Synthesis and reactivity of new κ2-[P,N]Pt(II) complexes of diisopropylphosphino-substituted 2-dimethylaminoindene

Article abstract of DOI:10.1021/om049034w

Treatment of 1-PⁱPr₂-2-NMe₂-indene (la[H]) with either czs/trans-(SMe₂)₂PtCl₂ or PtCl₂ provided (κ²2-P,N-2-NMe₂-3-P ⁱPr₂-indene)PtCl₂ (2) in 84% and 55% yield, respectively, while the reaction of 1a[H] with (η⁴-COD)PtClMe afforded (κ²-P,N-2-NMe₂-3-PⁱPr ₂-indene)PtClMe (3) in 91% yield. Whereas in the formation of 2 and 3 the ligand precursor 1a[H] undergoes a rearrangement to give a coordinated 2-NMe₂-3-PⁱPr₂-indene (1b[H]) ligand, 1a[H] reacted cleanly with 0.5 equiv of [(μ-SMe₂)PtMe₂] ₂ to give (κ²-P,N-1a[H])PtMe₂ (4a) in 97% yield. The isomerization of 4a to (κ²-P,N-1b[H])PtMe ₂ (4b) in a THF/ⁱPrOH mixture is rapid and allowed for the isolation of 4b in 99% yield. Heating of 4a in CH₂Cl₂ resulted in the quantitative formation of 3, while the thermolysis of 4a in toluene in the presence of SMe₂ afforded 5, the apparent product of intramolecular C-H activation of an NMe group. The reactivity of 4a with a variety of other two-electron donors, as well as E-H-containing substrates (E = main group fragment), is reported. Although NMR spectroscopic evidence indicated the formation of an intermediate of the type (κ²-P,N-1[H]) Pt(SnPh₃)(Me), as well as Ph₆Sn₂, in the reaction of 4a with 10 equiv of Ph₃SnH, negligible conversion of Ph₃SnH to Ph₆Sn₂ was obtained when employing 1 mol % 4a as a catalyst. Single-crystal X-ray diffraction data for 2 and 5 are reported.

Full text of DOI:10.1021/om049034w

Organometallics 2005, 24, 1959-1965
1959
Synthesis and Reactivity of New K2-[P,N]Pt(II)
Complexes of Diisopropylphosphino-Substituted
2-Dimethylaminoindene
Bradley M. Wile,† Robert McDonald,‡ Michael J. Ferguson,‡ and
Mark Stradiotto*,†
Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4J3, and
X-Ray Crystallography Laboratory, Department of Chemistry, University of Alberta,
Edmonton, Alberta, Canada T6G 2G2
Received December 7, 2004
Treatment of 1-PiPr2-2-NMe2-indene (1a[H]) with either cis/trans-(SMe2)2PtCl2 or PtCl2
provided (κ2-P,N-2-NMe2-3-PiPr2-indene)PtCl2 (2) in 84% and 55% yield, respectively, while
the reaction of 1a[H] with (η4-COD)PtClMe afforded (κ2-P,N-2-NMe2-3-PiPr2-indene)PtClMe
(3) in 91% yield. Whereas in the formation of 2 and 3 the ligand precursor 1a[H] undergoes
a rearrangement to give a coordinated 2-NMe2-3-PiPr2-indene (1b[H]) ligand, 1a[H] reacted
cleanly with 0.5 equiv of [(µ-SMe2)PtMe2]2 to give (κ2-P,N-1a[H])PtMe2 (4a) in 97% yield.
The isomerization of 4a to (κ2-P,N-1b[H])PtMe2 (4b) in a THF/iPrOH mixture is rapid and
allowed for the isolation of 4b in 99% yield. Heating of 4a in CH2Cl2 resulted in the
quantitative formation of 3, while the thermolysis of 4a in toluene in the presence of SMe2
afforded 5, the apparent product of intramolecular C-H activation of an NMe group. The
reactivity of 4a with a variety of other two-electron donors, as well as E-H-containing
substrates (E ) main group fragment), is reported. Although NMR spectroscopic evidence
indicated the formation of an intermediate of the type (κ2-P,N-1[H])Pt(SnPh3)(Me), as well
as Ph6Sn2, in the reaction of 4a with 10 equiv of Ph3SnH, negligible conversion of Ph3SnH
to Ph6Sn2 was obtained when employing 1 mol % 4a as a catalyst. Single-crystal X-ray
diffraction data for 2 and 5 are reported.
Introduction
and the counteranion or coordinating solvent molecules
for the metal active site can result in diminished
reactivity. In the context of Rh(I) we have demonstrated
that 1-PiPr2-2-NMe2-indene (1a[H]) and 2-NMe2-3-
PiPr2-indene (1b[H]) serve as precursors to (κ2-P,N-1)-
Rh(η4-COD), the first formally zwitterionic analogue of
ubiquitous [κ2-P,N-Rh(η4-COD)]+X- cationic catalysts,
which is effective in mediating the dehydrogenative
cross-coupling of C-H and Si-H units.2a Notably, the
10π indenide backbone in (κ2-P,N-1)Rh(η4-COD) func-
tions as a sequestered anionic charge reservoir, rather
than as a site for metal binding.2a
In expanding our exploration of the coordination
chemistry and reactivity behavior of metal complexes
supported by 1[H] and related ligands, we naturally
became interested in the study of platinum complexes,
owing to their well-established propensity for E-H bond
activation under homogeneous reaction conditions.3 A
survey of the literature reveals that most of the Pt(II)
complexes that are able to effect intermolecular C-H
bond activation are cationic and feature a bidentate N,N
ancillary support.4 However, the viability of intermo-
lecular C-H activation by neutral Pt(II) complexes5,6
and those featuring P,P ligands6,7 has been demon-
strated.3b As such, it has been suggested that the ability
of the aforementioned 16-electron, four-coordinate [κ2-
N,N-Pt(R)(L)]+X- complexes to activate C-H bonds may
With the goal of developing new and synthetically
useful stoichiometric and/or catalytic reaction chemistry
based on the metal-mediated activation of E-H bonds
(E ) main group element),1 we have recently initiated
a research program focused in part on developing
charge-neutral alternatives to traditional cationic late
metal complexes.2 Although such cationic species often
possess desirable reactivity properties, the inherently
polar nature of discrete salts can necessitate the use of
high-polarity reaction media. Under such conditions,
unfavorable competition between substrate molecules
* To whom correspondence should be addressed. Fax: 1-902-494-
1310. Tel:
1-902-494-7190. E-mail:
mark.stradiotto@dal.ca.
† Dalhousie University.
‡ University of Alberta.
(1) For selected reviews on E-H activation, see: (a) Schneider, J.
J. Angew. Chem., Int. Ed. Engl. 1996, 35, 1068. (b) Shilov, A. E.;
Shul’pin, G. B. Chem. Rev. 1997, 97, 2879. (c) Gauvin, F.; Harrod, J.
F.; Woo, H. G. Adv. Inorg. Chem. 1998, 42, 363. (d) Dyker, G. Angew.
Chem., Int. Ed. 1999, 38, 1698. (e) Reichl, J. A.; Berry, D. H. Adv.
Inorg. Chem. 1999, 43, 197. (f) Harrod, J. F. Coord. Chem. Rev. 2000,
206-207, 493. (g) Jia, C.; Kitamura, T.; Fujiwara, Y. Acc. Chem. Res.
