Synthesis and structure of platinum and palladium complexes of dimesitylphosphine

Article abstract of DOI:10.1016/S0277-5387(02)01184-1

Treatment of Pd(tmeda)Me₂ with dimesitylphosphine (PMes₂H, L) gave cis-PdL₂Me₂ (1). trans-ML₂Cl₂ (M = Pd (2), Pt (3)) were prepared from a variety of starting materials. The reaction of Pt(cod)Cl₂ with L gave cis-PtL₂Cl₂ (4), which reacted with PPh₃ to yield cis-Pt(L)(PPh₃)Cl₂ (5). cis-PtL₂(Me)(Cl) (6) was prepared from L and Pt(cod)(Me)(Cl), while reaction of L with Pt(cod)(Et)(I) gave cis-PtL₂(Et)(I) (7), which isomerized to trans-PtL₂(Et)(I) (8). The phosphine-borane PMes₂H·BH₃ (9) was made by reaction of L with BH₃·SMe₂. Crystal structures of 2·2CH₂Cl₂, 4·CH₂Cl₂, 5·2CH₂Cl₂, 6, and 9 provided 7information on the steric bulk of L (cone angle ca. 149°). Restricted rotation about the Pt-P and P-C bonds in complexes 4-8 was studied by variable temperature NMR spectroscopy.

Full text of DOI:10.1016/S0277-5387(02)01184-1

Polyhedron 21 (2002) 2409ꢁ2419
/
www.elsevier.com/locate/poly
Synthesis and structure of platinum and palladium complexes of
dimesitylphosphine
Elizabeth M. Pelczar a, Emily A. Nytko a, Michael A. Zhuravel a, Jeremy M. Smith a,1,
David S. Glueck a,*, Roger Sommer b, Christopher D. Incarvito b, Arnold L. Rheingold b
a 6128 Burke Laboratory, Department of Chemistry, Dartmouth College, Hanover, NH 03755, USA
b Department of Chemistry, University of Delaware, Newark, DE 19716, USA
Received 1 May 2002; accepted 31 July 2002
Abstract
Treatment of Pd(tmeda)Me2 with dimesitylphosphine (PMes2H, L) gave cis-PdL2Me2 (1). trans-ML2Cl2 (MꢀPd (2), Pt (3)) were
/
prepared from a variety of starting materials. The reaction of Pt(cod)Cl2 with L gave cis-PtL2Cl2 (4), which reacted with PPh3 to
yield cis-Pt(L)(PPh3)Cl2 (5). cis-PtL2(Me)(Cl) (6) was prepared from L and Pt(cod)(Me)(Cl), while reaction of L with Pt(cod)(Et)(I)
gave cis-PtL2(Et)(I) (7), which isomerized to trans-PtL2(Et)(I) (8). The phosphineꢁ
of L with BH3×SMe2. Crystal structures of 2×2CH2Cl2, 4×CH2Cl2, 5×2CH2Cl2, 6, and 9 provided 7information on the steric bulk of
P and PÃC bonds in complexes 4ꢁ8 was studied by variable temperature
/
borane PMes2H×/BH3 (9) was made by reaction
/
/
/
/
L (cone angle ca. 1498). Restricted rotation about the PtÃ
/
/
/
NMR spectroscopy.
# 2002 Elsevier Science Ltd. All rights reserved.
Keywords: Dimesitylphosphine; Secondary phosphine; X-ray crystallography; NMR; Cone angle; Fluxional
1. Introduction
X-ray structural studies provide information on the
steric and electronic properties of this ligand, as well as
the dynamics of its complexes in solution [5].
Since reaction of secondary phosphines with metal
complexes often results in cleavage of the PÃ
/
H bond
and formation of a phosphido (PR2) complex, it is
difficult to study their ligand properties for comparison
with the well-known tertiary phosphines [1]. Secondary
phosphines with bulky substituents are less prone to
2. Results and discussion
Treatment of PdMe2(tmeda) [6] with 2 equiv. of L
gave cis-Pd(PMes2H)2Me2 (1, Scheme 1). The cis
geometry was established by NMR; thus, the 31P
reactions of the PÃ/H bond, which has enabled extensive
study of the coordination chemistry of, for example, P(t-
Bu)2H [2]. Despite the steric bulk of dimesitylphosphine
NMR spectrum (C6D6) shows only a doublet (JPH
ꢀ
/
2
339 Hz) at d ꢂ
3JPH couplings in the AA?XX? spin system [7]. The PdÃ
Me 13C NMR signal (C6D6) appears at d 5.1 (dd, Jꢀ
/46.6, consistent with small JPP and
(PMes2HÄ
/
L, Mesꢀ
/
2,4,6-Me3C6H2), we have pre-
/
viously reported oxidative addition of its PÃ
/
H and PÃ
/
/
C bonds to Pt(0) [3], as well as cyclometalation of a Mes
o-Me group in Pt(II) and Pd(II) complexes [4]. Here we
describe the synthesis of a series of less reactive Pt(II)
and Pd(II) complexes of dimesitylphosphine. NMR and
95, 10 Hz), as expected for the cis isomer. Tables 1 and 2
contain additional selected NMR and IR (nPH) data
characterizing the PMes2H ligands in this and related
complexes (see below).
Initially prepared samples of 1 were off-white, but
they rapidly turned purple in solution or the solid state.
Although we were unable to remove the unidentified
purple material, these samples were analytically and
spectroscopically pure, suggesting that only traces of a
* Corresponding author
E-mail address: glueck@dartmouth.edu (D.S. Glueck).
1
Department of Chemistry, University of Rochester, Rochester,
NY 14627-0216, USA.
0277-5387/02/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved.
PII: S 0 2 7 7 - 5 3 8 7 ( 0 2 ) 0 1 1 8 4 - 1

2410
E.M. Pelczar et al. / Polyhedron 21 (2002) 2409ꢁ2419
/
either
Pd(cod)Cl2
(codꢀ/1,5-cyclooctadiene)
or
Pd(NCPh)2Cl2 (Scheme 1). The trans stereochemistry
of 2 and its Pt analogue 3 (see below) was established by
NMR. Analysis of the PMes2H AA?XX? patterns in the
1H and 31P NMR spectra [7] and simulation using
gNMR [10] gave the coupling constants shown in Table
2. The large JPP values (598 and 523 Hz, respectively)
are consistent with the trans geometry [11].
Scheme 1.
Interestingly, treatment of 2 with 2 equiv. of MeLi
gave partial conversion to the dimethyl complex 1
(Scheme 1). The steric bulk of PMes2H would seem to
highly colored impurity were present. Complex 1 was
thermally stable, decomposing slowly in toluene at
105 8C over several days to give unidentified products
[8].
