Stoichiometric and catalytic behavior of cationic silyl and silylene complexes

Article abstract of DOI:10.1021/om0203173

Reactions of Ir(III) silyl and silylene complexes with a variety of unsaturated substrates were investigated. The reactivity of these complexes toward small molecules was also examined, and this led to the discovery of a nitrile carbon-carbon bond cleavage under mild conditions. Both silyl and silylene complexes of Ir(III) are precatalysts for catalytic hydrosilylation of ketones, and the mechanism of this reaction is discussed. In the course of studying the catalytic reaction mechanism, analogous new ruthenium silylene complexes of the form [Cp*(PMe₃)₂Ru(SiR₂)] [B(C₆F₅)₄] (Cp* = η⁵-C₅Me₅, R = ⁱPr, SPh) were prepared. A comparison of [Cp*(PMe₃)Ir(SiPh₂)(H)] [B(C₆F₅)₄] and the known Lewis acid hydrosilylation catalyst B(C₆F₅)₃ is also made.

Full text of DOI:10.1021/om0203173

4648
Organometallics 2002, 21, 4648-4661
Stoich iom etr ic a n d Ca ta lytic Beh a vior of Ca tion ic Silyl
a n d Silylen e Com p lexes
Steven R. Klei, T. Don Tilley,* and Robert G. Bergman*
Department of Chemistry, University of California, Berkeley, California 94720, and Chemical
Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
Received April 22, 2002
Reactions of Ir(III) silyl and silylene complexes with a variety of unsaturated substrates
were investigated. The reactivity of these complexes toward small molecules was also
examined, and this led to the discovery of a nitrile carbon-carbon bond cleavage under mild
conditions. Both silyl and silylene complexes of Ir(III) are precatalysts for catalytic
hydrosilylation of ketones, and the mechanism of this reaction is discussed. In the course of
studying the catalytic reaction mechanism, analogous new ruthenium silylene complexes of
i
the form [Cp*(PMe3)2Ru(SiR2)][B(C6F5)4] (Cp* ) η5-C5Me5, R ) Pr, SPh) were prepared. A
comparison of [Cp*(PMe3)Ir(SiPh2)(H)][B(C6F5)4] and the known Lewis acid hydrosilylation
catalyst B(C6F5)3 is also made.
In tr od u ction
discovery of mild C-H activation behavior by the Ir(III)
complex Cp*(PMe3)Ir(Me)OTf (OTf ) OSO2CF3, 1).11
The novel stoichiometric reactivity associated with the
related compounds Cp*(PMe3)Ir(Me)(CH2Cl2)][X] (2, X
) B(3,5-(CF3)2C6H3)4 ) BArf, MeB(C6F5)3) and [Tp*-
(PMe3)Ir(Me)(N2)][BArf] (3) has been reported re-
cently.12,13 When comparing the rates of C-H activation
by 1 and 2, the observed increase in reaction rate that
can be achieved through anion metathesis is clearly
evident.
A major focus of organometallic chemistry has been
the enhancement of both the stoichiometric and catalytic
reactivity of metal complexes through the generation
of open coordination sites.1,2 Two pathways available in
pursuit of such a goal are neutral (eq 1) and anionic (eq
2) ligand dissociation. Although there is some evidence
Attempts to generate and study silyl analogues of 1
led to the observation of facile 1,2-group migration from
silicon to iridium to give Cp*(PMe3)Ir(SiR2OTf)(R) as
the products (eq 3). These products can be viewed as
to suggest that neutral ligand dissociation can be
enhanced by the presence of added Lewis acids,3,4
increasing anionic ligand dissociation of metal com-
plexes through anion metathesis with salts of weakly
coordinating anions has generally proven to be more
straightforward.5-7 Both early and late transition metal
polymerization chemistry has benefited from this ap-
proach, and evidence exists that stoichiometric reactiv-
ity can be similarly affected.8-10
metal silylene complexes that are stabilized by the
coordination of triflate to silicon. Silylene complexes are
postulated intermediates in a number of transition
metal-catalyzed reactions involving organosilanes, in-
cluding the Direct Process.14 Iridium silylene complexes
have been invoked as intermediates in a number of
reactions, including the reaction of (TFB)Ir(OCOCH3)-
(PR3) to give (TFB)Ir(H)2(PR3)SiPh2(OCOCH3) (TFB )
tetrafluorobenzobarrelene; R ) Ph, Cy, iPr), the reaction
We have been interested in the reaction chemistry
associated with cationic Ir(III) alkyl complexes since the
(1) Crabtree, R. H. The Organometallic Chemistry of the Transition
Metals, 2nd ed.; Wiley-Interscience: New York, 1994.
(2) Collman, J . P.; Hegedus, L. S.; Norton, J . R.; Finke, R. G.
Principles and Applications of Organotransition Metal Chemistry;
University Science: Sausalito, CA, 1987.
(3) Dias, E. L.; Nguyen, S. T.; Grubbs, R. H. J . Am. Chem. Soc. 1997,
119, 3887.
of (η2-MesHSi(CH2)2PPh2)Ir(PMe3)2(Me)(H) with MeOH
to afford (η2-Mes(MeO)Si(CH2)2PPh2)Ir(PMe3)2(H)2, and
(4) Dioumaev, V. K.; Plossl, K.; Carroll, P. J .; Berry, D. H. J . Am.
Chem. Soc. 1999, 121, 8391.
rearrangements involving (Me3P)3IrSi(SiMe3)3.15-17
(5) Reed, C. A. Acc. Chem. Res. 1998, 31, 133 and references therein.
(6) Chen, E. Y. X.; Marks, T. J . Chem. Rev. 2000, 100, 1391.
(7) Thayer, A. M. Chem. Eng. News 1995, 73, 15.
(8) Reinartz, S.; White, P. S.; Brookhart, M.; Templeton, J . L.
Organometallics 2001, 20, 1709.
(9) Holtcamp, M. W.; Labinger, J . A.; Bercaw, J . E. J . Am. Chem.
Soc. 1997, 119, 848.
(11) Burger, P.; Bergman, R. G. J . Am. Chem. Soc. 1993, 115, 10462.
(12) Klei, S. R.; Golden, J . T.; Burger, P.; Bergman, R. G. J . Mol.
Catal. A 2002, accepted for publication.
(13) Tellers, D. M.; Bergman, R. G. J . Am. Chem. Soc. 2000, 122,
954.
(14) Brook, M. A. Silicon in Organic, Organometallic, and Polymer
Chemistry; Wiley-Interscience: New York, 2000.
(10) Arndtsen, B. A.; Bergman, R. G. Science 1995, 270, 1970.
10.1021/om0203173 CCC: $22.00 © 2002 American Chemical Society
Publication on Web 10/05/2002