2001, 34, 633. (h) Ritleng, V.; Sirlin, C.; Pfeffer, M. Chem. Rev. 2002,
102, 1731. (i) Ishiyama, T.; Miyaura, N. J. Organomet. Chem. 2003,
680, 3. (j) Alonso, F.; Beletskaya, I. P.; Yus, M. Chem. Rev. 2004, 104,
3079.
(2) (a) Stradiotto, M.; Cipot, J.; McDonald, R. J. Am. Chem. Soc.
2003, 125, 5618. (b) Cipot, J.; Wechsler, D.; Stradiotto, M.; McDonald,
R.; Ferguson M. J. Organometallics 2003, 22, 5185. (c) Wechsler, D.;
McDonald, R.; Ferguson, M. J.; Stradiotto, M. Chem. Commun. 2004,
2446. (d) Stradiotto, M.; McGlinchey, M. J. Coord. Chem. Rev. 2001,
219-221, 311.
(3) (a) Clarke, M. L. Polyhedron 2001, 20, 151. (b) Fekl, U.; Goldberg,
K. I. Adv. Inorg. Chem. 2003, 54, 259.
10.1021/om049034w CCC: $30.25 © 2005 American Chemical Society
Publication on Web 03/04/2005

1960 Organometallics, Vol. 24, No. 8, 2005
Wile et al.
Scheme 1a
be attributed more to their capacity to generate unsat-
urated, 14-electron three-coordinate [κ2-N,N-Pt(R)]+X-
intermediates upon loss of a neutral, two-electron donor
(L) rather than to the formally cationic nature of the
Pt(II) center.3b Given that [L2Pt(R)]+X- species are
prone to attack by polar solvent molecules and/or the
counteranion, we set out to develop alternative classes
of reactive Pt(II) complexes that would provide access
to neutral, unsaturated LPtR2 reactive intermediates
in low-polarity solvents (e.g., hydrocarbons). Chelating,
mixed-donor P,N-ligands are poised to exhibit hemi-
labile behavior when coordinated to Pt(II),8 with the
softer P-donor serving to anchor the ligand to the metal
and the harder N-donor temporarily occupying a metal
coordination site in the absence of substrate molecules.9
For (κ2-P,N-1[H])PtX2 systems in particular, the forma-
tion of unsaturated (κ1-P,N-1[H])PtX2 intermediates
becomes increasingly favorable since the uncoordinated
dimethylamino group is stabilized by entering into
conjugation with the π-system of the indene backbone.2
Bidentate P,N-ligands such as 1[H] are also advanta-
geous in that they should stabilize both low- and high-
oxidation state platinum species formed in the course
of E-H bond activation processes. Despite the well-
established ability of P,N-ligands to confer desirable
reactivity properties to a variety of platinum-group
metal fragments,10 the application of such a ligation
strategy to the development of Pt(II) complexes for E-H
and E-C bond activation has received relatively little
attention.11-13 Herein we report on the synthesis and
characterization of new Pt(II) complexes featuring 1[H],
including a preliminary survey of the E-H bond activa-
tion capabilities and other reactivity properties of (κ2-
P,N-1a[H])PtMe2.
a Reagents and conditions: (i) cis/trans-(SMe2)2PtCl2 or
PtCl2; (ii) (η4-COD)PtClMe; (iii) 0.5 [(µ-SMe2)PtMe2]2; (iv) (a)
22 °C, 15 days; (b) 50 °C, 45 h; (c) Et3N, 22 °C, 7 days; or (d)
iPrOH, 22 °C, 10 min.
Results and Discussion
Synthesis and Characterization of (K2-P,N)PtX2
Complexes. Target complexes of the type (κ2-P,N-1[H])-
PtX2 were prepared as outlined in Scheme 1. Treatment
of 1a[H] with either cis/trans-(SMe2)2PtCl2 or PtCl2
affords (κ2-P,N-1b[H])PtCl2 (2) in 84% and 55% yield,
respectively. Similarly, the reaction of 1a[H] with (η4-
COD)PtClMe provides (κ2-P,N-1b[H])PtClMe (3) in 91%
isolated yield. In the formation of both 2 and 3, the
ligand precursor 1a[H] undergoes a structural re-
arrangement that places the PiPr2 fragment at the
vinylic (C3) position on the indene backbone, resulting
in the exclusive formation of (κ2-P,N-1b[H])PtX2 species.
In contrast, 1a[H] reacts cleanly with 0.5 equiv of [(µ-
SMe2)PtMe2]2 at 22 °C over 3 h to give pure (κ2-P,N-
1a[H])PtMe2 (4a), which was isolated in 97% yield. The
isomerization of the allylic isomer 4a to (κ2-P,N-1b[H])-
PtMe2 (4b) does proceed slowly in the solid and in
solution; after 15 days at 22 °C in toluene, over 95%
conversion to 4b is observed (based on 1H and 31P NMR
data). Similar results are obtained either by heating
toluene solutions of 4a (50 °C, 45 h) or by the addition
of 10 equiv of NEt3 (22 °C, 7 days). Interestingly, the
clean rearrangement of 4a to 4b in a THF/iPrOH
mixture is rapid (22 °C, 10 min), allowing for the
isolation of pure 4b in nearly quantitative yield. The
solvent-dependent interconversion of allylic and vinylic
(4) For some recent examples of intermolecular C-H activation
involving N2Pt+ complexes, see: (a) Johansson, L.; Ryan, O. B.;
Rømming, C.; Tilset, M. J. Am. Chem. Soc. 2001, 123, 6579. (b)
Vedernikov, A. N.; Caulton, K. G. Angew. Chem., Int. Ed. 2002, 41,
4102. (c) Heyduk, A. F.; Labinger, J. A.; Bercaw, J. E. J. Am. Chem.
Soc. 2003, 125, 6366. (d) Song, D.; Wang, S. Organometallics 2003,
22, 2187. (e) Song, D.; Jia, W. L.; Wang, S. Organometallics 2004, 23,
1194. (f) Ong, C. M.; Burchell, T. J.; Puddephatt, R. J. Organometallics
2004, 23, 1493. (g) Heyduk, A. F.; Driver, T. G.; Labinger, J. A.; Bercaw,
J. E. J. Am. Chem. Soc. 2004, 126, 15034.
(5) For some recent examples of intermolecular C-H activation
involving NnPt complexes, see: (a) Fekl, U.; Goldberg, K. I. J. Am.
Chem. Soc. 2002, 124, 6804. (b) Harkins, S. B.; Peters, J. C. Organo-
metallics 2002, 21, 1753. (c) Fekl, U.; Kaminsky, W.; Goldberg, K. I.
J. Am. Chem. Soc. 2003, 125, 15286. (d) Jensen, M. P.; Wick, D. D.;
Reinartz, S.; White, P. S.; Templeton, J. L.; Goldberg, K. I. J. Am.
Chem. Soc. 2003, 125, 8614. (e) Iverson, C. N.; Carter, C. A. G.; Baker,
R. T.; Scollard, J. D.; Labinger, J. A.; Bercaw, J. E. J. Am. Chem. Soc.
2003, 125, 12674.
(6) (a) Thomas, J. C.; Peters, J. C. J. Am. Chem. Soc. 2001, 123,
5100. (b) Thomas, J. C.; Peters, J. C. J. Am. Chem. Soc. 2003, 125,
8870.
(7) Konze, W. V.; Scott, B. L.; Kubas, G. J. J. Am. Chem. Soc. 2002,
124, 12550.
(8) Slone, C. S.; Weinberger, D. A.; Mirkin, C. A. Prog. Inorg. Chem.