Addition of 2 equiv. of PMes2H to PdCl2 in acidic
ethanol gave trans-PdL2Cl2 (2) [9]. This complex could
also be prepared by addition of 2 equiv. of PMes2H to
contraindicate the observed trans ꢁcis isomerization, but
/
similar results have been observed previously. For
example, trans-Pd(PPh3)2Me2 isomerizes on heating in
DMSO to the cis complex [8a]. Electronic arguments
based on the strong trans influence of the methyl group
Table 1
Selected NMR and IR data for cis-dimesitylphosphine complexes
a
Complex
d(P)
1JPH
1JPtÃP
d(PH)
n(PH)
PdL2Me2 (1)
PtL2Cl2 (4)
ꢂ46.6
ꢂ48.1
ꢂ44.2
ꢂ51.1
ꢂ41.6
ꢂ39.6
ꢂ38.1
ꢂ49.2
ꢂ31.8
ꢂ47.3
ꢂ33.7
ꢂ48.1
ꢂ34.9
ꢂ43.2
ꢂ36.4
ꢂ44.1
ꢂ43.5
ꢂ46.9
ꢂ41.7
ꢂ46.3
ꢂ40.1
ꢂ44.0
ꢂ37.1
ꢂ41.2
ꢂ35.8
ꢂ39.4
339
414
408
430
414
408
372
5.97
6.34
2388
2422
b
3444
3631
c
c
c
d
PtL2Cl2 (4A)
PtL2Cl2 (4B)
PtL2Cl2 (4C)
5.55
6.77
e
3302
f
g
5.16
h
i
j
PtL(PPh3)Cl2 (5)
PtL2(Me)(Cl) (6)
3538
1505
4189
1777
3996
1726
4016
1341
4207
1444
4234
4315
1350
4355
1325
4309
1248
4166
1627
4132
1563
4.89
2413
2400
f
m
m
m
m
f
403
m
k
k
k
k
PtL2(Me)(Cl) (6A)
PtL2(Me)(Cl) (6B)
PtL2(Me)(Cl) (6C)
PtL2(Me)(Cl) (6D)
PtL2(Et)(I) (7)
m
m
m
388
368
386
382
401
375
389
361
409
362
2402
l
m
m
m
PtL2(Et)(I) (7A)
l
PtL2(Et)(I) (7B)
l
PtL2(Et)(I) (7C)
l
PtL2(Et)(I) (7D)
m
Temperature: 21 8C unless noted; solvents: C6D6 for 1, 6, CDCl3 for 5, 7. 31P NMR chemical shift reference: external 85% H3PO4; coupling
a
constants in Hz; IR data in cmꢂ1 for KBr pellets.
b
C6D5Cl, 100 8C.
c
CD2Cl2, ꢂ70 8C. Two major species (A, B) and a minor one (C) in ca. 1:1:0.15 ratio were observed.
Apparent dd, Jꢀ408, 10.
Apparent d, Jꢀ430.
Not observed.
d
e
f
g
Apparent dd, Jꢀ414, 10. In addition, another apparent d (Jꢀ428) at d 6.89 was observed.
Additional 31P NMR data: d 14.5 (d, Jꢀ14, JPtÃPꢀ3589, PPh3).
h
i
d, Jꢀ14.
dd, Jꢀ408, 12.
j
k
CD2Cl2, ꢂ70 8C. Four isomers Aꢁ
/
D (ratio 2.9:2.6:1.7:1) were observed; for isomers Bꢁ
D (ratio 7.3:4.4:5.6:1) were observed.
See the text and Section 4 for further discussion and low-temperature 1H NMR results.
/D, JPPꢀ8.
l
CD2Cl2, ꢂ40 8C. Four isomers Aꢁ
/
m

E.M. Pelczar et al. / Polyhedron 21 (2002) 2409ꢁ
/2419
2411
Table 2
Selected NMR and IR data for trans-dimesitylphosphine complexes
a
Complex
d(P)
1JPtÃP
2JPP
1JPH
3JPH
d(PH)
n(PH)
PdL2Cl2 (2)
PtL2Cl2 (3)
PtL2(Et)(I) (8)
ꢂ38.3
ꢂ37.9
ꢂ37.1
598
523
492
386
396
389
ꢂ2
ꢂ2
ꢂ3
6.52
6.66
2400
2404
2395
2506
3123
b,c
d
7.24
a
Temperature: 21 8C unless noted; solvents: CDCl3 for 2, 3, C6D5Cl for 8; 31P NMR chemical shift reference: external 85% H3PO4; coupling
constants in Hz; IR data in cmꢂ1 for KBr pellets.
b
80 8C.
c
Additional 31P{1H} NMR data for 8 (CD2Cl2, ꢂ70 8C): Four isomers (Aꢁ
D) with approximate ratio 4.8:2.7:1:1 were observed; d ꢂ39.4
/
(JPtÃPꢀ3069, A), ꢂ29.0 (JPtÃPꢀ3153, B), ꢂ37.3 (JPtÃPꢀ3006, C), ꢂ26.7 (JPtÃPꢀ3153, D). See the text and Section 4 for additional discussion of
these and related low-temperature 1H NMR spectra.
d
Apparent d, Jꢀ384, JPtÃHꢀ26, perhaps the most intense two peaks of an AA?XX? pattern.
have been advanced to explain this behavior (‘‘anti-
symbiotic effect’’ [12], ‘‘transphobia’’ [13]).
metry, 31P NMR monitoring of the reaction mixture
showed formation of PMes2H and the presence of
unreacted PPh3. Recrystallization from CH2Cl2/petro-
leum ether gave white crystals, identified by NMR as the
Reaction of 2 equiv. of L with three different
platinum sources [K2PtCl4, PtCl2, and PtCl2(NCPh)2]
yielded trans-Pt(PMes2H)2Cl2 (3) as a yellow powder
(Scheme 1, Table 2). In contrast, treatment of
Pt(cod)Cl2 with L gave cis-Pt(PMes2H)2Cl2 (4) as shown
in Scheme 2. Its room temperature NMR spectra
contain very broad peaks, attributed to restricted
cis isomer (JPP
ꢀ14 Hz, Table 1).
/
Reaction of Pt(cod)(Me)(Cl) with 2 equiv. of L
yielded cis-Pt(PMes2H)2(Me)(Cl) (6, Scheme 3). The
cis geometry was established by 31P NMR (see Table 1)
and by the PtÃ
/
Me 13C NMR signal (d 3.5, dd, Jꢀ
96, 6
/
Hz, CD2Cl2). Similarly, treatment of Pt(cod)(Et)(I) with
2 equiv. of L gave white cis-Pt(PMes2H)2(Et)(I) (7,
Table 1), which readily isomerized on standing or gentle
heating to the yellow trans isomer (8, Scheme 3). The
room temperature NMR spectra of complex 8 were very
broad, indicative of a dynamic process (see Section 2.2),
but at 80 8C in C6D5Cl, it showed the expected AA?XX?
31P NMR spectrum (Table 2).
rotation about the PÃ
/
C and/or PtÃ
/
P bonds (see below).
At high temperature (100 8C, C6D5Cl) a sharp average
spectrum consistent with the cis geometry is observed
(Table 1).
The reactivity of 4 was briefly examined (Scheme 2).
Irradiation of a CD2Cl2 solution of 4 with a mercury
lamp caused slow conversion to the trans isomer 3,
consistent with literature reports of related photoche-
mical cis ꢁ
/
trans isomerizations in PtL2X2 complexes
2.1. Solid-state structures
(LꢀPPh3, pyridine, isoquinoline, Xꢀ
/
/Cl, Br) [9,14].
Treatment of Pt(cod)Cl2 with 3 equiv. of PMes2H gave a
mixture of 4 and PMes2H, which did not undergo
exchange on the NMR time scale, while 1 equiv. of
PMes2H gave a mixture of 4 and unreacted Pt(cod)Cl2,
The X-ray crystal structures of trans-PdL2Cl2 (2×
2CH2Cl2), cis-PtL2Cl2 (4×CH2Cl2), cis-PtL(PPh3)Cl2
(5×2CH2Cl2), cis-PtL2(Me)(Cl) (6) and the phosphineꢁ
borane L-BH3 (9, see Section 4) were determined to
investigate the effect of the bulky phosphine on the
structures of its simple coordination complexes. For
/
/
/
/
1
as shown by the H NMR spectrum. Addition of more
phosphine completed the conversion to 4. PMes2H was
readily displaced from 4 by 2 equiv. of dppe (dppeꢀ
/
thermal ellipsoid plots, see Figs. 1ꢁ5; crystal data is
/
Ph2PCH2CH2PPh2) to yield [Pt(dppe)2][Cl]2 [15]. Heat-
ing 4 at 45 8C in CH2Cl2 with 2 equiv. of PPh3 gave cis-
Pt(PMes2H)(PPh3)Cl2 (5). Consistent with the stoichio-
summarized in Table 3, and additional details are
included in Sections 4 and 5. See the figure captions
and Tables 4 and 5 for selected bond lengths and angles.