Stoichiometric Behavior of Cationic Silyl and Silylene Complexes
Organometallics, Vol. 21, No. 22, 2002 4649
Establishing the reactivity patterns of metal silylenes
has been hampered by the small number of methods
that provide access to them. The first base-free metal
silylene complexes to be isolated were [Cp*(PMe3)2Ru-
(Si(SR)2)][BPh4] (R ) p-tol, Et), which were reported in
1990.18 The list of isolable base-free metal silylene
complexes now includes complexes of platinum,19 iri-
dium,20,21 osmium,22 tungsten,23,24 and molybdenum.25
Reactions of silylene complexes with unsaturated
substrates to afford isolable products are rare. Cycload-
dition of base-free ruthenium silylene complexes with
isocyanates is known,26 and the complex [Cp*(PMe3)2-
RuSiPh2(NCMe)][BPh4] reacts with enolizable ketones
to generate the corresponding silyl enol ether and [Cp*-
(PMe3)2Ru(NCMe)][BPh4].27 Other known reactions of
silylene complexes include coordination to Lewis bases28
and a halogen atom abstraction by an osmium silylene
complex, in which the silylene ligand facilitates a redox
reaction at the metal center.22
with evidence that these complexes are likely interme-
diates in rearrangement reactions at silicon. Here we
present an investigation of the stoichiometric and
catalytic reactivity of these new metal silylene com-
plexes.
Resu lts
Stoich iom etr ic Reactivity of[Cp*(P Me3)Ir (SiMes2)-
(H)][OTf] (4). Treatment of [Cp*(PMe3)Ir(SiMes2)(H)]-
[OTf] (4) with 1 equiv of p-tolualdehyde results in the
clean formation of {Cp*(PMe3)Ir(H)[κ2-Si(2-CH2-4,6-
(CH3)2C6H2)(Mes)(OCH2(p-tolyl))]}[OTf} (6), which was
1
isolated in 85% yield (eq 4). The H NMR spectrum of 6
There are a number of reasons to study the insertion
behavior of silyliridium(III) complexes, especially if
catalytic processes involving them are to be developed.
The traditional Chalk-Harrod mechanism for hydrosi-
lylation cannot account for the formation of dehydro-
genative silylated products,14 and Brookhart and co-
workers have provided evidence for an alternative
pathway that proceeds by insertion into a metal-silicon
bond.29,30 The formation of dehydrogenated products in
hydrosilylation reactions is explained by insertion of the
unsaturated substrate into a metal-silicon bond, fol-
lowed by â-hydrogen elimination from the newly formed
metal alkyl species. Direct observations of metal-
containing insertion products are limited in number,
with late-metal examples including platinum31,32 and
ruthenium.33
displays the expected resonances for the Cp* (δ 1.67, d,
J P-H ) 2 Hz) and PMe3 ligands (δ 1.45, d, J P-H ) 11
Hz), as well as resonances for the diastereotopic protons
on the metalated carbon (δ 3.49, d, J H-H ) 14 Hz; δ 2.90,
vt, J H-H ) 14 Hz) and diastereotopic benzylic ether
protons (δ 4.83, d, J P-H ) 12 Hz; δ 4.43, d, J P-H ) 12
Hz). Additional spectroscopic evidence for the proposed
structure includes the phosphorus-coupled 13C NMR
We have previously discussed the synthesis of the
silylene complexes [Cp*(PMe3)Ir(SiMes2)(H)][OTf] (4)
resonance for the metalated carbon (δ 13.0, d, J P-C
)
10 Hz), and an infrared stretch for the iridium-hydride
and [Cp*(PMe3)Ir(SiPh2)(H)][B(C6F5)4] (5),20,34 along
bond (νIr-H ) 2163 cm-1).
Reactions of dimesitylsilylene complex 4 with unsat-
urated hydrocarbon substrates were subsequently in-
vestigated. However, no reaction was observed when 4
was treated with 1 equiv of ethylene after heating to
45 °C for 4 d. Further heating led only to decomposition,
and reaction of 4 with 2-butyne showed no conversion
after 30 min at 25 °C. Presumably, complex 4 is too
crowded to undergo migratory insertion reactions with
these substrates.
(15) Esteruelas, M. A.; Nurnberg, O.; Olivan, M.; Oro, L. A.; Werner,
H. Organometallics 1993, 12, 3264.
(16) Okazaki, M.; Tobita, H.; Kawano, Y.; Inomata, S.; Ogino, H. J .
Organomet. Chem. 1998, 553, 1.
(17) Mitchell, G. P.; Tilley, T. D.; Yap, G. P. A.; Rheingold, A. L.
Organometallics 1995, 14, 5472.
(18) Straus, D. A.; Grumbine, S. D.; Tilley, T. D. J . Am. Chem. Soc.
1990, 112, 7801.
(19) Feldman, J . D.; Mitchell, G. P.; Nolte, J . O.; Tilley, T. D. J .
Am. Chem. Soc. 1998, 120, 11184.
(20) Klei, S. R.; Tilley, T. D.; Bergman, R. G. J . Am. Chem. Soc.
2000, 122, 1816.
(21) Peters, J . C.; Feldman, J . D.; Tilley, T. D. J . Am. Chem. Soc.
1999, 121, 9871.
(22) Wanandi, P. W.; Glaser, P. B.; Tilley, T. D. J . Am. Chem. Soc.
2000, 122, 972.
(23) Mork, B. V.; Tilley, T. D. J . Am. Chem. Soc. 2001, 123, 9702.
(24) Ueno, K.; Asami, S.; Watanabe, N.; Ogino, H. Organometallics
2002, 21, 1326.
(25) Mork, B. V.; Tilley, T. D. Manuscript in preparation.
(26) Mitchell, G. P.; Tilley, T. D. J . Am. Chem. Soc. 1997, 119, 11236.
(27) Zhang, C.; Grumbine, S. D.; Tilley, T. D. Polyhedron 1991, 10,
1173.
(28) Grumbine, S. K.; Mitchell, G. P.; Straus, D. A.; Tilley, T. D.
Organometallics 1998, 17, 5607.
(29) Brookhart, M.; Grant, B. E. J . Am. Chem. Soc. 1993, 115, 2151.
(30) LaPointe, A. M.; Rix, F. C.; Brookhart, M. J . Am. Chem. Soc.
1997, 119, 906.
(31) Yamashita, H.; Tanaka, M.; Goto, M. Organometallics 1993,
12, 988.
(32) Ozawa, F.; Kamite, J . Organometallics 1998, 17, 5630.
(33) Maddock, S. M.; Rickard, C. E. F.; Roper, W. R.; Wright, L. J .
Organometallics 1996, 15, 1793.
The reactivity of dimesitylsilylene complex 4 was also
examined toward substrates not expected to react via
insertion. Upon addition of MeOH to a CD2Cl2 solution
of 4, the bright yellow color immediately bleaches and
[Cp*(PMe3)Ir(H)3][OTf] is observed by 1H and 31P NMR
spectroscopy as the only organometallic product.35 The
major silicon-containing product of this reaction is
1
presumably Mes2Si(OMe)2, although H NMR and GC/
MS analysis after extraction into pentane indicates a
mixture of organic products which could not be purified
by crystallization. Addition of CCl4 to 4 does not result
in the formation of [Cp*(PMe3)Ir(SiMes2)(Cl)][OTf] after
heating to 45 °C for 24 h, presumably due to steric
hindrance. In fact, complex 4 displayed a surprising lack
of reactivity with added Lewis bases such as pyridine
(34) Klei, S. R.; Tilley, T. D.; Bergman R. G. Submitted for publica-
tion.
(35) Oldham, W. J .; Hinkle, A. S.; Heinekey, D. M. J . Am. Chem.
Soc. 1997, 119, 11028.

4650 Organometallics, Vol. 21, No. 22, 2002
Klei et al.
and CH3CN. The bulky environment around silicon also
accounts for the fact that 4 is the first cationic transition
metal silylene complex that does not coordinate triflate.
Treatment of 4 with other Lewis bases, such as CNtBu
and CO, led to the formation of multiple products.
An effort was made to prepare the neutral iridium
silylene complex Cp*(PMe3)Ir(SiMes2) by deprotonation
of 4. Reaction with either KN(SiMe3)2 or lithium 2,2,6,6-
tetramethylpiperidide led to production of a deep red
solution that was found to contain multiple products by
1H and 31P NMR spectroscopy. To assess the possibility
that the putative neutral silylene complex might be
inherently unstable, attempts were made to trap it.
However, inclusion of an excess (10 equiv) of dipheny-
lacetylene, benzophenone, p-tolyl disulfide, or diphe-
nylsilane had little effect on the decomposition induced
by added lithium 2,2,6,6-tetramethylpiperidide.
Stoich iom etr ic Reactivity of [Cp*(P Me3)Ir (SiP h 2)-
(H)][B(C6F 5)4] (5). Although studies of dimesitylsi-
lylene complex 4 revealed a number of new metal silyl
tranformations, its limited reactivity with Lewis bases
suggested that a more reactive complex could be found
if the size of the substituents at silicon was reduced.
Because of the propensity of tertiary iridium silyl
complexes to cyclometalate in this system,20,36 the
synthesis of a new iridium silylene complex was ap-
proached by using a secondary silane. The less hindered
silylene complex [Cp*(PMe3)Ir(SiPh2)(H)][B(C6F5)4] (5)
is readily available by treatment of Cp*(PMe3)Ir(Me)OTf
with H2SiPh2, followed by anion metathesis with (Et2O)2-
LiB(C6F5)4.12
hyde led to a dark brown mixture containing numerous
unidentified compounds. Similarly, treatment of 5 with
1 equiv of either 2-butyne or 1,2-propadiene led to
formation of at least three products. Reaction of 5 with
di-p-tolylcarbodiimide also did not result in clean reac-
tion behavior.
Deprotonation was considered as a possible synthetic
route to Cp*(PMe3)Ir(SiPh2) as either a stable entity or
a species that could be trapped, as was described for
silylene complex 4. However, reaction of 5 with the
hindered base KN(SiMe3)2 led to formation of Cp*-
(PMe3)Ir[SiPh2N(SiMe3)2](H) (8) in 41% isolated yield.
This complex is readily soluble in nonpolar solvents such
1
as pentane and Et2O, and exhibits the expected H NMR
spectroscopic characteristics. Unfortunately, addition of
lithium 2,2,6,6-tetramethylpiperidide to 5 led only to
decomposition, and use of an excess (10 equiv) of
diphenylacetylene, benzophenone, p-tolyl disulfide, or
diphenylsilane had little effect on the outcome of the
reaction.
Rea ctivity of [Cp *(P Me3)Ir (η2-SiP h 2C6H4)(H)]-
[B(C6F 5)4] (9). As previously described, cyclometalated
complex 9 is obtained by treating Cp*(PMe3)Ir(SiPh2-
OTf)(Ph) with (Et2O)2LiB(C6F5)4.20 Studying the reactiv-
ity of this species could provide insight into the behavior
of the 16-electron iridium silyl complex “[Cp*(PMe3)Ir-
(SiPh3)][B(C6F5)4]” if C-H reductive elimination to form
the triphenylsilyl ligand is facile for 9.
The insertion behavior of cyclometalated silyliridium
complex 9 toward a carbonyl-containing substrate was
examined. Reaction of 9 with p-tolualdehyde is complete
Silylene complex 5 reacts with 4-ethynyltoluene at 25
°C within minutes to give spectroscopically pure {Cp*-
(PMe3)Ir[SiPh2(η2-CHCH(p-tolyl))]}[B(C6F5)4] (7) in 81%
isolated yield (eq 5). As cationic 16-electron iridium silyl
within 10 min at 25 °C, and {Cp*(PMe3)Ir[κ2-(C6H4-2-
SiPh2)(OCH2(p-tolyl))]}[B(C6F5)4] (10) is obtained in 48%
1
recrystallized yield (eq 6). A H NMR spectrum of 10
complexes are electron deficient, it is not too surprising
that the carbon-carbon double bond in the styrenyl
ligand coordinates to the metal center. The 13C NMR
spectrum for this complex contains upfield resonances
at δ 66.3 and 38.6, which are consistent with a coordi-
nated olefin. Structural evidence for the olefinic group
indicates resonances for the Cp* (δ 1.41, d, J P-H ) 2
Hz) and PMe3 (δ 1.23, d, J P-H ) 10 Hz) ligands, as well
as diagnostic resonances for the diastereotopic protons
of the benzylic methylene group (δ 5.55, d, J H-H ) 12
Hz; δ 4.80, d, J H-H ) 12 Hz). This complex was also
characterized by X-ray crystallography, providing de-
finitive evidence for a bonding interaction between
oxygen and iridium (2.251(3) Å). An ORTEP diagram
of the cationic portion of 10 is seen in Figure 1, and
representative bond lengths and angles are found in
Table 1.
Reaction of Cp*(PMe3)Ir(SiPh2OTf)(Ph) with NaBArf
(BArf ) (3, 5-(CF3)2C6H3)4B), followed by addition of
acetonitrile, provides [Cp*(PMe3)Ir(NCCH3)(SiPh3)]-
[BArf] (11a ) in high yield.20 Similarly, reaction of 9 with
acetonitrile was found to be an effective method for
1
can also be found in the H NMR spectrum (δ 5.29, vt,
J H-H ) 14 Hz; δ 3.52, d, J H-H ) 15 Hz).
The base-free silylene complex 5 is expected to be
more reactive than dimesitylsilylene complex 4 because
the substituents on silicon are smaller. This was found
to be the case experimentally, although competing side
reactions often led to production of multiple products.
For example, reaction of 5 with 1 equiv of p-tolualde-
(36) Klei, S. R.; Tilley, T. D.; Bergman, R. G. Organometallics 2001,
20, 3220.