1999, 48, 233.
(9) Pearson, R. G. Inorg. Chem. 1988, 27, 734.
(12) The reactivity of Si-H and Sn-H bonds with PNPt complexes
has been explored by Schubert and co-workers: (a) Pfeiffer, J.;
Schubert, U. Organometallics 1999, 18, 3245. (b) Pfeiffer, J.; Kickelbick,
G.; Schubert, U. Organometallics 2000, 19, 62, and references therein.
(c) Sto¨hr, F.; Sturmayr, D.; Schubert, U. Chem. Commun. 2002, 2222.
(d) Schubert, U.; Pfeiffer, J.; Sto¨hr, F.; Sturmayr, D.; Thompson, S. J.
Organomet. Chem. 2002, 646, 53. (e) Thompson, S. M.; Sto¨hr, F.;
Sturmayr, D.; Kickelbick, G.; Schubert, U. J. Organomet. Chem. 2003,
686, 183. (f) Thompson, S. M.; Schubert, U. Inorg. Chim. Acta 2003,
350, 329.
(10) (a) Helmchen, G.; Pfaltz, A. Acc. Chem. Res. 2000, 33, 336. (b)
Gavrilov, K. N.; Polosukhin, A. I. Russ. Chem. Rev. 2000, 69, 661. (c)
Chelucci, G.; Orru`, G.; Pinna, G. A. Tetrahedron 2003, 59, 9471.
(11) For some examples of C-H and/or C-C activation involving
PNPt complexes, see: (a) Gandelman, M.; Vigalok, A.; Shimon, L. J.
W.; Milstein, D. Organometallics 1997, 16, 3981. (b) Mu¨ller, C.; Iverson,
C. N.; Lachicotte, R. J.; Jones, W. D. J. Am. Chem. Soc. 2001, 123,
9718. (c) Mu¨ller, C.; Lachicotte, R. J.; Jones, W. D. Organometallics
2002, 21, 1118. (d) Kataoka, Y.; Nakamura, T.; Tani, K. Chem. Lett.
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Rozenberg, H.; Ben-David, Y.; Milstein, D. Chem. Eur. J. 2004, 10,
4673.
(13) For NMR evidence of hemilability in a PNPt(II) complex, see:
Tsutsuminai, S.; Komine, N.; Hirano, M.; Komiya, S. Organometallics
2003, 22, 4238.

Reactivity of New κ2-[P,N]Pt(II) Complexes
Organometallics, Vol. 24, No. 8, 2005 1961
Table 1. Crystallographic Data for 2 and 5
2
5
empirical formula
fw
cryst dimens
temp (K)
cryst syst
space group
a (Å)
C
17H26Cl2NPPt
C20H34NPPtS
546.60
541.35
0.43 × 0.16 × 0.12 0.36 × 0.20 × 0.09
193(2)
193 (2)
monoclinic
P21/n
orthorhombic
P212121
7.6580 (3)
15.2323 (6)
16.8331 (7)
90
10.388 (1)
21.813 (2)
10.570 (1)
114.546 (2)
2178.6 (4)
4
b (Å)
c (Å)
â (deg)
V (Å3)
1963.6(1)
4
Z
F
calcd (g cm-3
)
1.831
1.666
µ (mm-1
2θ limit (deg)
)
7.496
6.612
52.72
52.82
-9 e h e 9
-19 e k e 18
-21 e l e 20
-12 e h e 12
-27 e k e 27
-13 e l e 13
16 628
Figure 1. ORTEP diagram for 2, shown with 50% dis-
placement ellipsoids and with the atomic numbering
scheme indicated. Selected hydrogen atoms have been
omitted for clarity. Selected bond lengths (Å) for 2: Pt-
Cl1 2.3753(8); Pt-Cl2 2.2978(8); Pt-P 2.2006(7); Pt-N
2.091(2); N-C2 1.472(4); P-C3 1.809(3); C1-C2 1.505(4);
C2-C3 1.332(4).
total no. of data collected 12 801
no. of indep reflns
no. of obsd reflns
Rint
4011
3968
0.0202
Multiscan
(SADABS)
0.4666-0.1409
4011/0/200
4466
3792
0.0347
Multiscan
(SADABS)
0.5876-0.1994
4466/0/219
abs corr
range of transmn
no. of data/restraints/
params
R1 [Fo2 g 2σ(Fo2)]
wR2 [Fo2 g -3σ( Fo2)]
goodness-of-fit
0.0155
0.0275
indenylphosphine isomers is an established phe-
nomenon.2d
0.0381
0.0672
1.085
1.076
largest peak, hole (e Å-3
)
1.433, -0.459
1.923, -0.331
The structures of 2, 3, 4a, and 4b depicted in Scheme
1 are supported by 1D- and 2D-NMR spectroscopic data.
The 31P{1H} NMR spectrum for each complex is com-
prised of a singlet with accompanying platinum satel-
lites. In the case of 3, the magnitude of this coupling
constant (1JPtP ) 4487 Hz) confirms the cis-disposition
of the phosphine and methyl fragments. The alternative
isomer featuring a methyl group trans to phosphorus
initial studies in light of the established propensity of
Pt-CH3 linkages to react with E-H bonds to yield Pt-E
and CH4.3b,4-7,11,12
Thermolysis of 4a. Complex 4a is stable in benzene,
toluene, or THF at 22 °C, with the exception of the
aforementioned slow conversion to 4b. However, ther-
molysis (70 °C) of 4a in each of these solvents generated
a complex mixture of phosphorus-containing complexes,
including 4a (δ 31P ) 27.6), 4b (δ 31P ) 39.2), and a
1
would be expected to give rise to a much lower JPtP
value, given the stronger trans-influence of the methyl
1
substituent, relative to chloride;12b indeed, the JPtP in
new platinum-containing species (δ 31P ) 19.0, 1JPtP
≈
4b (2039 Hz) is diminished relative to 3. The Cs
1
symmetry of 2, 3, and 4b is evident in the H and 13C
3000 Hz); this new complex represents the major
product after 48 h. We have thus far been unsuccessful
in isolating this thermolysis product. However, the
observation that the same thermolysis product appears
to form in benzene, toluene, and THF suggests that this
product might arise due to an intramolecular bond
activation process (vide infra), rather than as a result
of an intermolecular reaction involving the solvent.
Although 4a is stable in CH2Cl2 at 22 °C, heating in
this solvent at 50 °C for 18 h cleanly produces (κ2-P,N-
1b[H])PtClMe, 3 (Scheme 2). In keeping with estab-
lished reactivity trends observed for (κ2-P,N)PtMe2
species,15 CHCl3 proved more reactive than CH2Cl2
toward 4a, producing a complex mixture of products
including 3. Similarly, dissolution of 4a in CH3CN (or
treatment of this complex with 1 equiv of CH3CN in
toluene) either at 22 °C or with heating (75 °C for 72 h)
resulted in the slow consumption of 4a (based on 31P
NMR data) without the formation of detectable phos-
phorus-containing product(s) or precipitated solids.
NMR data for these complexes. Conversely, the 1H and
13C NMR spectra of 4a clearly indicate a lack of mirror-
plane symmetry, with both vinylic and allylic C-H units
on the indene backbone, as well as pairs of nonequiva-
lent iPr and Me fragments, being clearly discernible. The
structure of 2 was also confirmed on the basis of data
obtained from a single-crystal X-ray diffraction study.