The structure of 2 shows a minor distortion from ideal
square planar geometry, and PdÃ
/
P and PdÃ/Cl bond
Scheme 2.
Scheme 3.

2412
E.M. Pelczar et al. / Polyhedron 21 (2002) 2409ꢁ2419
/
Fig. 3. Thermal ellipsoid plot (25% probability) of cis-
2CH2Cl2). The solvent molecule and hydro-
gen atoms, except the one on P, have been removed for clarity.
Fig. 1. ORTEP diagram of trans-Pd(PMes2H)2Cl2 (2×2CH2Cl2), with
thermal ellipsoids at 30% probability. The solvent molecules and
hydrogen atoms, except those on P, have been removed for clarity.
/
Pt(PMes2H)(PPh3)Cl2 (5×
/
˚
Selected bond lengths (A) and angles (8): PdÃ
/
Cl(1) 2.3028(7), PdÃ
P(1A) 2.3057(7), P(1)Ã
PdÃCl(1A) 180.0, Cl(1)Ã
P(1) 86.09(2), Cl(1)ÃPdÃP(1A)
P(1) 93.91(2), P(1)ÃPdÃP(1A) 180.0, C(10)Ã
C(1) 110.45(12).
/
Cl(1A) 2.3028(7), PdÃ
C(10) 1.819(3), P(1)ÃC(1) 1.822(3), Cl(1)Ã
PdÃP(1) 93.91(2), Cl(1A)ÃPdÃ
86.09(2), Cl(1)ÃPdÃ
P(1A)Ã
/
P(1) 2.3057(7), PdÃ
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
Fig. 4. ORTEP diagram of cis-Pt(PMes2H)2(Me)(Cl) (6), with thermal
ellipsoids at 30% probability. The hydrogen atoms, except those on P,
have been removed for clarity.
Fig. 2. ORTEP diagram of cis-Pt(PMes2H)2Cl2 (4×CH2Cl2), with
/
thermal ellipsoids at 30% probability. The solvent molecule and
hydrogen atoms, except those on P, have been removed for clarity.
lengths typical of those in square planar phosphine
complexes [16]. The cis-Pt complexes 4ꢁ
all show slight distortions from square planar geometry.
As might be expected, the PÃPtÃP bond angles, which
/6 (see Table 4)
/
/
range from 95.65(7)8 to 97.07(7)8 are larger than the
ideal value, presumably due to steric hindrance between
the bulky phosphines, as previously observed in cis-
Pt(PPh3)2Cl2 (Table 4) and related structures [17]. The
close similarity between the structures of 4, 5 and cis-
Pt(PPh3)2Cl2 suggests that L and PPh3 have comparable
steric and electronic properties. This is consistent with
the similar JPtÃP values found for these phosphines in 5
(3538 Hz for L, 3589 Hz for PPh3, CDCl3). As expected
Fig. 5. Thermal ellipsoid plot (25% probability) of PMes2H×
/
BH3 (9).
Hydrogen atoms, except those on P and B, have been removed for
˚
clarity. Selected bond lengths (A) and angles (8): PÃ
C(1) 1.824(3), PÃC(10) 1.829(3), PÃB(1) 1.938(4), H(1)Ã
97.3(11), H(1)ÃPÃC(1) 104.0(11), H(1)ÃPÃB(1) 108.3(12), C(10)Ã
C(1) 110.71(12), C(10)ÃPÃB(1) 124.41(15), C(1)ÃPÃB(1) 109.62(15).
/
H(1) 1.35(3), PÃ
PÃC(10)
PÃ
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
In the structure of phosphineꢁborane 9, the PH and
/
from trans influence trends, the PtÃ
/
P bond trans to the
˚
methyl group in 6 is longer [2.3311(17) A] than the one
BH3 hydrogens were found and refined freely. The
geometry around phosphorus is tetrahedral as expected,
˚
trans to chloride [2.214(2) A] [18].
though the C(10)Ã
/
PÃ/B bond angle is somewhat larger

E.M. Pelczar et al. / Polyhedron 21 (2002) 2409ꢁ
/2419
2413
Table 3
Crystallographic data for trans-PdL2Cl2 (2×2CH2Cl2), cis-PtL2Cl2 (4×CH2Cl2), cis-PtL(PPh3)Cl2 (5×2CH2Cl2), cis-PtL2(Me)(Cl) (6), and L×BH3 (9)
Complex
2×2CH2Cl2
38H50Cl6P2Pd
4×CH2Cl2
5×2CH2Cl2
6
9
Empirical formula
Formula weight
Space group
C
C37H48Cl4P2Pt
891.58
P21/n
C38H42Cl6P2Pt
968.45
P21/n
C37H49ClP2Pt
786.24
P21/n
C18H26BP
284.17
P21/c
887.82
P21/n
Temperature (K)
˚
173(2)
11.3321(6)
11.8745(7)
15.9474(8)
90
173(2)
173(2)
11.6372(13)
22.830(3)
15.2546(18)
90
173(2)
14.2510(9)
15.1847(11)
16.2727(11)
90
173(2)
8.1454(14)
11.3460(19)
19.258(3)
90
a (A)
˚
12.4534(10)
19.3221(15)
16.1326(12)
90
b (A)
˚
c (A)
a (8)
b (8)
107.6950(10)
90
106.418(2)
90
98.820(3)
90
97.257(2)
90
98.973(4)
90
g (8)
3
V (A )
˚
2044.40(19)
2
3723.6(5)
4
4004.9(8)
4
3493.2(4)
4
1758.0(5)
4
Z
˚
l (A)
0.71073
1.442
0.951
0.71073
1.590
4.167
0.71073
1.606
4.010
0.71073
1.495
4.209
0.71073
1.074
0.146
Dcalc (g cmꢂ3
)
m (mmꢂ1
R(F) (%)
)
a
3.59
8.44
2.98
6.52
4.02
8.91
4.79
7.87
5.53
13.50
R(wF2) (%)
a
a
Quantity minimizedꢀR(wF2)ꢀ[S[w(F/o2
/
ꢂF/2c
)/
2]/S[w(F/2o
)/
2]]1/2; RꢀSD/S(Fo), DꢀIj(FoꢂFc)jI.
˚
B distance of 2.28 A in the case of 9 [22]. Although
than the ideal angle at 124.41(15)8. The PÃ
/
B bond
PÃ
/
˚
length (1.938(4) A) is typical of those in phosphineꢁ
/
this is longer than the experimental distance, this choice
allows comparison to the results for the metal com-
plexes. As shown in Table 6, the cone angle falls in a
narrow range in this series of complexes, although
significant differences can be seen even within a single
compound containing two phosphines, such as 4. The
average cone angle is approximately 1498. Consistent
with the discussion above, the crystallographically
determined cone angles for L and PPh3 in 5 are similar;
boranes, for which a recently reported range is 1.832ꢁ
˚
1.983 A [19]. Comparison to the structure of PMes2H
[20] (Table 5) shows that borane complexation has little
/
effect on the structure of the phosphine. The PÃ
become slightly shorter and the C(1)ÃPÃC(10) bond
angle is increased.