Stoichiometric Behavior of Cationic Silyl and Silylene Complexes
Organometallics, Vol. 21, No. 22, 2002 4651
Ta ble 2. Selected Bon d d ista n ces (Å) a n d An gles
(d eg) for 11a
bond
distance
bond
angle
Ir-P
2.312(3)
2.411(2)
2.042(9)
1.9033(4)
1.106(11)
P-Ir-Si
91.15(10)
89.5(3)
90.5(2)
129.41(7)
124.60(8)
Ie-Si
P-Ir-N
Ir-N
Ir-C100
N-C11
Si-Ir-N
P-Ir-C100
Si-Ir-C100
Heating a CD2Cl2 solution of acetonitrile complex 11b,
which is formed in situ by reaction of 9 with acetonitrile,
to 75 °C for 24 h leads to nitrile cleavage and production
of isocyanide complex [Cp*(PMe3)Ir(CH3)(CNSiPh3)]-
[B(C6F5)4] (12a ) (eq 7). This complex exhibits the
F igu r e 1. ORTEP diagram of the cationic portion of {Cp*-
(PMe3)Ir[κ2-(C6H4-2-SiPh2)(OCH2(p-tolyl))]}[B(C6F5)4] (10).
Thermal ellipsoids are shown at the 50% probability level.
Hydrogen atoms have been omitted for clarity.
Ta ble 1. Selected Bon d d ista n ces (Å) a n d An gles
(d eg) for 10
1
expected H NMR spectroscopic resonances, including
a resonance typical of an iridium-bound methyl group
(δ 0.44, d, J P-C ) 6 Hz). Concurrent work involving an
X-ray crystallographic study of the related rhodium
species [Cp*(PMe3)Rh(CH3)(CNSiPh3)][B(3,5-(CF3)2-
C6H3)4] suggests the formulation of 12a as an isonitrile
complex, rather than a nitrile complex.37 A similar
nitrile cleavage reaction was observed when cyclometa-
lated complex 9 was treated with benzonitrile. This
reaction occurs more rapidly than does the analogous
reaction with acetonitrile, as [Cp*(PMe3)Ir(Ph)(CNSiPh3)]-
[B(C6F5)4] (13a ) was produced cleanly after heating to
45 °C for 4 h.
bond
distance
bond
angle
Ir-P
2.284(2)
2.251(3)
2.083(5)
1.7438(2)
1.701(4)
P-Ir-C15
P-Ir-O
O-Ir-C15
P-Ir-C100
Si-O-C32
86.1(1)
91.85(9)
82.4(2)
127.76(4)
128.4(3)
Ir-O
Ir-C15
Ir-C100
Si-O
-
It might be suspected that the B(C6F5)4 anion is
essential to these C-C activation reactions, given the
increased reactivity observed for similar Ir(III) com-
plexes upon replacing the triflate anion with a more
weakly coordinating anion. However, treatment of Cp*-
(PMe3)Ir(SiPh2OTf)(Ph) with 1.2 equiv of acetonitrile in
CH2Cl2 at 75 °C for 24 h leads to formation of the C-C
activated product [Cp*(PMe3)Ir(CH3)(CNSiPh3)][OTf]
(12b). Additionally, reaction of benzonitrile at 45 °C for
4 h with Cp*(PMe3)Ir(SiPh2OTf)(Ph) also leads to C-C
activation and production of [Cp*(PMe3)Ir(Ph)(CNSiPh3)]-
[OTf] (13b). Because the anions of these C-C activated
products are outer-sphere, it is not surprising that the
borate and triflate complexes exhibit nearly identical
NMR spectroscopic shifts. Therefore, the nitrile cleavage
products were fully characterized as their more crystal-
line triflate salts. Interestingly, nitrile cleavage is not
observed upon heating a CD2Cl2 solution of Cp*-
(PMe3)Ir(SiPh2OTf)(H) with acetonitrile to 75 °C for 3
h; the adduct [Cp*(PMe3)Ir(SiPh2H)(NCCH3)][OTf] was
also not spectroscopically observable in this case. This
F igu r e 2. ORTEP diagram of the cationic portion of [Cp*-
(PMe3)Ir(NCCH3)(SiPh3)][BArf] (11a ). Thermal ellipsoids
are shown at the 50% probability level. Hydrogen atoms
have been omitted for clarity.
generating [Cp*(PMe3)Ir(NCCH3)(SiPh3)][B(C6F5)4] (11b).
Complex 11a was characterized crystallographically
through an X-ray diffraction study, and an ORTEP
diagram of the cationic portion of it is shown in Figure
2. Representative bond angles and lengths are found in
Table 2.
(37) This experiment was inspired by a similar observation made
by F.L. Taw in the corresponding cationic rhodium system. See: Taw,
F. L.; Brookhart, M.; Bergman, R. G. J . Am. Chem. Soc. 2002, 124,
4192.

4652 Organometallics, Vol. 21, No. 22, 2002
Klei et al.
Sch em e 1
Sch em e 2
lack of reactivity is attributed to the apparently unfa-
vorable process of iridium-hydride migration back to
silicon.
by treating the cationic iridium monohydride complex
[Cp*(PMe3)Ir(H)(CD2Cl2)][CH3B(C6F5)3] with Ph3SiH.38
Because of the readily reversible nature of the 1,2-
phenyl migration in the complex Cp*(PMe3)Ir(SiPh2-
OTf)(Ph), it has the potential to behave as “Cp*(PMe3)-
Ir(SiPh3)(OTf)” when engaged in reactions with added
ligands. When Cp*(PMe3)Ir(SiPh2OTf)(Ph) is treated
with 1 equiv of p-tolualdehyde in CD2Cl2 the solution
darkens over the course of 2 min, and a complicated
mixture of products is detected by 1H and 31P NMR
spectroscopy. This reaction outcome stands in contrast
to that observed with the silyliridium complex contain-
ing a more weakly coordinating anion, which, as de-
scribed, reacts with the aldehyde to afford cyclometa-
lated species 10.
Given that silyliridium complexes were active in
nitrile cleavage reactions, it seemed reasonable to expect
that the corresponding methyliridium complexes would
undergo similar transformations. In that case, the
known acetonitrile complex [Cp*(PMe3)Ir(CH3)(NCCH3)]-
[OTf]12 would be expected to undergo a degenerate
reaction upon thermolysis that would exchange the
iridium-bound methyl group with the methyl group of
the bound acetonitrile. To investigate this possibility,
the complex [Cp*(PMe3)Ir(CH3)(NCCD3)][OTf] was pre-
pared from reaction of Cp*(PMe3)Ir(CH3)(OTf) with CD3-
CN in CD2Cl2. However, there was no observable
isotopic scrambling upon heating [Cp*(PMe3)Ir(CH3)-
(NCCD3)][OTf] in CD2Cl2 at 105 °C for 15 h, and
thermolysis at 135 °C for days led to decomposition with
no evidence of nitrile cleavage. The ability of the
silyliridium complexes to undergo C-C activation might
therefore be due to the energetic accessibility of a
silicon-stabilized Ir(V) intermediate on the pathway.
Rea ctivity of [Cp *(P Me3)Ir (η2-CH2SiMe2)(H)][B-
(C6F 5)4] (16). As mentioned previously, reaction of Cp*-
(PMe3)Ir(SiMe2OTf)(Me) with 1 equiv of (Et2O)2LiB-
(C6F5)4 in CH2Cl2 at 25 °C produced an equilibrium
mixture of silene complex [Cp*(PMe3)Ir(η2-CH2SiMe2)-
(H)][B(C6F5)4] (16) and base-stabilized silylene complex
[Cp(PMe3)Ir(SiMe2(Et2O))(Me)][B(C6F5)4] (17).36 Treat-
ment of a mixture of 16 and 17 with pyridine produced
[Cp*(PMe3)Ir(Me)(SiMe2(py))][B(C6F5)4] (18) in 75% iso-
lated yield as a bright yellow crystalline solid (Scheme
2). The related complex, [Cp*(PMe3)Ir(Me)(SiMe2(py))]-
[OTf] (19), was prepared in 98% isolated yield by
treating the migrated triflate species Cp*(PMe3)Ir(Me)-
(SiMe2OTf) (2) with 1 equiv of pyridine. In contrast to
the reaction with pyridine, treatment of 16 and 17 with
carbon monoxide provided the nonmigrated silyl carbo-
nyl complex [Cp*PMe3Ir(SiMe3)(CO)][B(C6F5)4] (20) in
69% recrystallized yield (Scheme 1). This change in
Cyclometalated complex [Cp*(PMe3)Ir(η2-SiPh2C6H4)-
(H)][B(C6F5)4] (9) is also reactive toward carbon mon-
oxide and dihydrogen. The reaction with CO affords the
Ir(III) carbonyl complex [Cp*(PMe3)Ir(CO)(SiPh3)][B-
(C6F5)4] (14) in 83% yield (Scheme 1). The iridium-
carbonyl functionality is evident from 13C NMR (δ 169.3,
d, J P-C ) 11 Hz) and IR (νCO ) 2029 cm-1) spectroscopy.
Addition of 1 atm of dihydrogen to complex 9 leads to
formation of the Ir(V) complex [Cp*(PMe3)Ir(H)2(SiPh3)]-
[B(C6F5)4] (15) in 87% yield after recrystallization
(Scheme 1). A similar complex may also be generated
(38) Golden, J . T. Ph.D. Thesis, University of California, Berkeley,
2001.