The crystal structure of 2 is presented in Figure 1, and
relevant crystallographic parameters are collected in
Table 1. The platinum center in 2 deviates only mod-
estly from ideal square-planar geometry (∑angles at Pt
≈
360°), with the Pt-Cl1 distance trans to the P-donor
(2.3753(8) Å) being significantly longer than the corre-
sponding Pt-Cl2 distance trans to N (2.2978(8) Å), in
keeping with the greater trans-influence of the P-donor
fragment. Although we were unable to identify a crys-
tallographically characterized (κ2-P,N)PtCl2 from the
literature, the interatomic distances in 2 can be com-
pared with those found in other Pt(II) complexes.11e,12e,13,14
Having established viable synthetic routes to (κ2-P,N-
1[H])PtX2 complexes, a preliminary reactivity survey
involving 4a (containing <5% 4b) was undertaken. The
(κ2-P,N-1a[H])PtMe2 complex (4a) was selected for these
1
Given the complexity of the H NMR spectrum of the
crude reaction mixture, and the fact that we have not
been able to isolate pure materials from this mixture,
we are unable to conclusively identify the platinum-
containing product(s) of this reaction.
(14) (a) Rashidi, M.; Jennings, M. C.; Puddephatt, R. J. Organome-
tallics 2003, 22, 2612. (b) Jamali, S.; Rashidi, M.; Jennings, M. C.;
Puddephatt, R. J. Dalton Trans. 2003, 2313.
(15) Sto¨hr, F.; Sturmayr, D.; Kickelbick, G.; Schubert, U. Eur. J.
Inorg. Chem. 2002, 2305.

1962 Organometallics, Vol. 24, No. 8, 2005
Wile et al.
Scheme 2a
Figure 2. ORTEP diagram for 5, shown with 50% dis-
placement ellipsoids and with the atomic numbering
scheme indicated. Selected hydrogen atoms have been
omitted for clarity. Selected bond lengths (Å) for 5: Pt-S
2.365(1); Pt-C8 2.039(4); Pt-C16 2.094(4); Pt-P 2.303-
(1); N-C2 1.326(5); N-C8 1.461(5); N-C9 1.453(5); P-C3
1.786(4); C1-C2 1.516(6); C2-C3 1.395(5).
a Reagents and conditions: (i) CH2Cl2, 50 °C, 18 h; (ii) (a)
CHCl3; (b) 4-(dimethylamino)pyridine, 75 °C, 72 h; or (c)
CH3CN, 75 °C, 72 h; (iii) 10 equiv of PPh3; (iv) SMe2, 70 °C,
20 h.
Reactivity of 4a with L-Donors. In an attempt to
assess the binding strength of the P,N-chelate in 4a,
this complex was exposed to a variety of two-electron
donors (L) in toluene, and the progress of the reaction
was monitored by use of 31P NMR spectroscopic tech-
niques. While no reaction was observed between 4a and
1 equiv of 4-(dimethylamino)pyridine (DMAP) at 22 °C
over 24 h, heating of this mixture at 75 °C resulted in
the generation of multiple phosphorus-containing prod-
ucts. Conversely, treatment of 4a with 1 equiv of PPh3
at 22 °C generated a mixture containing only (PPh3)2-
PtMe2,16 1a,b[H], and unreacted 4a; upon addition of
10 equiv of PPh3, only (PPh3)2PtMe2, 1a,b[H], and PPh3
were detected. These observations suggest that putative
(κ1-P,N-1[H])Pt(PPh3)Me2 intermediates are more reac-
tive than 4a toward ligand substitution by PPh3, a
situation that may be attributed to steric crowding in
such intermediates. Alternatively, a toluene solution of
4a was treated with 2.5 equiv of SMe2 at 22 °C. The
usual slow transformation of 4a into 4b was observed
after several days, accompanied by the appearance of a
single new platinum-containing product (δ 31P ) 16.8
ppm, 1JPtP ) 2006 Hz); after 15 days, this new complex
(5) represented the major species present in solution.
When the reaction was instead conducted at 70 °C,
complete conversion was achieved after 20 h, allowing
for the isolation of pure 5 as a brown solid in 61% yield.
Although 1H and 13C NMR spectroscopic data confirmed
the presence of a SMe2 ligand in 5, the other spectral
features observed clearly indicated that this complex
was not a simple adduct of the type (κ1-P,N-1[H])Pt-
(SMe2)Me2. The connectivity in 5 was ultimately eluci-
dated on the basis of data obtained from a single-crystal
X-ray diffraction experiment; the structure of 5 is
presented in Figure 2, and relevant crystallographic
parameters are collected in Table 1. The platinum
center in 5 exhibits typical square-planar geometry
(∑angles at Pt ≈ 360°) and is ligated by N-CH2 and CH3
fragments, as well as cis-disposed P- and S-donors. The
planarity at nitrogen (∑angles at N ≈ 360°) and the con-
tracted N-C2 distance (1.326(5) Å) relative to both the
other N-C distances in 5 (1.461(5), 1.453(5) Å) and the
N-C2 distance in 2 (1.472(4) Å) indicate that the
nitrogen fragment in 5 is in conjugation with the indenyl
framework. Although details of the mechanistic path-
way leading to 5 are unknown, this complex can be
viewed as arising from an intramolecular C-H activa-
tion process involving one of the NMe groups in a three-
coordinate intermediate of the type (κ1-P,N-1[H])PtMe2,
with the loss of CH4 and coordination of SMe2 yielding
the observed product. The activation of NMe C-H bonds
has been observed for a range of transition metal
fragments;17 the structural features found in 5 are
comparable to those observed in a related cyclometa-
lated platinum complex.17a
Reactivity of 4a with E-H Bonds. In an attempt
to survey the intermolecular E-H bond activation
capabilities of 4a, the reactivity of this complex with a
variety of main group substrates (in C6D6 or toluene)
was examined. Treatment of 4a with either dihydrogen
(1 atm) or pinacolborane (1 equiv) resulted in no
observable reaction (1H and 31P NMR), even after
heating for 3 days at 50 °C. In contrast, PhCtCH, Ph3-
SiH, Ph2SiH2, PhSiH3, and Et3SiH were each observed
to react with 4a to some extent at 22 °C. However,
multiple phosphorus-containing products were gener-
ated in each case, regardless of the subtrate:4a ratio
(1:1, 2:1, or 10:1) or the reaction temperature (22-75
°C) employed, and we have thus far been unable to
unequivocally characterize any of the products from
these reaction mixtures. In monitoring the reaction of
1
4a with the aforementioned silanes by use of H NMR
techniques, no Pt-H species were detected, and Pt-
Me resonances persisted throughout the course of each
reaction. Complex reactivity between (κ2-P,N)PtMe2
complexes and organosilanes has been observed pre-
viously.12e
Braunstein,18 Schubert,12f and others18c have demon-
strated that complexes of the heavier group 10 metals
are capable of mediating the dehydrogenative dimer-
(17) For the crystallographic characterization of NMe C-H activa-
tion products, see: (a) Fantasia, S.; Manaserro, M.; Pasini, A. Inorg.
Chem. Commun. 2004, 7, 97. (b) Mu, Y.; Piers, W. E.; MacQuarrie, D.
C.; Zaworotko, M. J.; Young, V. G., Jr. Organometallics 1996, 15, 2720.
(c) Mauthner, K.; Slugovc, C.; Mereiter, K.; Schmid, R.; Kirchner, K.