/
C bonds
/
/
The program STERIC [21] was used to determine the
cone angle of L from the crystal structure data, setting a
Table 4
Selected bond lengths (A) and angles (8) for cis-Pt dimesitylphosphine complexes 4ꢁ
a
˚
/
6
b
Complex
PtL2Cl2 (4×CH2Cl2)
PtL(PPh3)Cl2 (5×2CH2Cl2)
PtL2(Me)(Cl) (6)
Pt(PPh3)2Cl2×C3H6O
Bond lengths
PtÃP1
PtÃP2
PtÃCl1
2.2481(9)
2.2315(9)
2.3445(10)
2.3385(9)
2.2438(19)
2.2444(19)
2.3519(19)
2.3478(19)
2.3311(17)
2.214(2)
2.251(2)
2.265(2)
2.333(2)
2.356(2)
2.3591(19)
2.084(6)
PtÃCl2 (Me)
Bond angles
P1ÃPtÃP2
96.93(3)
84.13(3)
173.90(3)
89.79(4)
174.46(4)
89.10(3)
95.65(7)
89.63(7)
175.02(6)
88.15(7)
174.61(6)
86.68(7)
97.07(7)
85.29(7)
172.0(2)
87.3(2)
97.8(1)
89.8(1)
176.9(1)
87.1(1)
172.4(1)
85.3(1)
P1ÃPtÃCl1
P1ÃPtÃCl2 (Me)
Cl1ÃPtÃCl2 (Me)
Cl1ÃPtÃP2
177.19(7)
90.3(2)
P2ÃPtÃCl2 (Me)
a
For 4×CH2Cl2, P1ꢀP2ꢀL; for 5×2CH2Cl2, P1ꢀL, P2ꢀPPh3; for 6, P1ꢀP2ꢀL, P1 trans to Me, P2 trans to Cl. Note that the atom numbering
in Fig. 5 for 6 is slightly different than the convention used here.
b
Ref. [17].

2414
E.M. Pelczar et al. / Polyhedron 21 (2002) 2409ꢁ2419
/
Table 5
Low-temperature 1H NMR studies (ꢂ
70 8C, CD2Cl2)
/
a
˚
Selected bond lengths (A) and angles (8) in PMes2H
PMes2H×BH3 (9)
and
provided additional information on the dynamic pro-
cesses in 4. As detailed in Section 4, 12 aryl proton
signals (8 from the major and 4 from the minor isomers)
and 18 methyl signals (12 major, 6 minor) were
observed. These observations can be explained if, in
Complex
PMes2H
PMes2H×BH3 (9)
Bond lengths
PÃC(1)
PÃC(10)
PÃH(1)
1.862(7)
1.864(7)
1.36(7)
1.824(3)
1.829(3)
1.35(3)
the two major isomers, rotation about the PÃ
P bonds is slow on the NMR time scale. If rotation
about the PÃC bond is slow, the o-Me and m-aryl
protons are inequivalent in a given Mes group; if
rotation about the PtÃP bond is slow, then there are
/
C and PtÃ
/
/
Bond angles
C(1)ÃPÃC(10)
C(1)ÃPÃH(1)
C(10)ÃPÃH(1)
107.0(3)
109(3)
107(3)
110.71(12)
104.0(11)
97.3(11)
/
two types of mesityl groups in a given PMes2H. The
crystal structure (Fig. 2), if maintained in solution at low
temperature, would be consistent with these observa-
tions. The two major isomers might then be syn and anti
conformers, as reported for trans-Pt[P(t-Bu)2H]2Cl2
[23].
a
Ref. [20].
Table 6
Cone angle data for dimesitylphosphine complexes
a
Four PÃ
/
H resonances were also observed (Table 1).
Three of these are easily assigned, one each to the major
Complex
Cone angle (8)
trans-PdL2Cl2 (2×2CH2Cl2)
cis-PtL2Cl2 (4×CH2Cl2)
cis-PtL(PPh3)Cl2 (5×2CH2Cl2)
cis-PtL2(Me)(Cl) (6)
147
152, 142
and minor isomers, from matching the PÃ
/
H couplings in
the low temperature 1H NMR spectrum with those
obtained in the low temperature 31P NMR spectrum,
b
148
156, 154
146
143, 150
but the origin of the fourth signal is not clear. These PÃ
/
L×BH3 (9)
cis-Pt(PPh3)2Cl2×C3H6O
c
H resonances are expected to show an AA?XX? pattern,
but either simple doublets or doublet of doublets
a
See Section 4 for details of the calculations.
PPh3 cone angleꢀ1548.
Ref. [17].
2
patterns were observed. If the JPP and JPH couplings
3
b
c
are small, then the signals would appear as a doublet.
2
The doublet of doublets patterns could arise if JPP is
small. Alternatively, the observed resonances could be
due to the inner lines of an AA?XX? pattern, if the low
intensity outer peaks are not observed [7].
compare to Tolman’s reported cone angle of 1458 for
PPh3 [22].
Similarly, at ꢂ
/
20 8C in CD2Cl2, the rotation about
the PÃC and PtÃP bonds in 5 is slow on the NMR time
/
/
2.2. Solution structures: fluxional processes
scale, so each of the Mes m-aryl protons and o-Me
groups is inequivalent, consistent with the conformation
found in the crystal structure (Fig. 3). Thus, four sharp
peaks for the Mes m-aryl protons were observed from
6.92 to 6.63 ppm, and four o-Me signals appeared at d
3.38, 2.50, 1.85, and 1.20. Because the two Mes groups
are inequivalent, two separate p-Me resonances were
observed at d 2.25 and 2.23.
Conformational isomerism due to restricted rotation
has often been observed in metal complexes of bulky
secondary phosphines. For example, Shaw reported that
room-temperature solutions of trans-Pt[P(t-Bu)2H]2Cl2
contained two conformational isomers; this complex has
recently been studied in more detail by Mastrorilli et al.
[23]. Similarly, Bushweller’s detailed investigation of
The related complexes 6 and 7 showed similar
fluxional behavior, again ascribed to restricted rotation
trans-Rh[P(t-Bu)2H]2(CO)(X) (Xꢀ
eral conformations as a result of restricted rotation
P bonds [24], and analogous behavior
/halide) revealed sev-
about the PtÃ
/
P and PÃ
/
C bonds, giving rise to four
different isomers in each case at low temperature. This
about the RhÃ
/
could be observed most clearly by 31P NMR (Table 1).
was observed for Ir[P(t-Bu)2H]3(Cl) [2c]. We observed
similar phenomena in Pt dimesitylphosphine complexes
Five and six of the expected eight PÃ
/
H resonances could
also be observed by low-temperature 1H NMR for 6 and
7, respectively (see Section 4 for details).
4ꢁ8 by low-temperature NMR spectroscopy.
/
Although the room-temperature 31P NMR spectrum
of cis-PtL2Cl2 (4) was very broad, three different signals
trans-PtL2(Et)(I) (8) also showed broad peaks in the
room temperature NMR spectra. As for the cis isomer
7, four isomers were observed by low-temperature 31P
NMR (Table 2). However, the lines in the expected
AA?XX? patterns could not all be resolved because of
weak, overlapping signals. Similarly, the 1H NMR
in about a 1:1:0.15 ratio were observed at ꢂ70 8C in
/
CD2Cl2 (Table 1). We assign these to two major isomers
(A and B) and one minor one (C), although we cannot
rule out the possibility that the A and B signals are in
fact due to a single conformer which contains two
inequivalent dimesitylphosphine ligands [24].
spectrum (CD2Cl2, ꢂ70 8C) revealed the most intense
/

E.M. Pelczar et al. / Polyhedron 21 (2002) 2409ꢁ
/2419
2415
signals of the four expected PH AA?XX? patterns;
however, two of these peaks were obscured by Mes
resonances (see Table 2 and Section 4).
4.2. cis-Pd(PMes2H)2Me2 (1). Method 1
Pd(tmeda)Me2 (80 mg, 0.32 mmol) and PMes2H (165
mg, 0.610 mmol) were dissolved in 10 ml of THF to give
a pinkꢁred solution. The THF was removed under
/
vacuum to give a brownish white solid, which was
washed with petroleum ether (4 ml). The resulting
blood-red solution was removed using a pipet to give a
pink solid, which was dried under vacuum to yield 189
mg (88%) of the product.