Stoichiometric Behavior of Cationic Silyl and Silylene Complexes
Organometallics, Vol. 21, No. 22, 2002 4653
selectivity is probably due to the fact that as a strong
π-acid, CO prefers coordination to the electron-rich Ir
center, while pyridine, a good σ donor like Et2O, prefers
to bind to the silicon center. Ethylene reacts with a
mixture of 16 and 17 like CO rather than pyridine,
leading to the silyl ethylene complex [Cp*(PMe3)Ir-
(SiMe3)(C2H4)][B(C6F5)4] (21) in 70% isolated yield as
pale yellow crystals. This appears to be the first reported
cationic silyl ethylene complex, and it provides circum-
stantial evidence for the existence of [Cp*(P(OMe)3)Co-
(SiEt3)(olefin)]+, a postulated intermediate in the cata-
lytic hydrosilylation of olefins by [Cp*(P(OMe)3)CoCH2-
CH2-µ-H]{B[3,5-(CF3)2C6H3]4}.29
lylation by 9 could involve insertion of the ketone into
the iridium-silyl bond of a putative [Cp*(PMe3)Ir-
(SiPh3)][B(C6F5)4] complex. When 5 mol % of cyclom-
etalated complex 9 is combined with acetophenone and
HSiPh3 at room temperature in CD2Cl2, formation of
the hydrosilylated product occurs in 27% yield after 24
h. Only one organometallic species is evident at this
time. This species was unambiguously identified as
[Cp*(PMe3)Ir(SiPh3)(H)2][B(C6F5)4] (14) by addition of
1
an authentic sample to the mixture and analysis by H
NMR spectroscopy. Surprisingly, when 14 was inde-
pendently prepared from 9 and dihydrogen (Scheme 1),
it was not an active catalyst for hydrosilylation of
acetophenone with triphenylsilane. This indicates that
the true catalyst must be present in a very small
amount and must be highly active. Further reaction of
the hydrosilylation mixture at 75 °C for 24 h leads to
an increase of the amount of hydrosilylated material
(50% overall) and formation of ethylbenzene in 19%
yield.
Ca ta lytic Stu d ies. Reduction of acetophenone with
H2SiPh2 in CD2Cl2 using 5 mol % [Cp*(PMe3)Ir(SiPh2)-
(H)][B(C6F5)4] (5) leads to formation of the corresponding
alkoxysilane in 54% yield after 18 h at 25 °C (eq 8).
The role of the weakly coordinating anion was probed
by examining triflate-stabilized silylene complexes as
catalysts for room temperature ketone hydrosilylation.
A catalyzed hydrosilylation was attempted by treating
acetophenone with diphenylsilane in CD2Cl2 in the
presence of 5 mol % Cp*(PMe3)Ir(SiPh2OTf)(H). No
reaction was observed after allowing the reaction mix-
ture to stand for 5 h. A small amount (30% against an
internal standard) of hydrosilylated product was ob-
served upon heating the mixture to 75 °C for 4 h. Under
these conditions, Cp*(PMe3)Ir(SiPh2OTf)(H) is converted
to an approximately 1:1:1 mixture of unidentified prod-
ucts. The low reactivity of the triflate suggests that
anion dissociation is crucial to catalyst activity.
The possibility that 1,2-hydride migration in [Cp*-
(PMe3)Ir(SiPh2)(H)][B(C6F5)4] (5) leads to catalyst de-
composition led us to synthesize and examine ruthe-
nium complexes of the type [Cp*(PMe3)2Ru(SiR2)][B-
(C6F5)4] (R ) thiolate, alkyl). A ruthenium silylene
complex bearing carbon substituents on silicon was
synthesized and examined first, as this should be a close
analogue of the iridium silylene complex 5. Heating a
toluene solution of Cp*(PMe3)2Ru(CH2SiMe3) and HSi-
(iPr)2Cl to 105° C for 5 h produced Cp*(PMe3)2Ru[Si-
(iPr)2Cl] (22) in 76% yield as yellow crystals after
recrystallization from Et2O at -35 °C. Related ruthe-
nium complexes have been previously synthesized.28
Chlorosilyl derivative 22 was converted to the corre-
sponding silylene complex [Cp*(PMe3)2Ru(SiiPr2)]-
[B(C6F5)4] (23) in 94% isolated yield by treatment with
(Et2O)2LiB(C6F5)4 (eq 9). Ruthenium silylene complex
Ethylbenzene, the product of overreduction, was de-
tected in 20% yield. Although it is not very common,
overreduction of acetophenone has been observed previ-
ously in other hydrosilation reactions.41 Acetone could
be reduced under similar conditions, with formation of
Ph2Si(H)(OiPr) occurring in 33% yield after 3 h. The
major product formed in this reaction is Ph2Si(OiPr)2
(40% yield), formed from further reaction of Ph2Si(H)-
(OiPr) with acetone. The remaining unreacted H2SiPh2
(27%) was spectroscopically observed. Monitoring the
reaction mixture after 5 min by 31P NMR spectroscopy
at room temperature indicates complete conversion of
5 to a mixture of products. It was not possible to
determine the resting state of the catalyst due to the
number of different organometallic species present in
solution.
The success of using silylene complex 5 as a precata-
lyst in room temperature reductions of ketones led us
to investigate the catalytic properties of another Ir(III)
silylene complex. The more sterically hindered silylene
complex [Cp*(PMe3)Ir(SiMes2)(H)][OTf] (4) offered the
possibility of stabilization against catalyst decomposi-
tion. However, when 5 mol % of 4 was combined with
acetophenone and diphenylsilane no productive hydrosi-
lylation was observed after 3 d at room temperature.
At that time, the 31P NMR spectrum indicated the
presence of at least four organometallic complexes and
no 4.
The catalytic hydrosilylation activity of the cyclo-
metalated species [Cp*(PMe3)Ir(η2-SiPh2C6H4)(H)]-
[B(C6F5)4] (9) was studied because of its potential to
function in a fashion mechanistically similar to that of
5. As described previously, complex 9 has been shown
to readily undergo C-H reductive elimination in the
presence of added Lewis bases, and therefore hydrosi-
(39) Hollis, T. K.; Robinson, N. P.; Bosnich, B. Tetrahedron Lett.
1992, 33, 6423.
(40) Grumbine, S. K.; Straus, D. A.; Tilley, T. D.; Rheingold, A. L.
Polyhedron 1995, 14, 127.
(41) Parks, D. J .; Blackwell, J . M.; Piers, W. E. J . Org. Chem. 2000,
65, 3090.
23 exhibits a 29Si NMR resonance of +437.4 ppm, the
furthest downfield shift yet measured for a silylene
complex. This verifies the existence of a base-free three-

4654 Organometallics, Vol. 21, No. 22, 2002
Klei et al.
Ta ble 3. Com p a r ison of Hyd r osilyla tion Ca ta lysts
coordinate silicon center. Ruthenium silylene complex
23 was observed to undergo 22% decomposition to
multiple products after 16 h at room temperature. This
indicates a higher kinetic stability for 23 than for [Cp*-
(PMe3)2Ru(SiMe2)][B(C6F5)4], which is known to decom-
pose at room temperature with a half-life of 7 h.28
Employing [Cp*(PMe3)2Ru(SiiPr2)][B(C6F5)4] (23) as
a hydrosilylation catalyst for the reduction of acetophen-
one with diphenylsilane led to no detectable product
formation after 4 h at room temperature. Analysis of
the reaction mixture during and after the hydrosilyl-
ation catalysis indicated that silylene complex 23 was
converted to a number of unidentified organometallic
complexes. Interestingly, silylene complex 23 is a cata-
lytically active (5 mol %) precursor for the addition of
1-ethoxy-1-(trimethylsilyloxy)ethene to acetophenone, a
reaction catalyzed by Lewis acids.39 The addition prod-
uct is formed in 53% yield after 20 min. Unfortunately,
complete decomposition of the catalyst was also ob-
served after 20 min.
The thermal instability of silylene complex 23 and its
ready decomposition under catalytic conditions led us
to explore ruthenium silylene complexes with differing
substitution at silicon. Tilley and co-workers have
measured the activation parameters for acetonitrile
exchange in complexes of the type [Cp*(PMe3)2Ru(SiR2)-
(NCMe)][BPh4], and used these data to compare the
stabilization offered by various donor substituents at
silicon. It was found that the stability offered followed
the trend S(p-tolyl) > O(p-tolyl) > Me > Ph.40 This
suggested that employing thiolate substitution at silicon
might lead to a catalytically active silylene complex that
was more stable to the reaction conditions.
catalyst
R ) Me; R′ ) H R ) Ph; R′ ) H R ) Ph; R′ ) Ph
5
44
0
54
21
<10
>95
B(C6F5)3
hydrosilylation. The use of this borane for ketone
reductions has been reported recently.41 The combined
results for the hydrosilyation comparison are sum-
marized in Table 3. It can be seen that in reactions
catalyzed by 10 mol % B(C6F5)3, use of HSiPh3 leads to
an excellent yield (>95%) of the hydrosilylated product
for the reduction of acetophenone. In contrast, using H2-
SiPh2 as the reductant led to substantially lower yields
of hydrosilylated product for both acetophenone (21%)
and acetone (<5%). All reactions were carried out at
room temperature in CD2Cl2 for 6 h. Intriguingly, a
completely different reactivity pattern is observed with
5 mol % of silylene complex [Cp*(PMe3)Ir(SiPh2)(H)]-
[B(C6F5)4] (5) under otherwise identical conditions.
There it is found that using triphenylsilane as the
reductant leads to very little hydrosilylated product
(<10%), but diphenylsilane led to increased reactivity
for both acetophenone and acetone.
The possibility that iridium silylene complex 5 cata-
lyzes ketone hydrosilylation through a metal-centered
Lewis acid mechanism deserved further attention. This
was probed by using the corresponding methyliridium
complex Cp*(PMe3)Ir(Me)OTf (1) as a precatalyst. Study-
ing the hydrosilylation reactions in this context is not
feasible because reaction with the silane to produce the
corresponding silyliridium species is extremely rapid.
Therefore, another reaction commonly catalyzed by
Lewis acids, the addition of a silyl ketene acetal to a
ketone,39 was examined. When 5 mol % of methyliri-
dium complex 1 was combined with acetophenone and
1-ethoxy-1-(trimethylsilyloxy)ethene a 37% yield of the
addition product was detected after 20 min (eq 11).
Reaction of Cp*(PMe3)2Ru(CH2SiMe3) with HSi(SPh)3
at 105 °C for 6 h in benzene produces the silyl derivative
Cp*(PMe3)2Ru[Si(SPh)3] (24) in 64% isolated yield as
off-white crystals. Treatment of silyl complex 24 with
1.1 equiv of TMSOTf in benzene at 45 °C for 5 h led to
isolation of Cp*(PMe3)2Ru[Si(SPh)2OTf] (25) in 45%
yield. The pale yellow silyltriflate complex 25 could then
be treated with 1 equiv of Li(Et2O)2B(C6F5)4 in CH2Cl2
to afford the deep yellow silylene complex {Cp*(PMe3)2-
Ru[Si(SPh)2]}[B(C6F5)4] (26) in 83% isolated yield (eq
10). The 29Si NMR spectrum of 26 consists of one
Again, however, complete conversion of 1 to a complex
mixture of at least four new organometallic complexes
was observed by 31P NMR spectroscopy.
Discu ssion
resonance at 262.0 ppm, establishing the presence of a
three-coordinate silicon center. It was found that com-
bining 5 mol % of thiolate-substituted silylene complex
26 with acetophenone and diphenylsilane in CD2Cl2 led
to no observable ketone reduction after 20 min, and
<10% yield of the desired product after 12 h.
A direct comparison of [Cp*(PMe3)Ir(SiPh2)(H)][B-
(C6F5)4] (5) with B(C6F5)3 in hydrosilylation reactions
was made because these two compounds are both strong
electrophiles and may use a similar mechanism for
Stoich iom etr ic Rea ctivity. An insertion reaction
that may have relevance as a step in catalytic hydrosi-
lylation was discovered upon reaction of dimesitylsi-
lylene complex 4 with p-tolualdehyde to give cyclomet-
alated Ir(V) complex 6. This reaction is rapid (t1/2 < 5
min), and no intermediates are observed by H and 31P
1
NMR spectroscopy. One mechanism for the formation
of 6 involves a 1,2-hydride migration to produce an
iridium silyl complex (I), which is capable of inserting

