT under Ar (evolution of H2!). A solution of 2,4,6-
tri-isopropylphenylsulfenyl chloride (2.35 g, 8.7 mmol) in THF
(10 mL) was then added in one portion. The color immediately
changed from red to yellow. The solution was stirred at RT
for 10 min, and water (20 mL) was added to the reaction
mixture under Ar (caution: H2 evolution!). The solution was
(2,4,6-(i-P r )3C6H2)SCMe2CHdN(2,6-(i-P r )2C6H3), 16. To
a solution of 2-methyl-2-(2,4,6-tri-isopropylphenylthio)propanal
(0.556 g, 2.0 mmol) in methanol (4 mL) was added formic acid
(4 drops) and 2,6-diisopropylaniline (0.76 mL, 4.0 mmol,
Aldrich). The reaction was stirred for 20 h at RT. TLC assay
showed that reaction was completed at that time. After

Phosphinidine-Palladium Complexes
Organometallics, Vol. 21, No. 26, 2002 5943
Ta ble 4. Cr ysta llogr a p h ic Da ta Collection P a r a m eter s for 4a , 6a , 10a , a n d 13
4a
6a
10a
13
formula
mol wt
C
39H54NP
C74H72F24N2BPdP*1/3H2O
1599.53
C38H61PdSClPN
736.78
C40H65SClPdPN
764.84
567.83
cryst syst
space group
a, Å
b, Å
c, Å
monoclinic
P21/n
15.2092(5)
9.6929(3)
24.5249(8)
triclinic
P1h
monoclinic
P21/c
13.1700(4)
26.5085(9)
11.5411(4)
monoclinic
P21/n
11.9591(5)
15.8500(7)
23.3435(10)
13.7601(8)
14.3900(8)
21.0682(12)
107.898(1)
100.978(1)
92.510(1)
3873.7(4)
2
R, deg
â, deg
99.420(1)
99.848(1)
104.795(1)
γ, deg
V, Å3
3566.74(20)
4
1.057
1240.95
3969.82(23)
4
1.233
1558.08
0.25 × 0.20 × 0.10
-100
4278.1(3)
4
1.188
1622.11
Z
dens calcd, Mg/m3
F(000)
1.371
1630.24
0.30 × 0.30 × 0.15
cryst dimens, mm
temp, °C
0.30 × 0.30 × 0.25
0.20 × 0.20 × 0.20
radiation (λ, Å)
2θ range, deg
µ, mm-1
total no. of reflns
total no. unique reflns
no. of obsd data
(I>2.5σ(I))
no. of refined params
RF, %
0.71073
5.00-60.00
0.65
56392
11600
5.00-60.00
0.1
41835
6330
5.00-50.00
0.36
31618
12659
5914
5.00-50.00
0.61
36040
7572
5169
8620
6236
587
933
389
407
0.053
0.057
2.4486
0.068
0.075
2.345
0.044
0.054
1.9720
0.038
0.050
1.9215
R
W, %
GOF
3
evaporating solvent, the residue was purified by flash chro-
matography on silica gel (12 × 3.3 cm) in 1:1 hexane/toluene.
Fractions containing the product were evaporated to give
product as a yellowish oil (0.822 g, 88.3%). Rf ) 0.44 (1:2
toluene/hexane). 1H NMR (CDCl3): 7.74 (s, 1H); 7.34-7.10 (m,
3H); 7.09 (s, 2H); 4.09 (septet, 2H; J ) 6.9 Hz); 3.00 (septet,
2H; J ) 6.9 Hz); 2.94 (septet, 1H; J ) 6.9 Hz); 1.52 (s, 6H);
1.31 (d, 6H; J ) 6.9 Hz); 1.24 (unresolved br d, 12H); 1.22 (d,
12H; J ) 6.9 Hz). 13C{1H} (CDCl3, 238 K): 168.5, 154.8, 150.5,
147.8, 137.6, 124.8, 124.1, 122.9, 121.9, 52.2, 34.3, 32.3, 27.7,
25.9, 25.8, 24.1, 23.6, 22.9. Anal. Calcd for C31H47NS: C 79.93,
H 10.17, N 3.01. Found: C 79.78, H 10.22, N 2.98.