3. Conclusion
We prepared several simple coordination complexes
of the bulky secondary phosphine PMes2H. Its crystal-
lographically determined cone angle of approximately
1498 is comparable to that of PPh3, and comparison of
the structures of cis-PtL2Cl2 (4), cis-PtL(PPh3)Cl2 (5),
and cis-Pt(PPh3)2Cl2 shows these ligands to have similar
steric and electronic properties. The bulk of dimesityl-
phosphine is reflected in the dynamic properties of its
complexes in solution at low temperature, where re-
Anal. Calc. for C44H52P2Pd: C, 67.40; H, 7.74. Found:
C, 67.23; H, 7.32%. 1H NMR (C6D6): d 6.55 (8H, Mes),
5.97 (d, JPH
2.01 (12H, p-Me), 1.00 (m, 6H, PdÃ
(C6D6): d 142.7 (Mes), 139.1 (Mes), 130.2 (t, Jꢀ
Mes), 126.3 (d, Jꢀ26, Mes), 23.7 (Me), 21.2 (Me), 5.0
(dd, Jꢀ Me). IR: 3433, 2922, 2388, 1727,
ꢀ
/
339, 2H, PH), 2.33 (broad, 24H, o-Me),
Me). 13C{1H} NMR
3,
/
/
/
/
105, 10, PdÃ
/
1600, 1450, 1377, 1133, 1027, 844, 694, 616, 550.
stricted rotation about PtÃ
frequently observed.
/
P and PÃ/C(Mes) bonds was
4.3. Method 2
A pale yellow solution of trans-Pd(PMes2H)2Cl2 (26
mg, 3.6ꢃ
was cooled to ꢂ
(106 ml of 1.4 M solution in ether, 0.15 mmol). The
resulting golden solution was stirred for 1 h at ꢂ78 8C,
/
10ꢂ2 mmol, 2, see below) in 10 ml of THF
4. Experimental
/
78 8C and treated with methyllithium
/
4.1. General
then quenched by the addition of one drop of water,
which turned the solution orange. The solution was
concentrated under vacuum and transferred to a NMR
tube. The 31P NMR spectrum showed partial conversion
(73%) of the dichloro complex 2 to the dimethyl
Unless otherwise noted, all reactions and manipula-
tions were performed in dry glassware under a nitrogen
atmosphere at 20 8C in a dry box or using standard
Schlenk techniques. Petroleum ether (b.p. 38ꢁ53 8C),
/
complex 1. 31P NMR (THF/ether): d ꢂ
2), ꢂ48.3 (d, Jꢀ339, 1).
/
34.8 (AA?XX?,
ether, THF, CH2Cl2 and toluene were dried and
degassed using columns with activated alumina [25].
NMR spectra were recorded (at 21 8C unless other-
wise noted) with Varian 300 or 500 MHz spectrometers;
the latter was used for variable temperature studies. H
or 13C NMR chemical shifts are reported versus Me4Si
/
/
4.4. trans-Pd(PMes2H)2Cl2 (2). Method 1
1
PdCl2 (57 mg, 0.32 mmol) was treated with concen-
trated HCl (4 ml) and the brown solution was stirred for
10 min. After addition of 8 ml of absolute ethanol, the
solution was stirred for an additional 5 min. A solution
of PMes2H (174 mg, 0.643 mmol) in 4 ml of ether was
added, causing a yellow precipitate to form immediately.
The mixture was allowed to stir for another 5 min, and
then filtered on a frit. The solid was washed with water
1
and were determined by reference to the residual H or
13C solvent peaks. 31P NMR chemical shifts are reported
versus H3PO4 (85%) used as an external reference.
Coupling constants are reported in Hz, as absolute
values unless noted otherwise. Unless indicated, peaks in
NMR spectra are singlets. Infrared spectra were re-
corded using KBr pellets on a Perkin Elmer 1600 series
FTIR machine and are reported in cmꢂ1. Elemental
analyses were provided by Schwarzkopf Microanalytical
Laboratory. Low resolution FAB Mass Spectroscopy
was performed on a VG ZAB-SE instrument at the
University of Illinois.
(1ꢃ
/
10 ml) and ether (2ꢃ20 ml) and dried on the frit to
/
give 230 mg, 99%. The yellow solid was recrystallized
from methylene chloride/petroleum ether to give yellow
crystals of a methylene chloride solvate, as quantified by
1H NMR integration.
Unless otherwise noted, reagents were from commer-
cial suppliers. The following compounds were made by
the literature methods: Pd(tmeda)Me2 [6], PMes2H [20],
Pd(cod)Cl2 [26], Pd(NCPh)2Cl2 [27], Pt(NCPh)2Cl2 [27],
Pt(cod)Cl2 [28], Pt(cod)(Me)(Cl) [29], and Pt(cod)(Et)(I)
[30].
Anal. Calc. for C36H46Cl2P2Pd×
H, 6.19. Found: C, 57.06; H, 6.12%. 1H NMR (CDCl3):
d 6.85 (8H, Mes), 6.52 (m, JPP 598, JPH 386, JPH?ꢀ
2, 2H, PÃH, AA?XX?), 2.52 (24H, o-Me), 2.25 (12H,
p-Me). 13C{1H} NMR (CDCl3, 21 8C): d 142.5 (t, Jꢀ
5,
Mes), 140.9 (Mes), 130.1 (t, Jꢀ4, Mes), 122.1 (t, Jꢀ24,
/
0.6CH2Cl2: C, 57.17;
ꢀ
/
ꢀ
/
/
ꢂ
/
/
/
/
/

2416
E.M. Pelczar et al. / Polyhedron 21 (2002) 2409ꢁ2419
/
Mes), 23.7 (t, Jꢀ
2400, 1600, 1556, 1449, 1405, 1374, 1264, 1029, 837.
/
4, o-Me), 21.3 (p-Me). IR: 2956, 2922,
below) in 1 ml of CH2Cl2 was suspended about 3 cm
from an Ace-Hanovia Photochemical Lamp with a
mercury bulb. The tube was irradiated and monitored
by 31P{1H} NMR. After 9 h the solution was pale
yellow and the 31P NMR spectrum showed about 10%
conversion of 4 to 3.
4.5. Method 2
A yellow solution of Pd(cod)Cl2 (22 mg, 0.11 mmol)
in methylene chloride was treated with PMes2H (86 mg,
0.32 mmol), causing the solution to turn orange. 31P
NMR (CH2Cl2): d ꢂ
/
41.0 (AA?XX?, JPP
ꢀ
/
597, JPH
ꢀ
/
4.10. cis-PtCl2(PMes2H)2 (4)
386, JPH?ꢀ 0.07). Recrystallization from methylene
/
ꢂ
/
chloride and petroleum ether gave yellow crystals of
compound 2.
A solution of Pt(cod)Cl2 (100 mg, 0.267 mmol) in
CH2Cl2 (4 ml) was treated with PMes2H (145 mg, 0.535
mmol). Petroleum ether (10 ml) was layered on the
methylene chloride and the clear solution was cooled to
4.6. Method 3
ꢂ20 8C, yielding white crystals after several days. The
mother liquor was removed and the crystals dried under
1
vacuum to give 151 mg (70%) of product. H NMR
/
A brown slurry of Pd(NCPh)2Cl2 (22 mg, 5.7ꢃ
10ꢂ2
mmol) in 10 ml of CH2Cl2 was treated with PMes2H
/
(46.5 mg, 0.173 mmol), which gave a homogeneous
yellow solution. 31P{1H} NMR (CH2Cl2): d ꢂ
41.0.
integration and elemental analysis showed that these
crystals contained CH2Cl2.