Stoichiometric Behavior of Cationic Silyl and Silylene Complexes
Organometallics, Vol. 21, No. 22, 2002 4655
Sch em e 3
Sch em e 4
the aldehyde to form an Ir(III) alkyl complex (II) (Path
A in Scheme 3). This species can then react with the
pendant Si-H bond by oxidative addition, and then
reductive elimination from the iridium center will form
a new C-H bond and produce silyl intermediate III.
The observed product 6 is then formed by cyclometala-
tion of a silicon-bound mesityl group by oxidative
addition. An alternative mechanism involves a [2+2]
cycloaddition of the iridium silylene group with the
carbonyl functionality to produce intermediate IV (Path
B in Scheme 3). Carbon-hydrogen reductive elimination
would provide intermediate III (as in Path A), which
can then form the product as described. There is no
evidence at this time to favor either of the mecha-
nisms.42 It should be noted that the degree of double
bond character in late-metal silylene complexes such as
4 is predicted to be low,43,44 making the possibility of a
concerted [2+2] cycloaddition somewhat unlikely. In-
stead, reactions involving these polar metal-silicon
bonds with unsaturated substrates can be expected to
take place in two steps. In fact, there has been only one
report involving cycloaddition reactions of silylene
complexes, and evidence was presented that it proceeds
in a stepwise fashion.26
Similar mechanistic steps can be proposed for the
formation of pendant olefin complex 7 from diphenyl-
silylene complex 5 and 4-ethynyltoluene (eq 5). Again,
insertion and cycloaddition mechanisms are both pos-
sible for this transformation (Scheme 4). For the inser-
tion mechanism (Path A), a 1,2-hydride migration of 5
produces an iridium silyl intermediate that undergoes
insertion to form an iridium alkenyl species (V). Activa-
(42) A referee has suggested an alternative mechanism involving
coordination of p-tolualdehyde through its oxygen to the silylene ligand
of 4, followed by hydride migration to the carbonyl carbon of the
aldehyde to give intermediate III. We cannot rule out this possibility
on the basis of our observations at the present time.
(43) Cundari, T. R.; Gordon, M. S. J . Phys. Chem. 1993, 96, 631.
(44) Arnold, F. P. Organometallics 1999, 18, 4800.

4656 Organometallics, Vol. 21, No. 22, 2002
Klei et al.
Sch em e 5
tion of the Si-H bond by oxidative addition to produce
an Ir(V) intermediate (VI), followed by C-H reductive
elimination and olefin coordination, affords the observed
product. An alternative mechanism involves cycloaddi-
tion to form an iridacycle (VI, Path B), which is capable
of C-H reductive elimination to form an iridium silyl
complex. Olefin coordination then results in formation
of 7.
tion,14 this is the first report of such a process within
the coordination sphere of a transition metal.
Ca ta lytic Rea ctivity. Catalytic transformations in-
volving C-H bond activation and/or insertion at Ir(III)
centers are exceedingly rare. One example involves use
of [Cp*(PMe3)Ir(H)(CH2Cl2)][HB(C6F5)3] as a catalyst for
transferring deuterium from C6D6 to organic sub-
strates.46 Another is the more recent isotopic labeling
system comprised of Cp*(PMe3)IrCl2 and D2O.47 Smith
and co-workers recently reported an iridium-catalyzed
arene borylation method for which they propose an
Ir(III)/Ir(V) oxidation state couple.48 The slow develop-
ment of C-H functionalization processes based on Ir(III)
complexes is due in part to the reluctance of Ir(III) alkyl
complexes to undergo insertion reactions. For example,
once the â-H elimination products [Cp*(PMe3)Ir(R)-
(olefin)][X] are formed from C-H activation, neither
olefin dissociation nor insertion are observed as clean
reaction pathways.13 In fact, high barriers for olefin
insertion into the iridium-methyl bonds of [Cp(PH3)-
Ir(Me)]+ have been calculated.49,50 Since the complexes
described here have the potential to behave as 16-
electron Ir(III) silyl complexes, it was hoped that an
examination of the insertion reactivity of these species
would lead to a catalytic hydrosilylation processes
involving an Ir(III)/Ir(V) oxidation state couple.
The iridium silylene complexes tested for catalytic
hydrosilylation of ketones were clearly more active than
the ruthenium silylene complexes. Although this may
be due to a more readily accessed metal-mediated
“Chalk-Harrod” mechanism,14 the mixtures of organo-
metallic products that result from catalytic hydrosilyl-
ation initiated by both the silyliridium and silylruthe-
nium complexes have so far prevented extensive mecha-
nistic insight into the reactions. Another likely possi-
bility, Lewis acid catalysis that is either silicon- or
iridium-centered, is considered based on a report by
Piers and co-workers that the strong electrophile B(C6F5)3
can catalyze ketone hydrosilylation.41 Back-bonding in
transition metal silylene complexes is predicted to be
low.43,44 In the limit that there is no back-bonding, the
silylene complexes feature 6-electron silicon centers,
which are isoelectronic with boranes, and would there-
The observation that cyclometalated iridium complex
9 can cleave the carbon-carbon bond of alkyl and aryl
nitrile substrates follows closely the reactivity of the
isostructural rhodium complex [Cp*(PMe3)Rh(η2-SiPh2-
(C6H4))(H)][B(C6F5)4].37 The postulated mechanism for
nitrile cleavage can be seen in Scheme 5. It is likely that
after the silyliridium acetonitrile complex is produced,
C-C activation occurs to yield an iridium(V) species,
[Cp*(PMe3)Ir(SiPh3)(CN)(CH3)][B(C6F5)4]. Migration of
the silyl group to the nitrogen atom of the cyanide ligand
completes the mechanism. The iridium complexes re-
quire elevated temperatures for this transformation,
presumably because the acetonitrile ligand of the in-
termediate [Cp*(PMe3)Ir(NCMe)(SiPh3)][B(C6F5)4] is
more tightly bound in the third row transition metal
complex. As a possible mechanism for the reaction of 9
with p-tolualdehyde, we suggest it may begin by inser-
tion of the aldehyde into the Ir-Si bond to afford an
iridium alkyl complex, followed by cyclometalation of a
phenylsilicon C-H bond, alkyl C-H reductive elimina-
tion, and coordination of the oxygen to iridium to give
product 10.
Reactivity studies of the iridium silene complex 13
revealed an observable rearrangement to a cationic,
base-stabilized iridium silylene complex. Berry and co-
workers recently reported the first direct observation
of intramolecular activation (or â-hydrogen elimination)
of aliphatic C-H bonds in a 16-electron metal silyl
complex to generate a silene complex, showing that a
silene complex can be derived from a silyl complex.4,45
Likewise, it has been shown that observable base-free
silylene ligands may be derived from silyl ligands by
R-migration.28 Reactivity studies in the iridium system
described here provide evidence for a third type of
isomerization, involving silene and silylene ligands (eq
12). Whereas the free silene/silylene interconversion
(45) Berry, D. H.; Procopio, L. J . J . Am. Chem. Soc. 1989, 111, 4099.
(46) Golden, J . T.; Andersen, R. A.; Bergman, R. G. J . Am. Chem.
Soc. 2001, 123, 5837.
(47) Klei, S. R.; Golden, J . T.; Tilley, T. D.; Bergman, R. G. J . Am.
Chem. Soc. 2002, 124, 2092.
(48) Cho, J .-Y.; Tse, M. K.; Holmes, D.; Maleczka, R. E.; Smith, M.
R. Science 2002, 295, 305.
(49) Han, Y.; Deng, L.; Ziegler, T. J . Am. Chem. Soc. 1997, 119, 5939.
(50) Niu, S.; Zaric, S.; Bayse, C. A.; Strout, D. L.; Hall, M. B.
Organometallics 1998, 17, 5139.
between SiMe2 and H2CdSi(H)Me has been the topic
of considerable experimental and theoretical investiga-