Organometallics 1997, 16, 1956. (d) Liu, G.; Beetstra, D. J.; Meetsma,
A.; Hessen, B. Organometallics 2004, 23, 3914. (e) Clot, E.; Chen, J.;
Lee, D.-H.; Sung, S. Y.; Appelhans, L. N.; Faller, J. W.; Crabtree, R.
H.; Eisenstein, O. J. Am. Chem. Soc. 2004, 126, 8795.
(18) (a) Braunstein, P.; Morise, X.; Blin, J. Chem. Commun. 1995,
1455. (b) Braunstein, P.; Morise, X. Organometallics 1998, 17, 540. (c)
Braunstein, P.; Morise, X. Chem. Rev. 2000, 100, 3541, and references
therein.
(16) Goodfellow, R. J.; Hardy, M. J.; Taylor, B. F. J. Chem. Soc.,
Dalton Trans. 1973, 2450.

Reactivity of New κ2-[P,N]Pt(II) Complexes
Organometallics, Vol. 24, No. 8, 2005 1963
Scheme 3. Proposed Pathway for the Reaction of
4a with 10 Equiv of Ph3SnH in C6D6
ization of Ph3SnH to yield Ph6Sn2. In this context, the
reaction of 4a with Ph3SnH (C6D6, 22 °C) was examined.
Given the known light-sensitivity of Sn-H bonds,19 the
photostability of C6D6 solutions of Ph3SnH in the
absence of 4a was evaluated (1H and 119Sn NMR).
Solutions stored in the dark for 20 days exhibited NMR
signals attributable only to Ph3SnH with no observable
H/D exchange involving the Sn-H fragment, and upon
exposure to ambient light for 3.5 h, only a trace of Ph6-
Sn2 was detected (119Sn NMR).12f The reaction of 4a with
Ph3SnH (1:1 ratio) generated a mixture of phosphorus-
containing products that gave rise to 31P NMR reso-
nances at 43.6 (∼5%), 41.0 (∼5%), and 27.6 (4a, ∼90%)
ppm; the intensity ratio of these signals did not change
significantly over 24 h. In contrast, reactions employing
10 equiv of Ph3SnH resulted in the consumption of 4a
after 2 min, accompanied by the clean formation of a
single phosphorus-containing product (6) at 43.6 ppm
relative magnitude of the observed JPSn coupling,22 we
were unable to unambiguously identify an accompany-
ing 31P-coupled signal in the 119Sn NMR spectrum that
could be assigned to 7. We have thus far been unable
to obtain purified samples of 7 for further characteriza-
tion. The generation of 7 underscores the possibility that
the observed conversion of Ph3SnH is mediated by ill-
defined Pt species (possibly metallic or colloidal), rather
than a discrete complex featuring 1[H].
1
(singlet with Pt satellites, JPtP ) 2601 Hz). While the
presence of unreacted Ph3SnH and dihydrogen (4.46
ppm) was evident in the 1H NMR spectrum of the
reaction mixture after 5 min, neither well-resolved Pt-
Me signals nor low-frequency resonances associated
with Pt-H fragments were observed. Analysis of the
reaction mixture after 20 min by use of 119Sn NMR
techniques indicated the presence of Ph3SnH (-163.2
ppm, ∼45%), Ph3SnMe (-90.2 ppm, ∼20%), Ph6Sn2
(-141.6 ppm, ∼20%), and an unidentified complex
(-125.9 ppm, ∼15%, possibly Ph4Sn);12f,20 the Ph3SnH
was ultimately consumed after 4 h, with the product
mixture exhibiting 119Sn NMR signals at -228.9
(∼15%),21 -141.6 (Ph6Sn2, ∼40%), -125.8 (∼30%), and
-90.2 (Ph3SnMe, ∼15%) ppm. Notably, no platinum-
coupled 119Sn NMR resonances were observed through-
out the course of this reaction. The 31P NMR spectrum
of the product mixture after 4 h revealed the presence
of one dominant phosphorus-containing species at 18.9
ppm (singlet with satellites, J ) 133 Hz), accompanied
by low-intensity resonances at 60.2 and 43.6 ppm.
Collectively, these spectroscopic observations are con-
sistent with the reaction pathway tentatively proposed
in Scheme 3, in which 4a initially reacts with Ph3SnH
to give an unobserved (κ2-P,N-1[H])Pt(H)(Me) interme-
diate and Ph3SnMe. Rapid Sn-H oxidative addition of
a second molecule of Ph3SnH, followed by reductive
elimination of dihydrogen, yields 6; this complex can
also be generated directly from the Sn-H oxidative
addition of Ph3SnH to 4a, followed by reductive elimi-
nation of methane. Complex 6 could then react with the
remaining Ph3SnH over 4 h to yield a mixture of tin
products, possibly including 7. While the tentative
assignment of 7 as a stannylated derivative of 1[H] is
based on the lack of discernible Pt-P coupling and the
Subsequently, the ability of either 4a or 4b to catalyze
the dehydrogenative dimerization of Ph3SnH to Ph6Sn2
(1 mol % in C6D6) was examined. Unfortunately, under
these conditions the consumption of Ph3SnH was neg-
ligible (119Sn NMR) for reactions conducted in either the
presence or absence of ambient light after 3.5 h. Braun-
stein and co-workers18b have reported that the pal-
ladium-catalyzed dehydrogenative dimerization of Ph3-
SnH can be conducted in a variety of solvents (including
CH2Cl2) without the exclusion of ambient light and that
no modification of the kinetic parameters or TON values
for various catalysts is observed when reactions are
carried out in the presence of radical scavengers and/
or in the dark. On the basis of this report, and in
preparing to survey the catalytic abilities of 4a in CH2-
Cl2, control experiments were carried out in which CD2-
Cl2 solutions of Ph3SnH were monitored (1H and 119Sn
NMR). In the absence of light, no reaction was noted
after 4 days; in contrast, upon exposure to ambient
light for 1 h, greater than 50% conversion to Ph3SnCl
(δ119Sn ) -48)20 was observed, along with a small
amount of Ph6Sn2.23 While no reaction was observed for
Ph3SnH in CD2Cl2 in the presence of 1 mol % 4a in the
dark after 3.5 h, exposure to ambient light under
analogous conditions resulted in the conversion of Ph3-
SnH to a mixture of Ph3SnCl (∼80%) and Ph6Sn2
(∼20%).
Summary and Conclusions
In summary, we have demonstrated that the P,N-
substituted indene 1a[H] can be utilized in the prepara-
tion of (κ2-P,N-1[H])PtX2 complexes, the design of which
is intended to promote the formation of unsaturated
(19) (a) Davies, A. G. In Chemistry of Tin; Harrison, P. G., Ed.;
Chapman and Hall: New York, 1989; Chapter 9. (b) Photolytic cleavage
of Sn-H in Ph3SnH: Schmidt, U.; Kabitzke, K.; Markau, K.; Neumann,
W. P. Chem. Ber. 1965, 98, 3827. (c) Photosensitivity of polymers
containing Sn-H groups: Imori, T.; Lu, V.; Cai, H.; Tilley, T. D. J.
Am. Chem. Soc. 1995, 117, 9931.
(20) (a) Davies, A. G.; Harrison, P. G.; Kennedy, J. D.; Mitchell, T.
N.; Puddephatt, R. J.; McFarlane, W. J. Chem. Soc. (C) 1969, 1136.
(b) McFarlane, W.; Wood, R. J. J. Organomet. Chem. 1972, 40, C17.
(21) Although we are unable to identify the complex that gives rise
to the 119Sn NMR resonance at -228.9 ppm, we have observed this
species (along with Ph6Sn2) as an impurity (up to 20%) in samples of
Ph3SnH obtained from commercial sources.