/
Anal. Calc. for C36H46Cl2P2Pt×
H, 5.49. Found: C, 50.12; H, 5.25%. 31P{1H} NMR
(CD2Cl2, 21 8C): d ꢂ47.5 (very broad, JPtÃP
3508). 1H
/
0.8CH2Cl2: C, 50.54;
4.7. trans-Pt(PMes2H)2Cl2 (3). Method 1
/
ꢀ
/
PMes2H (50 mg, 0.19 mmol) was dissolved in 10 ml of
ethanol with gentle heating, then cooled to room
NMR (CD2Cl2, 21 8C): d 6.78 (broad), 2.39 (very
broad), 2.26 (broad). 13C{1H} NMR (CD2Cl2, 21 8C):
d 142.5 (broad), 141.7, 130.6, 23.7 (broad), 21.1. IR:
3444, 2955, 2911, 2722, 2422, 1600, 1555, 1444, 1405,
1377, 1288, 1255, 1027, 950, 900, 877, 850, 727, 616, 550,
444. FAB mass spectrum (Magic Bullet): m/z 870, 734
(PtPMes2H)(PMes2)ꢄ), 600, 463, 343, 271 (PMes2H),
234, 135, 119 (Mes).
temperature. A redꢁ
/
orange solution of K2PtCl4 (38
10ꢂ2 mmol) in 14 ml of water was added to
mg, 9.1ꢃ
/
the phosphine solution, and a fine white precipitate
immediately formed. The mixture was filtered through a
fine frit, and the solid was air dried to give 38 mg (51%)
of the product as a very fine white powder. Recrystalli-
zation from methylene chloride/petroleum ether gave
yellow crystals of a methylene chloride solvate. These
crystals desolvated under vacuum to give an analytically
pure sample.
1H NMR (CD2Cl2, ꢂ
/
70 8C): Three isomers AꢁC
/
were observed; unless otherwise noted, the 1H NMR
signals are assigned to A and B, with specific assign-
ments given where possible. d 7.02 (C), 6.98 (d, Jꢀ
2H, Mes), 6.94 (2H, Mes), 6.91 (C), 6.89 (d, Jꢀ428, PH,
C), 6.88 (d, Jꢀ3, 2H, Mes), 6.86 (C), 6.82 (2H, Mes),
6.78 (C), 6.77 (d, Jꢀ430, 2H, PH, B), 6.73 (2H, Mes),
6.68 (2H, Mes), 6.52 (2H, Mes), 6.48 (C), 6.11 (2H,
Mes), 5.55 (apparent dd, Jꢀ408, 10, 2H, PH, A), 5.16
(apparent dd, Jꢀ414, 10, PH, C), 3.41 (6H), 3.37 (6H),
/
3,
Anal. Calc. for C36H46Cl2P2Pt: C, 53.60; H, 5.75.
1
Found: C, 53.58; H, 5.91%. H NMR (CDCl3): d 6.85
/
/
(8H, Mes), 6.66 (m, JPP
2H, P-H, AA?XX?), 2.53 (24H, o-Me), 2.25 (12H, p-
Me). 13C{1H} NMR (CDCl3): d 142.6 (t, Jꢀ
6, Mes),
140.7 (Mes), 130.2 (t, Jꢀ4, Mes), 121.5 (t, Jꢀ28, Mes),
23.5 (t, Jꢀ4, o-Me), 21.3 (p-Me). IR: 2956, 2731, 2404,
ꢀ/523, JPH
ꢀ/396, JP?H
ꢀ
/
ꢂ
/
2,
/
/
/
/
/
/
/
3.33 (C), 3.20 (C), 2.65 (6H), 2.42 (C), 2.26 (6H), 2.23
(6H), 2.22 (6H), 2.08 (6H), 2.07 (6H), 2.03 (C), 1.99
(6H), 1.98 (6H), 1.89 (6H), 1.39 (6H), 1.20 (C), 0.90 (C).
1599, 1559, 1446, 1407, 1373, 1289, 1243, 1029, 962, 933,
905, 849, 708, 623, 550, 420.
13C{1H} NMR (CD2Cl2, ꢂ
143.4 (d, Jꢀ14), 143.0 (d, Jꢀ
141.3 (d, Jꢀ6), 141.1 (m), 140.9 (m), 139.9 (m), 139.7
(m), 139.4 (m), 131.0ꢁ130.8 (m), 130.3 (d, Jꢀ10), 129.7
(m), 129.4 (d, Jꢀ8), 129.2 (m), 121.7, 121.2, 118.2,
118.0, 117.9, 117.4, 117.1, 116.7 (m), 27.1 (d, Jꢀ9), 26.4
20.5 (m).
/
60 8C): d 143.9 (d, Jꢀ
/
15),
4.8. Method 2
/
/8), 142.0 (m), 141.5 (m),
/
A CH2Cl2 solution of PtCl2(NCPh)2 (10 mg, 2.2ꢃ
10ꢂ2 mmol) was treated with PMes2H (15 mg, 4.2ꢃ
10ꢂ2 mmol). The 31P{1H} NMR spectrum of the
reaction mixture showed that 3 had formed: d ꢂ37.9
(JPtÃP 2506).
/
/
/
/
/
/
/
(d, Jꢀ
/
10), 22.6ꢁ
/
22.2 (m), 21.7 (m), 20.9ꢁ
/
ꢀ
/
1H NMR (C6D5Cl, 21 8C): d 6.53 (broad, Mes), 2.31
(broad, o-Me), 2.05 (p-Me). 1H NMR (C6D5Cl,
4.9. Method 3
100 8C): d 6.57 (8H, Mes), 6.34 (d, Jꢀ
2.38 (24H, o-Me), 2.06 (12H, p-Me). 31P{1H} NMR
(C6D5Cl, 21 8C): d ꢂ48.7 (very broad).
/
414, 2H, PH),
A NMR tube containing a clear solution of cis-
PtCl2(PMes2H)2 (4) (20 mg, 2.5ꢃ
10ꢂ2 mmol, 4, see
/
/

E.M. Pelczar et al. / Polyhedron 21 (2002) 2409ꢁ
/2419
2417
4.11. cis-Pt(PMes2H)(PPh3)Cl2 (5)
140.8 (Mes), 140.6 (Mes), 140.0 (Mes), 130.2 (m, Mes),
123.5 (broad), 122.5, 121.5 (broad), 23.6ꢁ22.5 (very
broad), 23.1 (m, o-Me), 21.1 (p-Me), 21.0 (p-Me), 3.5
(dd, Jꢀ Me). IR: 3444, 2955, 2911, 2722, 2400,
1600, 1555, 1444, 1405, 1377, 1255, 1200, 1027, 944, 900,
850, 805, 700, 611, 550, 461.
/
PPh3 (49 mg, 0.19 mmol) was dissolved in methylene
chloride (6 ml) to give
a
clear solution. cis-
/
96, 6, PtÃ
/
PtCl2(PMes2H)2 (100 mg, 0.124 mmol) was added. No
color change occurred, and the solid did not dissolve
completely. The solution was filtered through Celite to
give a yellow filtrate. After the solution was left standing
at room temperature overnight, it turned clear. The
solution was heated to 45 8C for 5 h using a water bath.
The solvent was then removed under vacuum to give
white crystals, which were recrystallized from methylene
chloride/petroleum ether to give 51 mg (52%) of white
4.13. cis-Pt(PMes2H)2(Et)(I) (7)
Pt(cod)(Et)(I) (418 mg, 0.910 mmol) was dissolved in
methylene chloride (5 ml). PMes2H (492 mg, 1.82 mmol)
was added. Petroleum ether (3 ml) was layered on top of
the yellow solution. The solution was refrigerated at
3 8C to give off-white crystals (480 mg, 60%, in two
crops).
1
solid which was a CH2Cl2 solvate, according to the H
NMR spectrum in CDCl3. Recrystallization from THF/
ether gave analytically pure material.
Anal. Calc. for C36H38Cl2P2Pt: C, 54.14; H, 4.80.
Anal. Calc. for C38H51IP2Pt: C, 51.18; H, 5.76.