Stoichiometric Behavior of Cationic Silyl and Silylene Complexes
Organometallics, Vol. 21, No. 22, 2002 4657
fore be referred to as metal-substituted silylium cations.
Note that three-coordinate silyl cations which are not
substituted by metal centers are very unstable,51 with
[Mes3Si][B(C6F5)4] being the only well-established ex-
ample.52 The silicon- and iridium-centered Lewis acidic
centers are interchanged by a 1,2-migration that is
known to be facile20 in this system (eq 13).
discovered dehydropolymerization of silanes to carbosi-
lanes appears to involve silene complexes.53 Also, con-
siderable speculation has centered on the potential role
of silylene complexes in the dehydrocoupling of silanes
to polysilanes, and Berry has presented convincing
evidence for participation of a germylene complex
formed via R-migration in the demethanitive coupling
of germanes to polygermanes.54 Clearly, an understand-
ing of the factors controlling the pathway for elimination
reactions in metal silyl derivatives (e.g., R vs â) are key
to development of catalytic reactions in these systems.
In this context, the observed interconversion of the
silene and silylene ligands is interesting in that it
provides information regarding factors that might be
used to control the course of reactions from a metal
silene/silylene equilibrium manifold.
Iridium silyl and silylene complexes are catalysts for
the hydrosilylation of ketones under mild conditions.
The formation of multiple organometallic products dur-
ing the catalysis made it difficult to study the mecha-
nism of these catalyses, however, and in one case it was
shown that the only detectable organometallic species
in solution was not catalytically active. The facile
decomposition of these silyliridium catalysts is a result
of the large number of different reaction pathways
available to them, including 1,2-migration to produce
silylene complexes and cyclometalation to give Ir(V)
complexes. If these complexes can be stabilized ef-
fectively against decomposition, an extension of this
work to include catalytic, enantioselective reductions
may be possible using chiral silylene complexes.
A direct comparison of the iridium silylene complexes
with B(C6F5)3 in hydrosilylation reactions offered an aid
to our understanding of the reaction mechanism. Inter-
estingly, it was found that catalysis by B(C6F5)3 was
substantially improved upon changing the reductant
from H2SiPh2 to HSiPh3. The iridium silylene complex
5 behaved in the opposite manner, with the less
substituted silane giving superior performance. The
results for borane catalysis can be interpreted upon
consideration of the hydrosilylation mechanism ad-
vanced by Piers and co-workers,41 which invokes an
intermediate with positive charge buildup on silicon (eq
14). Such an intermediate would be more stabilized
Exp er im en ta l Section
Gen er a l P r oced u r es. Unless otherwise noted, reactions
and manipulations were performed at 25 °C in an inert
atmosphere (N2) glovebox or with standard Schlenk and high
vacuum or pressure techniques. Glassware was dried for a
minimum of 12 h at temperatures of 150 °C or greater. All
NMR spectra were obtained on Bruker AMX-400, AMX-300,
and DRX-500 MHz spectrometers. The temperature for NMR
experiments was controlled with BVT-1000 or BVT-3000 units.
1H NMR chemical shifts (δ) are reported in parts per million
(ppm) relative to tetramethylsilane and referenced to residual
protiated solvent. Infrared (IR) spectra were recorded on a
Mattson Instruments Galaxy 3000 Fourier transform spec-
trometer, and samples were prepared as KBr pellets. Mass
spectrometric (MS) analyses were obtained at the University
of California, Berkeley mass spectrometry facility on Micro-
mass VG Quattro (equipped with ESI source), VT ProSpec,
ZAB2-Eq, and 70-FE mass spectrometers. Elemental analyses
were performed at the University of California, Berkeley
Microanalytical facility on a Perkin-Elmer 2400 Series II
CHNO/S Analyzer.
Sealed NMR tubes were prepared by attaching Cajon
adapters directly to Kontes vacuum stopcocks and flame
sealing. Reactions with gases and low-boiling liquids involved
condensation of a calculated pressure of gas from a bulb of
known volume into the reaction vessel at -196 °C. These
vacuum transfers were accomplished with a digital MKS
Baratron gauge attached to a high-vacuum line.
Ma ter ia ls. Unless otherwise noted, reagents were pur-
chases from commercial suppliers and used without further
purification. Celite (Aldrich) and alumina (Brockman I, Ald-
through resonance if the silicon center were substituted
by three, rather than two, phenyl rings. Although the
iridium results are most readily interpreted by using
steric arguments that would suggest reaction with a less
hindered silane is more feasible, distinguishing between
a metal-mediated and a Lewis acid mechanism appears
to be difficult.
Con clu sion
The reactivity of unsaturated organic substrates with
late metal silyl complexes has not been fully developed,
especially when compared to metal alkyl complexes.14
The studies described here offer new findings in the
stoichiometric reaction chemistry of Ir(III) silyl and
silylene complexes, which hopefully can be used to
develop new catalytic processes involving silanes. For
example, a nitrile cleavage reaction was also discovered
while studying the reactivity of silyliridium complexes.
In the course of these reactivity studies, subsequent
rearrangement of the initially formed insertion products
made it difficult to learn the details of the putative
insertion step.
The chemistry of metal complexes containing reactive
silicon-based fragments is believed to be highly relevant
to a number of catalytic processes. For example, a newly
(51) Reed, C. A. Acc. Chem. Res. 1998, 31, 325.
(52) (a) Lambert, J . B.; Zhao, Y. Angew. Chem., Int. Ed. 1997, 36,
400. (b) For an additional recently-published example, see: Kim, K.-
C.; Reed, C. A.; Elliott, D. W.; Mueller, L. J .; Tham, F.; Lin, L.; Lambert,
J . B. Science 2002, 825.
(53) Procopio, L. J .; Berry, D. H. J . Am. Chem. Soc. 1991, 113, 4039.
(54) Reichl, J . A.; Popoff, C. M.; Gallagher, L. A.; Remsen, E. E.;
Berry, D. H. J . Am. Chem. Soc. 1996, 118, 9430.