(22) (a) Almeida, J. F.; Azizian, H.; Earborn, C.; Pidcock, A. J.
Organomet. Chem. 1981, 210, 121. (b) Yoder, C. H.; Margolis, L. A.;
Horne, J. M. J. Organomet. Chem. 2001, 633, 33.
(23) The reduction of alkyl chlorides by R3SnH promoted by exposure
to UV light is well-established: Wardell, J. L. In Chemistry of Tin;
Harrison, P. G., Ed.; Chapman and Hall: New York, 1989; Chapter
10.

1964 Organometallics, Vol. 24, No. 8, 2005
Wile et al.
(for 1H and 13C), 85% H3PO4 in D2O (for 31P), SnMe4 (for
119Sn), or K2PtCl4 in D2O (for 195Pt). In some cases, slightly
reactive intermediates of the type (κ1-P,N-1[H])PtX2.
Although reactions involving 4a and two-electron donors
did not result in the trapping of such intermediates, a
three-coordinate species may be involved in the forma-
tion of the cyclometalated complex, 5, which can be
viewed as arising from an intramolecular C-H activa-
tion process involving (κ1-P,N-1[H])PtMe2 in the pres-
ence of SMe2. However, the role of Lewis bases in
mediating such reactivity remains unclear, as divergent
reaction pathways are observed when alternative donor
molecules are employed (e.g., PPh3, THF, CH3CN,
DMAP). Although 4a also reacts in an intermolecular
fashion with various substrates containing E-H bonds,
complex reactivity is often observed and we have thus
far been unable to isolate any of the products formed
in these reactions. We suspect that cyclometalation
processes analogous to those leading to 5 may contribute
to the complex intermolecular reactivity observed be-
tween 4a and E-H-containing substrates. As such, we
are currently developing variations of 1a[H] that feature
more metalation-resistant donor fragments. The co-
ordination chemistry and reactivity properties of com-
plexes supported by these new ancillary ligands will be
the subject of future reports.
1
fewer than expected independent H or 13C NMR resonances
1
were observed, despite prolonged data acquisition times. H
and 13C NMR chemical shift assignments are based on data
obtained from 1H-1H COSY, 1H-13C HSQC, and 1H-13C
HMBC NMR experiments. Melting points were obtained on
an electrothermal apparatus using samples sealed in capil-
laries under dinitrogen. Elemental analyses were performed
by Canadian Microanalytical Service Ltd., Delta, British
Columbia, Canada. All X-ray data were obtained at 193((2)
K on a Bruker PLATFORM/SMART 1000 CCD diffractometer,
using samples that were mounted in inert oil and transferred
to a cold gas stream on the diffractometer. Crystal structure
diagrams were generated by use of the ORTEP-3 program.25
For complete experimental details and tabulated crystal-
lographic data, see the Supporting Information.
Preparation of 2. Method A. To a Schlenk flask contain-
ing a magnetic stir bar were added 1a[H] (0.017 g, 0.63 mmol)
and a mixture of cis- and trans-[(SMe2)2PtCl2] (0.025 g, 0.63
mmol). The flask was then sealed with a septum, and toluene
(30 mL) was added via cannula to generate a light yellow
solution. Magnetic stirring was initiated, and the solution was
stirred for 16 h. The toluene and other volatile materials were
then removed in vacuo, and the residue was washed with
pentane (2 × 6 mL) and diethyl ether (6 mL). Then residual
solvent was evaporated in vacuo, leaving a light yellow powder,
2 (0.29 g, 0.53 mmol, 84%).
Experimental Section
Method B. To a vial containing a magnetically stirred
suspension of platinum dichloride (0.049 g, 0.18 mmol) in
toluene (2 mL) was added a solution of 1a[H] (0.050 g, 0.18
mmol) in toluene (2 mL). The resulting mixture was stirred
at room temperature for 16 h, after which toluene was
evaporated in vacuo to yield a light brown solid residue. This
solid was dissolved in a minimal amount of dichloromethane
(5 mL) and filtered through Celite to yield a clear, orange
solution. Dichloromethane was removed in vacuo, and the
residue was washed with pentane (2 × 6 mL) to yield a light
yellow powder, 2 (0.054 g, 0.10 mmol, 55%). Pale yellow
crystals suitable for X-ray diffraction were obtained by diffus-
ing diethyl ether into a dichloromethane solution of 2 and
placing the resulting mixture in a freezer at -35 °C. Melting
point: 218-221 °C. Anal. Calcd for C17H26N1P1Cl2Pt1: C 37.72,
General Considerations. All manipulations were con-
ducted in the absence of oxygen and water under an atmo-
sphere of dinitrogen, either by use of standard Schlenk
methods or within an mBraun glovebox apparatus, utilizing
glassware that was oven-dried (130 °C) and evacuated while
hot prior to use. Celite (Aldrich) was oven-dried (130 °C) for 5
days and then evacuated for 24 h prior to use. The nondeu-
terated solvents tetrahydrofuran, dichloromethane, diethyl
ether, toluene, benzene, and pentane were deoxygenated and
dried by sparging with dinitrogen gas, followed by passage
through a double-column solvent purification system provided
by mBraun Inc. Tetrahydrofuran, dichloromethane, and di-
ethyl ether were purified over two alumina-packed columns,
while toluene, benzene, and pentane were purified over one
alumina-packed column and one column packed with copper-
Q5 reactant. Purification of CH3CN was achieved by refluxing
over CaH2 for 4 days under dinitrogen, followed by distillation.
Purification of NEt3 was achieved by stirring over KOH for 7
days, followed by distillation; the distilled NEt3 was then
refluxed over CaH2 for 3 days under dinitrogen, followed by
distillation. CHCl3 was degassed by using three repeated
freeze-pump-thaw cycles, dried over CaH2 for 7 days, and
distilled in vacuo. Technical grade 2-propanol was not purified
prior to use. The solvents used within the glovebox were stored
over activated 3 Å molecular sieves. C6D6 (Aldrich) was
degassed by using three repeated freeze-pump-thaw cycles
and then dried over 3 Å molecular sieves for 24 h prior to use.
Compounds 1a[H],2a (η4-COD)PtClMe,24a cis/trans-[(SMe2)2-
PtCl2],24b and [(µ-SMe2)PtMe2]2,24b were prepared employing
reported methods. With the exception of dihydrogen (99.999%,
Air Liquide-UHP Grade), PtCl2 (Fisher), and Ph3SiH (Strem),
all reagents were obtained from Aldrich and were used as
received (unless otherwise stated); the purification of Ph3SnH
is detailed in the experimental description below. All 1H, 13C,
31P, 119Sn, and 195Pt NMR characterization data were collected
in C6D6 at 300 K on a Bruker AV-500 spectrometer operating
at 500.1, 125.8, 202.5, 186.5, and 107.1 MHz (respectively) with
chemical shifts reported in parts per million downfield of SiMe4
1
H 4.84, N 2.59. Found: C 37.43, H 4.72, N 2.47. H NMR: δ
7.07-7.04 (m, 2H, aryl-CH’s), 7.01-6.99 (m, 2H, aryl-CH’s),
3.06 (s, 6H, N(CH3)2), 2.64 (s, 2H, CH2), 2.46 (m, 2H, P(CHCH3-
CH3)2), 1.32 (dd, 3JPH ) 18.1 Hz, 3JHH ) 7.2 Hz, 6H, P(CHCH3-
3
3
CH3)2), 0.89 (dd, JPH ) 16.9 Hz, JHH ) 7.2 Hz, 6H,
P(CHCH3CH3)2). 13C{1H} NMR: δ 178.5 (s, C2), 143.1 (s, C3a
or C7a), 134.7 (s, C3), 130.0 (s, C7a or C3a), 125.8 (s, aryl-
CH), 125.2 (s, aryl-CH), 124.6 (s, aryl-CH), 121.2 (s, aryl-CH),
3
1
52.7 (s, N(CH3)2), 29.4 (d, JPC ) 10 Hz, CH2), 22.7 (d, JPC
)
36 Hz, P(CHCH3CH3)2), 17.3 (s, P(CHCH3CH3)2), 17.0 (s,
P(CHCH3CH3)2). 31P{1H} NMR: δ 31.2 (s, with Pt satellites
1JPtP ) 3788 Hz).