1
Found: C, 51.07; H, 5.85%. H NMR (CDCl3): d 6.71
1
Found: C, 54.45; H, 4.60%. H NMR (CD2Cl2, 21 8C):
(broad, 8H, Mes), 2.23 (broad m, 36H, Me), 1.07
(broad, 5H, Et). The PH peaks were not observed.
13C{1H} NMR (CDCl3): d 143.0 (very broad, Mes),
140.9 (Mes), 140.7 (Mes), 140.0 (Mes), 130.4 (broad m,
d 7.66ꢁ
/
7.62 (m, 6H, Ph), 7.47 (m, 3H, Ph), 7.36ꢁ
/
7.32
(m, 6H, Ph), 6.89ꢁ
/
6.62 (broad, 4H, Mes), 4.89 (dd, Jꢀ
/
409, 12, 1H, PH), 3.42 (broad, 3H, o-Me), 2.54 (broad,
3H, o-Me), 2.26 (6H, p-Me), 1.87 (broad, 3H, o-Me),
Mes), 125.4 (Mes), 124.9 (Mes), 121.5 (Mes), 24.1ꢁ
(very broad, o-Me), 21.8 (p-Me), 21.7 (p-Me), 21.6 (p-
Me), 18.8 (CH2CH3), 10.4 (d, Jꢀ93, CH2CH3). IR:
/22.6
1.26 (broad, 3H, o-Me). 1H NMR (CD2Cl2, ꢂ
/
20 8C): d
7.46 (m, 3H, Ph), 7.35ꢁ7.32
(m, 6H, Ph), 6.92 (1H, Mes), 6.86 (1H, Mes), 6.75 (1H,
Mes), 6.63 (1H, Mes), 4.82 (dd, Jꢀ414, 13, 1H, PH),
7.61 (broad, 6H, Ph), 7.48ꢁ
/
/
/
2915, 2844, 2402, 1603, 1556, 1447, 1407, 1374, 1292,
1263, 1186, 1030, 946, 905, 848, 734, 612, 572, 552, 506,
457, 426, 408. 1H NMR (CD2Cl2, 21 8C): d 6.77 (broad,
/
3.38 (3H, o-Me), 2.50 (3H, o-Me), 2.25 (3H, p-Me), 2.23
(3H, p-Me), 1.85 (3H, o-Me), 1.20 (3H, o-Me). IR:
3436, 3025, 2919, 2731, 2413, 1601, 1431, 1378, 1096,
1025, 943, 902, 849, 743, 690, 620, 532.
8H, Mes) 2.6ꢁ
(broad, 5H, Et). The PH signals were not observed.
31P{1H} NMR (CD2Cl2, 21 8C): d ꢂ
39.9 (very broad,
JPtÃP 4500) ꢂ43.5 (very broad, JPtÃP 1310).
1H NMR (CD2Cl2, ꢂ
60 8C): Six different PH groups
were observed, confirmed by 1H{31P} NMR: d 6.82
(obscured by Mes, d, Jꢀ353, 1H, PH), 6.75 (obscured
by Mes, d, Jꢀ324, 1H, PH), 5.86 (apparent dd, Jꢀ395,
16, 1H, PH), 5.41 (apparent dd, Jꢀ400, 17, 1H, PH),
5.18 (apparent dd, Jꢀ354, 6, 1H, PH), 4.71 (apparent
dd, Jꢀ361, 8, 1H, PH). Additional signals: d 6.95ꢁ6.88
(m, Mes), 6.81ꢁ6.79 (m, Mes), 6.69ꢁ6.67 (m, Mes), 6.57
(Mes), 6.46 (Mes), 6.35ꢁ6.32 (m, Mes), 6.02ꢁ
Mes), 3.18ꢁ3.17 (m, Me), 3.12ꢁ
/2.0 (broad m, o-Me), 2.22 (p-Me), 1.02
/
:
/
/
:
/
4.12. cis-Pt(PMes2H)2(Me)(Cl) (6)
/
A light brown solution of Pt(cod)(Me)(Cl) (100 mg,
0.283 mmol) in CH2Cl2 (6 ml) was treated with PMes2H
(153 mg, 0.565 mmol). Petroleum ether (11 ml) was
layered on the solution and the mixture was cooled to ꢂ
20 8C to give 109 mg (49%) of white crystals in two
crops.
/
/
/
/
/
/
/
/
/
/
Anal. Calc. for C37H49ClP2Pt: C, 56.52; H, 6.28.
Found: C, 56.43; H, 6.25%. 31P{1H} NMR (CD2Cl2,
/
/5.99 (m,
/
/
3.11 (m, Me), 3.01 (Me),
21 8C): d ꢂ
1H NMR (CD2Cl2, 21 8C): d 6.74 (broad, Mes), 2.34
(broad, o-Me), 2.23 (p-Me), 0.60 (m, JPtÃP 50, PtÃ
Me). 1H NMR (CD2Cl2, ꢂ
70 8C): d 6.97ꢁ6.79 (m,
Mes), 6.72ꢁ6.67 (m, Mes), 6.59ꢁ6.58 (m, Mes), 6.51ꢁ
6.48 (m, Mes), 6.42 (Mes), 6.37 (apparent dd, Jꢀ449, 5,
1H, PH), 6.10ꢁ6.08 (m), 6.03 (Mes), 6.00 (Mes), 5.71 (d,
Jꢀ434, 1H, PH), 5.26 (apparent dd, Jꢀ403, 17, 1H,
PH), 5.13 (apparent dd, Jꢀ360, 5, 1H, PH), 4.56
(apparent dd, Jꢀ366, 7, 1H, PH), 3.26ꢁ3.20 (m, Me),
3.16 (Me), 3.00 (Me), 2.65ꢁ2.58 (m, Me), 2.52 (Me), 2.38
(Me), 2.22ꢁ2.18 (m, Me), 2.06ꢁ2.01 (m, Me), 1.95ꢁ1.93
(m, Me), 1.77 (Me), 1.66 (Me), 1.52 (Me), 1.47 (Me),
1.30 (Me), 0.86 (Me), 0.51ꢁ0.37 (PtÃ
Me). 13C{1H}
NMR (CD2Cl2, 21 8C): d 142.7 (m), 142.4 (very broad),
/
33.9 (JPtÃP
ꢀ
/
1492), ꢂ
/
45.1 (JPtÃP
ꢀ
/
4344).
2.89 (Me), 2.64 (Me), 2.59 (Me), 2.54 (Me), 2.50 (Me),
2.32ꢁ2.27 (m, Me), 2.23ꢁ2.18 (broad m, Me), 2.08ꢁ2.01
(broad m, Me), 1.99 (Me), 1.91 (Me), 1.88 (Me), 1.85
(Me), 1.80 (Me), 1.76 (Me), 1.66 (Me), 1.50ꢁ1.48 (m,
Me), 1.33ꢁ1.26 (m, Me), 1.16ꢁ1.12 (m, Me), 0.94 (Me),
0.83 (Me), 0.71ꢁ0.66 (m, PtÃEt), 0.59ꢁ0.54 (m, PtÃEt).
/
/
/
ꢀ
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
4.14. trans-Pt(PMes2H)2(Et)(I) (8)
/
/
/
cis-PtL2(Et)(I) (91 mg, 0.10 mmol) was dissolved in
approximately 1 ml of CDCl3 to give a yellow solution,
which was heated for 4 days at 40 8C and monitored by
1H NMR. When the isomerization to the trans com-
pound was complete, the contents of the NMR tube
were poured into a vial and petroleum ether was layered
/
/
/
/
/
/

2418
E.M. Pelczar et al. / Polyhedron 21 (2002) 2409ꢁ2419
/
on top. After 3 days, 72 mg (80%) of a bright yellow
precipitate formed. Recrystallization from CH2Cl2/ether
gave analytically pure light yellow crystals.