4658 Organometallics, Vol. 21, No. 22, 2002
Klei et al.
rich) were dried at 250 °C for 48 h under vacuum. Pentane,
hexanes, and benzene were passed through a column of
activated alumina (A2, 12 × 32, Purifry Co.) collected under
and sparged with N2 prior to use.55 Diethyl ether and tetrahy-
drofuran were distilled from sodium/benzophenone ketyl under
N2 and sparged with N2 prior to use. Dichloromethane (Fisher)
was either distilled from CaH2 (Aldrich) under N2 or passed
through a column of activated alumina and collected under
and sparged with N2 prior to use. Deuterated solvents (Cam-
bridge Isotope Laboratories) were purified by the same pro-
cedures used for their protiated analogues and vacuum
Ar-C), 137.9 (m, B(C6F5)), 136.4 (s, Ar-CH), 135.4 (s, Ar-C),
135.2 (s, Ar-CH), 131.5 (s, Ar-CH), 131.5 (s, Ar-C), 131.3 (s,
Ar-CH), 130.0 (s, Ar-CH), 129.9 (s, Ar-CH), 129.3 (s, Ar-CH),
129.0 (s, Ar-C), 128.3 (s, Ar-CH), 100.8 (d, J P-C ) 1.3 Hz, C5-
Me5), 66.3 (s, alkenyl-CH), 38.6 (s, alkenyl-CH), 21.4 (s, Ar-
Me), 19.5 (d, J P-C ) 42 Hz, PMe3), 9.31 (s, C5Me5). 31P{1H}
NMR (162 MHz) δ -46.2. 19F{1H} NMR (376 MHz) δ -133
(s), -164 (t, J B-F ) 19 Hz), -167 (s). 29Si NMR (INEPT, 99
MHz) -5.1 (d, J Si-P ) 15 Hz). 19F{1H} NMR (376 MHz) δ -133
(s), -164 (t, J B-F ) 19 Hz), -167 (s). IR 3016, 2919, 2149, 1642,
1512, 1459, 1380, 1275, 1098, 950, 773, 705, 488 cm-1. Anal.
Calcd for C58H43PIrSiBF20: C, 50.41; H, 3.14. Found: C, 50.14,
H, 2.98.
56
transferred prior to use. Cp*(PMe3)2RuCH2SiMe3 and Cp*-
(PMe3)Ir(Me)OTf 11 were made according to literature proce-
dures. The Boulder Scientific Company is our supplier of
(Et2O)2LiB(C6F5)4.
Cp *(P Me3)[SiP h 2N(SiMe3)2]H (8). To a vial containing 4
mL of a CH2Cl2 solution of Cp*(PMe3)Ir(Me)OTf (98.9 mg,
0.174 mmol) was added H2SiPh2 (32.4 µL, 0.174 mmol) by
syringe. After the resulting yellow solution was manually
agitated for 10 s, the solvent was removed in vacuo. The
residue was dissolved in 3 mL of THF and to this was added
a THF (2 mL) solution of KN(TMS)2 (34.8 mg, 0.174 mmol).
The color of the solution changed to a dark amber yellow and
the solution was allowed to stand for 5 min. The solvent was
then removed in vacuo, producing a light brown residue, which
was extracted with pentane (3 × 2 mL). The extracts were
filtered through a fiberglass plug, and the filtrate solvent
removed in vacuo. The resulting oil was redissolved in 2 mL
of pentane and filtered through a plug (2 cm × 0.5 cm) of
silanized silica gel, and the plug was washed with 2 × 2 mL
of fresh pentane. The filtrate was removed in vacuo to afford
99.3 mg of a light amber oil (0.133 mmol, 76%). Material
{Cp*(P Me3)Ir (H)[K2-Si(2-CH2-3,5-(CH3)2C6H2)(Mes)(OCH2-
(p-tolyl))]}[OTf] (6). A solution of Cp*(PMe3)Ir(Me)OTf (120
mg, 0.212 mmol) in 5 mL of CH2Cl2 was pipetted into a vial
containing solid H2SiMes2 (56.8 mg, 0.212 mmol) and a
magnetic stir bar. This solution was stirred for 24 h, and then
p-tolualdehyde (24.9 µL, 0.212 mmol) was added by syringe.
The solution was stirred an additional 30 min, and the solvent
was then removed in vacuo. This afforded 169 mg (0.180 mmol,
1
85%) of 6 as an analytically pure yellow foam. H NMR (500
MHz) δ 7.16 (s, 1H, Ar-H), 7.09 (m, 4H, Ar-H), 6.97 (s, 1H,
Ar-H), 6.87 (s, 1H, Ar-H), 6.82 (s, 1H, Ar-H), 4.83 (d, J H-H
)
12 Hz, 1H, diastereotopic OCH2Ar), 4.43 (d, J H-H ) 12 Hz,
1H, diastereotopic O-CH2Ar), 3.49 (d, J H-H ) 14 Hz, 1H,
diastereotopic Ir-CH2), 2.90 (vt, J H-H ) 14 Hz, 1H, diaste-
reotopic Ir-CH2), 2.74 (s, 3H, Ar-Me), 2.34 (s, 3H, Ar-Me), 2.30
(m, 9H, overlapping Ar-Me), 1.75 (s, 3H, Ar-Me), 1.67 (d, J P-H
) 1.6 Hz, 15H, C5Me5), 1.45 (d, J P-H ) 11 Hz, 9H, PMe3), -14.7
(d, J P-H ) 20 Hz, 1H, Ir-H). 13C{1H} NMR (126 MHz) (the CF3
group was not detectable within a reasonable number of scans)
δ 152.9 (s, Ar-C), 145.0 (s, Ar-C), 144.3 (s, Ar-C), 142.3 (s, Ar-
C), 140.9 (s, Ar-C), 140.8 (s, Ar-C), 139.7 (s, Ar-C), 137.7 (s,
Ar-C), 137.1 (s, Ar-C), 130.4 (s, Ar-CH), 130.2 (s, Ar-CH), 129.5
(s, Ar-CH), 129.0 (s, Ar-CH), 127.5 (s, Ar-CH), 104.4 (d, J P-C
) 1.3 Hz, C5Me5), 67.8 (s, OCH2Ar), 25.0 (s, Ar-Me), 23.7 (s,
Ar-Me), 23.0 (s, Ar-Me), 21.3 (s, Ar-Me), 21.3 (s, Ar-Me), 16.7
(d, J P-C ) 43 Hz, PMe3), 13.0 (d, J P-C ) 10 Hz, Ir-CH2), 8.9 (s,
C5Me5). 31P{1H} NMR (162 MHz) δ -33.4. 29Si NMR (INEPT,
99 MHz) 32.9 (d, J Si-P ) 14 Hz). 19F{1H} NMR (376 MHz) δ
-77.0. IR 2980, 2871, 2920, 2163 (Ir-H), 1601, 1452, 1274,
1154, 1078, 1032, 949, 854, 799, 745, 637 cm-1. Anal. Calcd
for C40H55PIrSiO4SF3: C, 51.10; H, 5.90. Found: C, 51.37, H,
6.13.
1
obtained in this fashion is 80% pure by H NMR integration
of the product resonances against those of an internal stan-
dard. Conditions could not be found to induce crystallization,
1
and satisfactory elemental analysis could not be obtained. H
NMR (500 MHz) δ 7.61 (d, J P-H ) 7 Hz, 4 H, Ar-H), 7.24 (m,
6H, Ar-H), 1.75 (s, 15 H, C5Me5), 1.48 (d, J P-H ) 10 Hz, PMe3),
0.083 (s, 18 H, SiMe3), -18.1 (d, J P-H ) 28 Hz, Ir-H). 13C{1H}
NMR (126 MHz) δ 146.4 (s, Ar-C), 145.4 (s, Ar-C), 135.5 (s,
Ar-CH), 135.3 (s, Ar-CH), 126.8 (s, Ar-CH), 126.8 (s, Ar-CH),
126.4 (s, Ar-CH), 126.4 (s, Ar-CH), 94.2 (d, J P-C ) 3 Hz, C5-
Me5), 22.4 (d, J P-C ) 38 Hz, PMe3), 10.1 (s, C5Me5), 1.8 (s,
SiMe3). 31P{1H} NMR (162 MHz) δ -50.9. 29Si NMR (INEPT,
99 MHz) δ 3.9. IR 3050, 2966, 2919, 2861, 2128 (Ir-H), 1477,
1426, 1379, 1254, 1105, 1027, 953, 835, 738, 679, 531, 491,
442 cm-1
.
[Cp *(P Me3)Ir (Me)(CNSiP h 3)][OTf] (11b). A solution of
Cp*(PMe3)Ir(Me)OTf (91.2 mg, 0.161 mmol) in 4 mL of CH2-
Cl2 was added to a solution of HSiPh3 (41.9 mg, 0.161 mmol)
in 1 mL of CH2Cl2. To the resulting light yellow solution was
added acetonitrile (10.0 µL, 0.193 mmol) by syringe, and the
entire solution was then transferred to a 25-mL glass vessel
sealed to a Kontes vacuum adapter that contained a magnetic
stir bar. The stirred solution was heated to 75 °C for 24 h.
After cooling to room temperature, the reaction mixture was
transferred to a vial and the solvent was removed in vacuo.
An attempted recrystallization of the resulting pale yellow
foam from CH2Cl2/pentane at -35 °C yielded a light yellow
oil that was separated by removing the supernatant with a
pipet. This oil was triturated with Et2O (3 × 2 mL) to give
97.5 mg of a light yellow solid (0.114 mmol, 71%). 1H NMR
(500 MHz) δ 7.61 (m, 8H, Ar-H), 7.53 (m, 7H, Ar-H), 1.86 (d,
J P-H ) 2 Hz, 15H, C5Me5), 1.47 (d, J P-H ) 11 Hz, 9H, PMe3),
0.44 (d, J P-H ) 7 Hz, 3H, Ir-Me). 13C{1H} NMR (126 MHz) δ
151.9 (d, J P-C ) 14 Hz, Ir-CNSiPh3), 135.4 (s, Ar-CH), 132.4
(s, Ar-CH), 129.7 (s, Ar-C), 129.2 (s, Ar-CH), 99.5 (d, J P-C ) 3
Hz, C5Me5), 15.4 (d, J P-C ) 41 Hz, PMe3), 9.3 (s, C5Me5), -26.2
(d, J P-C ) 8 Hz, Ir-Me). 31P{1H} NMR (162 MHz) δ -37.0. 29Si
NMR (INEPT, 99 MHz) δ -151.1. 19F{1H} NMR (376 MHz) δ
-77.0. IR 2961, 2917, 2057, 1429, 1291, 1230, 1160, 1117,
1029, 955, 857, 743, 709, 638, 516 cm-1. Satisfactory elemental
analysis could not be obtained, despite several attempts.
{Cp *(P Me3)Ir [SiP h 2(η2-CHCH(p-tolyl))]}[B(C6F 5)4] (7).
To a 1 mL CH2Cl2 solution of Cp*(PMe3)Ir(Me)OTf (1) (50.0
mg, 0.0881 mmol) was added H2SiPh2 (16.4 mL, 0.0881 mmol)
by syringe, and the solution mixed well with a pipet. This
solution was added to solid (Et2O)2LiB(C6F5)4 (73.5 mg, 0.0881
mmol). The resulting slurry was mixed for 30 s with a pipet,
and then filtered through fiberglass into a vial. The fiberglass
and solids were washed with an additional 1 mL of CH2Cl2.
To the filtrate was added 4-ethynyltoluene (11.2 mL, 0.0881
mmol) by syringe, and the reaction mixed with a pipet for 10
s. The reaction mixture was allowed to stand for 30 min, and
then the solvent was removed in vacuo. This afforded 116 mg
(0.0842 mmol, 95%) of 7 as an analytically pure pale yellow
1
foam. H NMR (500 MHz) δ 7.83 (m, 2H, Ar-H), 7.70 (d, J H-H
) 6.8 Hz, 2H, Ar-H), 7.15-7.50 (m, 10H, Ar-H), 5.29 (vt, J H-H
) 14 Hz, 1H, alkenyl), 3.52 (d, J H-H ) 15 Hz, 1H, alkenyl),
2.37 (s, 3H, Ar-Me), 1.42 (d, J P-H ) 9.8 Hz, 9H, PMe3), 1.38 (d,
J P-H ) 1.6 Hz, 15H, C5Me5). 13C{1H} NMR (126 MHz) δ 149.8
(m, B(C6F5)), 147.9 (m, B(C6F5)), 139.8 (m, B(C6F5)), 139.1 (s,
(55) Alaimo, P. J .; Peters, D. W.; Arnold, J .; Bergman, R. G. J . Chem.
Educ. 2001, 78, 64.
(56) Tilley, T. D.; Grubbs, R. H.; Bercaw, J . E. Organometallics 1984,
3, 274.