Preparation of 3. To a Schlenk flask containing a magnetic
stir bar were added 1a[H] (0.13 g, 0.49 mmol) and (η4-COD)-
PtClMe (0.16 g, 0.45 mmol). The flask was then sealed with a
septum, and toluene (7 mL) was added via cannula to generate
a yellow-brown solution. Magnetic stirring was initiated, and
the solution was stirred for 16 h. Toluene and other volatile
materials were then removed in vacuo, and the residue was
washed with pentane (2 × 6 mL) and diethyl ether (2 × 6 mL).
Then residual solvent was evaporated in vacuo to leave a finely
divided, off-white powder, 3 (0.21 g, 0.41 mmol, 91%). Melting
point: 177-180 °C. Anal. Calcd for C18H29N1P1Cl1Pt1: C 41.50,
1
H 5.61, N 2.69. Found: C 41.12, H 5.53, N 2.68. H NMR: δ
7.10-7.06 (m, 3H, aryl-CH’s), 6.99 (m, 1H, aryl-CH), 2.79 (s,
(24) (a) Clark, H. C.; Manzer, L. E. J. Organomet. Chem. 1973, 59,
411. (b) Hill, G. S.; Irwin, M. J.; Levy, C. J.; Rendina, L. M.;
Puddephatt, R. J. Inorg. Synth. 1998, 32, 149.
(25) ORTEP-3 for Windows: Farrugia, L. J. J. Appl. Crystallogr.
1997, 30, 565.

Reactivity of New κ2-[P,N]Pt(II) Complexes
Organometallics, Vol. 24, No. 8, 2005 1965
6H, N(CH3)2), 2.48 (s, 2H, CH2), 2.21 (m, 2H, P(CHCH3CH3)2),
Preparation of 5. In a Schlenk tube containing a magnetic
stir bar, 4a (0.047 g, 0.095 mmol) was dissolved in toluene (3
mL) to form a light brown solution. Dimethyl sulfide (0.018
mL, 0.25 mmol, 2.5 equiv) was added, and the tube was sealed
with a rubber septum and placed in a 70 °C oil bath. Stirring
was initiated, and after 20 min the solution was noted to be
dark brown (nearly black) in color. The solution was stirred
for 20 h, at which time toluene and other volatiles were
removed in vacuo. The product was dissolved in benzene (6
mL) and filtered through Celite to remove small quantities of
insoluble materials. Removal of benzene in vacuo left a dark
brown solid, 5 (0.031 g, 0.057 mmol, 61%). Slow evaporation
of a pentane solution under an atmosphere of dinitrogen
yielded brown crystals suitable for X-ray diffraction. Decom-
position point: 135-137 °C (charring, effervescence). Anal.
Calcd for C20H34N1P1S1Pt1: C 43.95, H 6.27, N 2.56. Found:
3
2
1.42 (d, JPH ) 2.2 Hz, with Pt satellites, JPtH ) 72 Hz, 3H,
Pt-CH3 trans to N), 1.05 (dd, JPH ) 17.1 Hz, 3JHH ) 6.6 Hz, 6H,
3
P(CHCH3CH3)2), 0.85 (dd, 3JPH ) 16.5 Hz, 3JHH ) 7.1 Hz, 6H,
P(CHCH3CH3)2). 13C{1H} NMR: δ 177.1 (d, 2JPC ) 13 Hz, C2),
143.8 (d, JPC ) 6 Hz, C3a or C7a), 138.4 (s, C7a or C3a), 131.9
1
(d, JPC ) 41 Hz, C3), 126.9 (s, aryl-CH), 125.8 (s, aryl-CH),
125.4 (s, aryl-CH), 122.2 (s, aryl-CH), 49.8 (s, N(CH3)2), 30.2
(d, 3JPC ) 10 Hz, CH2), 24.2 (d, 1JPC ) 37 Hz, P(CHCH3CH3)2),
19.1 (s, P(CHCH3CH3)2), 18.6 (s, P(CHCH3CH3)2), -27.2 (d,
2JPC ) 7 Hz, Pt satellites not resolved, Pt-CH3 trans to N).
1
31P{1H} NMR: δ 31.4 (s, with Pt satellites JPtP ) 4487 Hz).
1
195Pt NMR: δ -2558 (d, JPtP ) 4497 Hz).
Preparation of 4a. In a vial containing a magnetic stir
bar, [(µ-SMe2)PtMe2]2 (0.031 g, 0.054 mmol) was suspended
in toluene (3 mL), and stirring was initiated. A light brown
solution of 1a[H] (0.027 g, 0.098 mmol) in toluene (3 mL) was
then added rapidly to the platinum-containing solution. The
resulting mixture was stirred for 3 h, after which time 31P-
{1H} NMR indicated quantitative formation of the allylic
isomer, 4a. The solution was filtered through Celite to remove
unreacted [(µ-SMe2)PtMe2]2, and toluene and other volatiles
were removed in vacuo, yielding a light brown solid, 4a (0.047
g, 0.095 mmol, 97%). Since 4a isomerizes to 4b, elemental
analysis data are provided only for 4b (vide infra). Addition-
ally, 13C NMR chemical shift assignments are made on the
basis of projections of the cross-peaks from 1H-13C HSQC and
1H-13C HMBC NMR experiments. 1H NMR: δ 7.14-7.01 (m,
1
C 44.24, H 6.20, N 2.51. H NMR: δ 7.30-7.23 (m, 2H, aryl-
3
CH’s), 7.21-7.13 (m, 1H, aryl-CH). 6.99 (td, JHH ) 7.0 Hz,
3
4JHH ) 1.5 Hz, 1H, C5 or C6), 4.08 (d, JPH ) 8.5 Hz, with Pt
2
satellites, JPtH ) 93.5 Hz, 2H, N-CH2), 3.01 (s, 2H, C(1)H2),
2.98 (m, 2H, P(CHCH3CH3)2), 2.60 (s, 3H, N-CH3), 1.93 (s with
3
3
Pt satellites, JPtH ) 25.0 Hz, 6H, S(CH3)2), 1.28 (dd, JPH
)
)
)
15.5 Hz, 3JHH ) 7.0 Hz, 6H, P(CHCH3CH3)2), 1.24 (dd, 3JPH
3
3
14.5 Hz, JHH ) 7.0 Hz, 6H, P(CHCH3CH3)2), 1.10 (d, JPH
6.5 Hz, with Pt satellites, JPtH ) 64.3 Hz, 3H, Pt-CH3). 13C-
2
{1H} NMR: δ 169.2 (d, JPC ) 13 Hz, C2), 149.3 (s, C3a or
2
C7a), 135.5 (d, J ) 7 Hz, C7a or C3a), 126.5 (s, aryl-CH), 122.9
(s, aryl-CH), 119.6 (s, aryl-CH), 118.3 (s, aryl-CH), 88.8 (d, 1JPC
) 51 Hz, C3), 41.7 (s with Pt satellites, 3JPtC ) 31 Hz, N-CH3),
2
4H, aryl-CH’s), 5.70 (s, 1H, vinyl-H), 3.82 (d, JPH ) 10.5 Hz,
3
3
2
1H, allylic-H), 2.72 (s with Pt satellites, JPtH ) 14.5 Hz, 3H,
39.8 (d, JPC ) 6 Hz, C1), 38.0 (d, JPC ) 8 Hz, N-CH2), 25.3
3
1
NCH3aCH3b), 2.68 (s with Pt satellites, JPtH ) 16.3 Hz, 3H,
(d, JPC ) 27 Hz, P(CHCH3CH3)2), 20.6 (s, P(CHCH3CH3)2),
NCH3aCH3b), 2.14 (m, 1H, P(CHCH3aCH3b)), 2.08 (s with Pt
20.1 (d, 2JPC ) 6 Hz, P(CHCH3CH3)2), 19.1 (s, S(CH3)2), 9.6 (d,
2JPC ) 99 Hz, with Pt satellites, 1JPtC ) 667 Hz, Pt-CH3). 31P-
satellites, 2JPtH ) 20.0 Hz, 3H, Pt-CH3 trans to N), 1.85 (m,
3
3
1
1H, P(CHCH3cCH3d)), 1.39 (dd, JPH ) 16.8 Hz, JHH ) 7.2
{1H} NMR: δ 16.8 (s, with Pt satellites JPtP ) 2006 Hz).