[(2,4,6-(i-P r )3C6H2)SCMe2CHdN(2,6-(i-P r )2C6H3)]P d Me-
Cl, 17. Imine 16 (0.200 g, 0.43 mmol) was mixed with (cod)-
PdMeCl (0.114 g, 0.43 mmol) and benzonitrile (5 mL). The
reaction mixture was stirred at RT for 1 h followed by
evaporation of benzonitrile at 0.2 mm/RT overnight. The
residue was coevaporated with toluene (2 × 5 mL), dissolved
in CH2Cl2 (5 mL), and filtered through Celite. After evapora-
tion and trituration with hexanes a yellowish solid was
obtained (0.237 g, 88.5%), as a ca. 7:1 isomer mixture (ratio of
Me peaks at 0.57 (major) and 0.79 ppm (minor)). The config-
uration at the palladium center was verified by X-ray crystal-
lography; however, it was not possible to fully refine the
structure due to twinning of the crystals. Major isomer 1H
NMR (CDCl3): 7.55 (s, 1H); 7.25-7.08 (m, 5H); 4.38 (septet,
2H; J ) 6.8 Hz); 3.16 (septet, 2H; J ) 6.8 Hz); 2.93 (septet,
1H; J ) 6.9 Hz); 1.55 (s, 6H); 1.44 (d, 6H; J ) 6.8 Hz); 1.37 (d,
12H; J ) 6.8 Hz); 1.28 (d, 6H; J ) 6.9 Hz); 1.15 (d, 6H; J )
6.8 Hz), 0.57 (s, 3H). Major isomer 13C{1H} (CDCl3): 175.4,
154.2, 153.2, 144.5, 139.4, 127.1, 123.7, 123.4, 119.8, 62.9, 34.4,
32.6, 28.3, 26.6, 25.7, 25.0, 24.0, 23.9, 23.5, -6.2. Anal. Calcd
for C32H50ClNPdS: C 61.72, H 8.09, N 2.25. Found: C 61.86,
H 8.12, N 2.31.
[((2,4,6-(i-P r ) C6H 2)SCMe2CH dN(2,6-(i-P r )2C6H 3))P d -
(NCMe)Me]+B(Ar F )4-, 18. The synthesis was performed as
in the case of 6a , using 17 (0.08 g, 0.128 mmol) and NaB(ArF)4
(0.114 g, 0.128 mmol). Product was obtained as a yellowish
powder, 0.180 g (96.9%). The configuration at the palladium
center was assigned by analogy with 17. 1H NMR (CD2Cl2):
7.71 (s, 1H); 7.34-7.25 (m, 3H); 7.24 (s, 2H); 4.18 (septet, 2H;
J ) 6.8 Hz); 3.05 (septet, 2H; J ) 6.8 Hz); 2.96 (septet, 1H;
J ) 6.9 Hz); 1.73 (s, 3H); 1.60 (s, 6H); 1.41 (d, 6H; J ) 6.8
Hz); 1.39 (d, 6H; J ) 6.8 Hz); 1.34 (d, 6H; J ) 6.8 Hz); 1.28 (d,
6H; J ) 6.9 Hz); 1.19 (d, 6H; J ) 6.8 Hz); 0.56 (s, 3H). 13C{1H}
(CD2Cl2): 177.9; 155.3; 154.3; 143.3; 139.5; 128.6; 124.8; 124.5;
120.1; 67.5; 34.9; 33.5; 28.8; 26.5; 25.5; 25.1; 24.0; 23.8; 23.3;
2.1; -2.9. One aromatic carbon is unaccounted for. Anal. Calcd
for C66H65BF24N2PdS: C 53.14, H 4.39, N 1.89. Found: C 53.42,
H 4.43, N 1.82.
X-r a y Cr ysta l Str u ctu r es. Diffraction data were collected
on a Bruker SMART diffractometer using the ω-scan mode.
Refinement was carried out with the full-matrix least-squares
method based on F (NCRVAX) with anisotropic thermal
parameters for all non-hydrogen atoms. Hydrogen atoms were
inserted in calculated positions and refined riding with the
corresponding atom. Complete details of X-ray data collection
are given below in Table 4. For 4a , I > 3.0σ(I).
Ack n ow led gm en t. We are grateful to DuPont for
support of this research.
Su p p or tin g In for m a tion Ava ila ble: X-ray crystallogra-
phy data for 4a , 6a , 10a , and 13 and graphs for the determi-
nation of rates of migratory insertion. This material is
available free of charge via the Internet at http://pubs.acs.org.
OM020631X