PH), 2.29 (12H, o-Me), 1.96 (6H, p-Me). The BH3
protons were not observed. 13C{1H} NMR (C6D6): d
143.0 (d, Jꢀ
/
9, Mes), 141.1 (d, Jꢀ/2, Mes), 130.8 (d,
Anal. Calc. for C38H51IP2Pt: C, 51.18; H, 5.76.
Found: C, 50.81; H, 5.80. 31P{1H} NMR (CDCl3): d
Jꢀ8, Mes), 123.4 (d, Jꢀ
/
/
50, Mes), 22.3 (d, Jꢀ
/
6, o-
Me), 21.2 (p-Me). IR: 3445, 3026, 2952, 2732, 2406,
2376, 2338, 2255, 2115, 1725, 1633, 1602, 1446, 1384,
1135, 1061, 1030, 967, 943, 893, 849, 756, 694, 626, 545.
1
ca. 3350). H NMR (CDCl3): d
ꢂ
/
39.5 (broad, JPtÃP
ꢀ
/
6.88 (8H, Mes), 2.48 (broad, Me), 2.30 (broad, Me), 1.10
(q, JHÃH 7, JPtÃH 114, 2H, CH2CH3), 0.68 (t,
JHÃH 7, JPtÃH 70, 3H, CH2CH3). The PH peaks
ꢀ
/
ꢀ
/
ꢀ
/
ꢀ
/
4.16. Crystallographic structural determination
were not observed. 13C{1H} NMR (CD2Cl2): d 143.1
(Mes), 140.9 (Mes), 130.6 (Mes), 124.1 (broad, Mes),
23.8 (broad, o-Me), 21.5 (p-Me), 17.6 (CH2CH3), 6.0
Crystal, data collection, and refinement parameters
are given in Table 3. A Siemens P4 diffractometer
equipped with a CCD detector was used. The structures
were solved using direct methods, completed by sub-
sequent difference Fourier syntheses and refined by full-
matrix least-squares procedures. All non-hydrogen
(JPtÃC
2728, 2395, 1604, 1556, 1443, 1408, 1378, 1289, 1259,
ꢀ671, CH2CH3). IR: 3440, 2953, 2906, 2846,
/
1200, 1063, 1028, 850, 802, 612, 553, 422.
1H NMR (CD2Cl2, 21 8C): d 6.96 (8H, Mes), 2.51
(24H, o-Mes), 2.42 (12H, p-Mes), 1.16 (q, JHÃH
JPtÃH 83, CH2CH3), 0.73 (t, JHÃH 7, JPtÃH
CH2CH3). 31P{1H} NMR (CD2Cl2, 21 8C): d ꢂ
ꢀ
/
7,
atoms were refined anisotropically. The PÃ
/
H hydrogens
ꢀ
/
ꢀ
/
ꢀ
/
70,
were located from the electron difference map and
allowed to refine isotropically. All software and sources
of the scattering factors are contained in the SHELXTL
(5.10) program library (G. Sheldrick, Siemens XRD,
Madison, WI). The figures were prepared using either
SHELXTL or ORTEP-3 for Windows [31].
/
39.0
1
(JPtÃP
ꢀ
/
3099). H NMR (CD2Cl2, ꢂ
/
70 8C): The four
1
1
expected PH signals were observed by H and H{31P}
NMR, but their low intensity and the presence of Mes
signals precluded detailed analysis of the AA?XX?
patterns. Instead we report the separation between the
two most intense lines of these patterns for a given
4.17. Cone angle calculations
resonance. d 7.35 (apparent d, Jꢀ
scured by Mes), 6.8 (apparent d, Jꢀ
ent d, Jꢀ375). Additional signals: d 7.15ꢁ
/
ca. 400), 7.1 (ob-
355), 6.15 (appar-
6.70 (broad
/
Cone angles were calculated using the program
STERIC [21], as previously reported [32]. Hydrogen
/
/
m, Mes), 3.23 (Me), 3.22 (Me), 3.17 (Me), 3.03 (Me),
2.62 (Me), 2.34 (Me), 2.29 (Me), 2.27 (Me), 2.08 (Me),
2.04 (Me), 1.87 (Me), 1.75 (Me), 1.67 (Me), 1.51 (Me),
atoms, as placed in the crystallographic determination,
˚
H
were fixed at a CÃ
/
H distance of 1.1 A, and a PÃ
/
˚
distance of 1.42 A [33]. Calculations on 5×
showed that changing the PÃH distance from 1.22 to
1.50 A had minimal effect (change from 1478 to 1498) on
P bond distances were fixed at
/
2CH2Cl2
1.50 (Me), 1.16ꢁ
0.60 (broad m, Me), 0.45 (m, PtÃ
1H NMR (C6D5Cl, 21 8C): d 6.72 (Mes), 2.52 (o-Me),
2.07 (p-Me), 1.35 (m, PtÃEt), 0.84 (m, PtÃEt). The PH
resonances were not observed. 31P{1H} NMR (C6D5Cl,
21 8C): d ꢂ36.8 (very broad, JPtÃP
ca. 3300). 1H
NMR (C6D5Cl, 80 8C): d 7.24 (apparent d, Jꢀ384,
JPtÃH 26, perhaps the most intense two peaks of an
AA?XX? pattern), 6.72 (Mes), 2.51 (o-Me), 2.08 (p-Me),
1.33 (q, JHH 8, JPtÃH 84, CH2CH3), 0.84 (t, JHH 8,
JPtÃH 72, CH2CH3).
/
1.11 (m, Me), 0.89ꢁ
/
0.87 (m, Me), 0.80ꢁ
/
/
˚
/
Et), 0.29 (m, PtÃ
/Et).
the cone angle. The MÃ
/
˚
2.28 A [22]. The CPK van der Waals radii set was used
for all cone angle calculations.
/
/
/
ꢀ
/
/
ꢀ
/
5. Supplementary material
ꢀ
/
ꢀ
/
ꢀ
/
Crystallographic data for the structures reported in
this paper have been deposited with the Cambridge
ꢀ
/
Crystallographic Data Centre, CCDC Nos. 181084ꢁ
/
4.15. PMes2H×
/
BH3 (9)
181086 and 181088ꢁ181089. Copies of this information
may be obtained free of charge from The Director,
CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK
/
A clear solution of PMes2H (300 mg, 1.11 mmol) in
THF (6 ml) was cooled to 0 8C and treated with 834 ml
(fax: ꢄ44-1223-336033; e-mail: deposit@ccdc.cam.ac.uk
/
of BH3×/SMe2 (1.67 mmol). The solution was warmed to
or www: http://www.ccdc.cam.ac.uk).
room temperature with stirring. The solvent was re-
moved under vacuum to give a white solid, which was
recrystallized from petroleum ether at 0 8C to give large
white crystals (297 mg, 95%, in four crops). Anal. Calc.
for C18H26BP: C, 76.08; H, 9.22. Found: C, 75.73; H,
Acknowledgements
We thank the NSF Career Program, DuPont, and
Union Carbide (Innovation Recognition Award) for
support, and the Department of Education for a
GAANN fellowship for M.A.Z. The University of
9.37%. 31P{1H} NMR (C6D6): d ꢂ
NMR (C6D6): d ꢂ27.3 (broad d, JPH
(C6D6): d 6.53 (d, Jꢀ
/
27.3 (broad). 31P
1
383). H NMR
/
ꢀ
/
/
3, 4H, Mes), 6.42 (dq, Jꢀ382, 8,
/

E.M. Pelczar et al. / Polyhedron 21 (2002) 2409ꢁ
/2419
2419
[10] P. Budzelaar, gNMR, V3.6.5, Cherwell Scientific Publishing,
Oxford, 1996.
Delaware acknowledges the NSF (Grant CHE-9628768)
for their support of the purchase of the CCD-based
diffractometer.
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