3
3
Hz, 3H, P(CHCH3cCH3d)), 1.04 (dd, JPH ) 18.0 Hz, JHH
7.5 Hz, 3H, P(CHCH3cCH3d)), 0.99 (s, Pt satellites not resolved,
3H, Pt-CH3 trans to P), 0.83 (dd, JPH ) 14.7 Hz, JHH ) 7.3
Hz, 3H, P(CHCH3aCH3b)), 0.62 (dd, JPH ) 16.5 Hz, JHH
)
Reactions Involving Ph3SnH. All experiments were
conducted in duplicate using Ph3SnH that was purified by
extraction into diethyl ether, followed by filtration through
Celite to remove insoluble impurities and removal of the
solvent to yield purified Ph3SnH (based on 1H and 119Sn NMR
data). Unless otherwise stated, each reaction was carried out
without exclusion of ambient light by adding a solution of an
appropriate amount of either 4a or 4b in 0.75 mL of either
C6D6 or CD2Cl2 to a glass vial containing Ph3SnH (30 mg, 0.086
mmol). A homogeneous mixture formed instantly, and this
mixture was then transferred immediately to an NMR tube,
which was subsequently capped and sealed with PTFE tape.
The resulting light brown solutions were observed to darken
to orange-brown over 1 min and then to dark orange after 10
min. Clear, homogeneous mixtures were maintained through-
out, and for reactions employing a Ph3Sn:4a ratio of 10:1, gas
evolution was also observed. The progress of each reaction was
monitored periodically by use of NMR techniques, with the
relative product distribution estimated from the ratio of the
peak heights in the spectrum (for 31P and 119Sn NMR). Details
of specific experiments are provided in the text.
3
3
3
3
)
6.7 Hz, 3H, P(CHCH3aCH3b)). 13C{1H} NMR: δ 170.0 (C2),
144.2 (C3a), 137.0 (C7a), 127.0 (aryl-CH), 124.4 (aryl-CH’s),
121.3 (aryl-CH), 113.6 (vinyl-CH), 50.8 (NCH3aCH3b), 46.7
(NCH3aCH3b), 45.8 (allylic-CH), 23.3 (P(CHCH3aCH3b)), 21.4
(P(CHCH3cCH3d)), 20.1 (Pt-CH3 trans to N), 19.3 (P(CHCH3-
cCH3d)), 18.5 (P(CHCH3cCH3d)), 18.1 (P(CHCH3aCH3b)), 17.4
(P(CHCH3aCH3b)), -7.1 (Pt-CH3 trans to P). 31P{1H} NMR:
1
δ 27.6 (s, with Pt satellites JPtP ) 2063 Hz).
Preparation of 4b. To a magnetically stirred solution of
i
4a (0.103 g, 0.206 mmol) in THF (10 mL) was added PrOH
(2.5 mL). After 1 h, clean conversion to 4b (31P NMR) was
achieved. The solvents and other volatiles were removed in
vacuo to yield 4b (0.102 g, 0.204 mmol, 99%) as an analytically
pure light brown solid. Decomposition point: 109-114 °C
(charring, effervescence). Anal. Calcd for C19H32N1P1Pt1: C
45.59, H 6.44, N 2.80. Found: C 45.22, H 6.38, N 2.67. 1H NMR
(C6D6): δ 7.28-7.10 (m, 4H, aryl-CH’s), 2.62 (s, 6H, N(CH3)2),
3
2.60 (s, 2H, CH2), 2.44 (m, 2H, P(CHCH3CH3)2), 1.49 (d, JPH
Acknowledgment is made to the Natural Sciences
and Engineering Research Council (NSERC) of Canada,
the Canada Foundation for Innovation, the Nova Scotia
Research and Innovation Trust Fund, and Dalhousie
University for their generous support of this work. We
also thank Drs. Bob Berno and Michael Lumsden
(Atlantic Region Magnetic Resonance Center, Dalhou-
sie) for assistance in the acquisition of NMR data.
) 6.5 Hz, with Pt satellites, 2JPtH ) 90.5 Hz, 3H, Pt-CH3 trans
to N), 1.29 (dd, 3JPH ) 16.0 Hz, 3JHH ) 7.0 Hz, 6H, P(CHCH3-
3
2
CH3)2), 1.09 (d, JPH ) 7.0 Hz, with Pt satellites, JPtH ) 63.5
Hz, 3H, Pt-CH3 trans to P), 1.00 (dd, 3JPH ) 14.8 Hz, 3JHH
)
6.9 Hz, 6H, P(CHCH3CH3)2). 13C{1H} NMR: δ 176.7 (d, JPC
) 20 Hz, C2), 144.0 (d, 1JPC ) 4 Hz, C3), 139.9 (s, C7a), 136.1
(s, C3a), 126.8 (s, C6 or C7), 125.5 (s, C4), 125.2 (s, C5), 122.3
(s, C7 or C6), 49.8 (s, N(CH3)2), 29.5 (d, 3JPC ) 9 Hz, C1), 24.7
2
1
(d, JPC ) 23 Hz, P(CHCH3CH3)2), 19.7 (s, P(CHCH3CH3)2),
Supporting Information Available: Tabulated single-
crystal X-ray diffraction data for 2 and 5 are available free of
charge via the Internet at http://pubs.acs.org.
19.3 (d, 2JPC ) 7 Hz, P(CHCH3CH3)2), 17.4 (d, 2JPC ) 111 Hz,
Pt satellites not resolved, Pt-CH3 trans to P), -27.2 (d, 2JPC
) 4 Hz, Pt satellites not resolved, Pt-CH3 trans to N). 31P-
{1H} NMR: δ 39.2 (s, with Pt satellites JPtP ) 2039 Hz).
OM049034W
1