Stoichiometric Behavior of Cationic Silyl and Silylene Complexes
Organometallics, Vol. 21, No. 22, 2002 4659
[Cp *(P Me3)Ir (P h )(CNSiP h 3)][OTf] (12b). A solution of
Cp*(PMe3)Ir(Me)OTf (105.5 mg, 0.1859 mmol) in 4 mL of CH2-
Cl2 was added to a solution of HSiPh3 (48.4 mg, 0.186 mmol)
in 1 mL of CH2Cl2. To the resulting light yellow solution was
added benzonitrile (18.9 µL, 0.186 mmol) by syringe, and the
entire solution was transferred to a 25-mL glass vessel sealed
to a Kontes vacuum adapter that contained a magnetic stir
bar. The stirred solution was heated to 45 °C for 5 h. After
cooling to room temperature, the reaction mixture was trans-
ferred to a vial and the solvent was removed in vacuo. The
resulting pale yellow foam was recrystallized at -35 °C from
CH2Cl2/pentane to give a single crop of off-white crystals (95.0
mg, 0.104 mmol) in 56% yield. 1H NMR (500 MHz) δ 7.62-
oil was dried in vacuo, producing 181 mg (0.135 mmol, 87%)
of 14 as an analytically pure off-white foam. 1H NMR (500
MHz) δ 7.64 (m, 6H, Ar-H), 7.41 (m, 9H, Ar-H), 1.78 (s, 15 H,
C5Me5), 1.41 (d, J P-H ) 11 Hz, 9H, PMe3), -14.5 (d, J P-H ) 24
Hz, 2H, Ir-H). 13C{1H} NMR (126 MHz) δ 149.9 (m, B(C6F5),
138.0 (m, B(C6F5)), 137.7 (s, Ar-C), 136.7 (s, Ar-CH), 136.0 (m,
B(C6F5)), 130.5 (s, Ar-CH), 128.8 (s, Ar-CH), 124.0 (m, B(C6F5)),
103.1 (s, C5Me5), 20.2 (d, J P-C ) 44 Hz, PMe3), 9.2 (s, C5Me5).
31P{1H} NMR (162 MHz) δ -42.7. 29Si NMR (INEPT, 99 MHz)
δ -3.3. 19F{1H} NMR (376 MHz) δ -133 (s), -164 (t, J B-F
)
19 Hz), -167 (s). IR 3074, 3013, 2917, 2142 (Ir-H), 1642, 1510,
1490, 1382, 1275, 1098, 975, 861, 755, 684, 504 cm-1. Anal.
Calcd for C55H41PIrSiBF20: C, 49.15; H, 3.08. Found: C, 48.77;
H, 3.45.
7.71 (m, 9H, Ar-H), 7.54 (m, 6H, Ar-H), 7.20 (d, J H-H ) 8 Hz,
2H, Ar-H), 7.02 (t, J H-H ) 8 Hz, 2H, Ar-H), 6.96 (t, J H-H ) 8
Hz, 2H, Ar-H), 1.80 (d, J P-H ) 2 Hz, 15H, C5Me5), 1.42 (d, J P-H
) 11 Hz, 9H, PMe3). 13C{1H} NMR (126 MHz) δ 139.5 (s, Ar-
C), 135.0 (s, Ar-CH), 132.1 (s, Ar-CH), 129.2 (s, Ar-CH), 128.8
{C p *(P Me 3 )I r [K2 -(C 6 H 4 -2-S iP h 2 )(O C H 2 (p -t o ly l))]}-
[B(C6F 5)4] (15). To 1 mL of a CH2Cl2 solution of Cp*(PMe3)-
Ir(Me)OTf (1, 115 mg, 0.203 mmol) was added 2 mL of a
CH2Cl2 solution of HSiPh3 (52.8 mg, 0.203 mmol) in a 20-mL
scintillation vial. The resulting pale yellow solution was well
mixed with a pipet, and then was added to solid (Et2O)2LiB-
(C6F5)4 (169 mg, 0.203 mmol) in another vial. The resulting
yellow slurry was mixed for 30 s with a pipet, then filtered
through fiberglass into a 5-mL vial. To this was added
p-tolualdehyde (23.9 µL, 0.203 mmol) by syringe. The solution
was mixed with a pipet for 30 s and allowed to stand for 20
min. The solvent was removed in vacuo, leaving a light yellow
residue. The residue was dissolved in 1 mL of Et2O then eluted
through a pipet column (0.5 cm × 3 cm) of silanized silica gel
with Et2O, and the yellow band was collected. The solvent was
removed in vacuo and the resulting yellow residue was
recrystallized from Et2O/pentane, yielding 143 mg (0.0974
mmol, 48%) of analytically pure 15. 1H NMR (500 MHz) δ
7.15-7.58 (m, 15H, Ar-H), 6.95 (d, J H-H ) 8 Hz, 2H, Ar-H),
6.75 (d, J H-H ) 8 Hz, 2H, Ar-H), 5.55 (d, J H-H ) 12 Hz, 1H,
diastereotopic OCH2), 4.80 (d, J H-H ) 12 Hz, 1H, diastereotopic
OCH2), 2.23 (s, 3H, Ar-Me), 1.41 (d, J P-H ) 2 Hz, 15H, C5Me5),
1.23 (d, J P-H ) 10 Hz, 9H, PMe3). 13C{1H} NMR (126 MHz) δ
156.8 (d, J P-C ) 15 Hz, Ir-C), 149.9 (m, B(C6F5), 141.1 (s, Ar-
C), 139.7 (Ar-C), 138.0 (m, B(C6F5)), 137.1 (s, Ar-CH), 136.9
(s, Ar-CH), 136.2 (s, Ar-CH), 136.2 (s, Ar-CH), 136.0 (m,
B(C6F5)), 133.5 (s, Ar-C), 132.9 (s, Ar-C), 132.5 (s, Ar-C), 132.3
(s, Ar-CH), 131.9 (s, Ar-CH), 131.9 (s, Ar-CH), 130.2 (Ar-CH),
130.0 (s, Ar-CH), 129.3 (s, Ar-CH), 129.0 (s, Ar-CH), 124.0 (m,
B(C6F5)), 124.0 (s, Ar-CH), 95.5 (d, J P-C ) 3 Hz, C5Me5), 77.6
(s, OCH2), 21.3 (s, Ar-Me), 14.9 (d, J P-C ) 39 Hz, PMe3), 9.6
(s, C5Me5). 31P{1H} NMR (162 MHz) δ -23.4. 29Si NMR
(INEPT, 99 MHz) δ 14.0. 19F{1H} NMR (376 MHz) δ -133 (s),
-164 (t, J B-F ) 19 Hz), -167 (s). IR 3034, 2922, 2036, 1643,
1512, 1460, 1380, 1273, 1090, 1022, 978, 811, 756, 700, 582,
518, 479 cm-1. Anal. Calcd for C63H47PIrSiOBF20: C, 51.75; H,
3.24. Found: C, 51.35; H, 3.53.
(s, Ar-CH), 128.6 (s, Ar-C), 127.7 (s, Ar-CH), 125.5 (d, J P-C
)
16 Hz, Ir-C), 124.2 (s, Ar-CH), 100.4 (s, C5Me5), 15.1 (d, J P-C
) 43 Hz, PMe3), 8.9 (s, C5Me5). 31P{1H} NMR (162 MHz) δ
-35.8. 29Si NMR (INEPT, 99 MHz) -17.6. 19F{1H} NMR (376
MHz) δ -77.0. IR 3063, 2986, 2917, 2067 (C-N), 1570, 1428,
1366, 1274, 1201, 1156, 1031, 951, 858, 740, 705, 635, 512
cm-1. Anal. Calcd for C39H44PIrNSiO3SF3: C, 51.19; H, 4.85;
N, 1.53; S, 3.50. Found: C, 50.85; H, 4.68; N, 1.48; S, 3.81.
[Cp*(P Me3)Ir (SiP h 3)(CO)][B(C6F5)4] (13). To solid HSiPh3
(53.1 mg, 0.204 mmol) was added 5 mL of a CH2Cl2 solution
of Cp*(PMe3)Ir(Me)OTf (1) (116 mg, 0.204 mmol). The result-
ing pale yellow solution was mixed thoroughly with a pipet
for 20 s, then added to solid (Et2O)2LiB(C6F5)4 (170 mg, 0.204
mmol). The slurry produced was mixed for 10 s with a pipet,
then filtered through a Celite/fiberglass plug to give a golden
solution. This solution was diluted to a total volume of 10 mL
with added CH2Cl2 and transferred to a 50-mL glass vessel
sealed to a Kontes vacuum adapter. The solution was degassed
and placed under CO (1 atm). The solution was stirred for 24
h and the solvent was removed in vacuo. Attempted crystal-
lization from CH2Cl2/pentane at -35 °C produced a light yellow
oil that was isolated by decanting the supernatant and
washing with 2 mL of fresh pentane. The oil was dried in
vacuo, producing 232 mg (0.169 mmol, 83%) of 13 as an
analytically pure off-white foam. 1H NMR (500 MHz) δ 7.54
(m, 6H, Ar-H), 7.41 (m, 9H, Ar-H), 1.79 (d, J P-H ) 2 Hz, 15 H,
C5Me5), 1.41 (d, J P-H ) 11 Hz, 9H, PMe3). 13C{1H} NMR (126
MHz) δ 169.3 (d, J P-C ) 11 Hz, Ir-CO), 149.9 (m, B(C6F5), 138.0
(m, B(C6F5)), 137.2 (s, Ar-CH), 136.8 (s, Ar-C), 136.0 (m,
B(C6F5)), 129.8 (s, Ar-CH), 128.0 (s, Ar-CH), 124.0 (m, B(C6F5)),
104.9 (d, J P-C ) 2 Hz, C5Me5), 18.1 (d, J P-C ) 42 Hz, PMe3),
9.2 (s, C5Me5). 31P{1H} NMR (162 MHz) δ -49.2. 29Si NMR
(INEPT, 99 MHz) δ -7.5. 19F{1H} NMR (376 MHz) δ -133
(s), -164 (t, J B-F ) 19 Hz), -167 (s). IR 3073, 3015, 2964, 2920,
2029 (Ir-CO), 1643, 1512, 1480, 1275, 1087, 972, 773, 704,
661, 496 cm-1. Anal. Calcd for C56H39PIrSiOBF20: C, 49.10;
H, 2.87. Found: C, 48.94, H, 3.09.
[Cp *(P Me3)Ir (SiMe2(p y))(Me)][B(C6F 5)4] (18). A 50-mL
glass vessel sealed to a Kontes vacuum adapter was charged
with 5 mL of a CH2Cl2 solution of Cp*(PMe3)Ir(Me)OTf (147.7
mg, 0.2603 mmol). The vessel was then degassed with 3
freeze-pump-thaw cycles. Into the vessel was condensed
HSiMe3 (74 Torr, 0.26 mmol) at -196 °C, using a bulb of
known volume (66 mL). The vessel was then warmed to 25
°C, and the solvent was removed in vacuo to afford Cp*-
(PMe3)Ir(SiMe2OTf)(Me) as a light yellow oil. This oil (134 mg,
0.214 mmol) was dissolved in 4 mL of CH2Cl2 and pipetted
onto solid (Et2O)2LiB(C6F5)4 (179 mg, 0.214 mmol). The result-
ing light yellow slurry was agitated with a pipet for 20 s and
then filtered through a fiberglass plug. Pyridine (17.3 mL,
0.214 mmol) was then added to the filtrate. After the reaction
mixture was allowed to stand for 5 min, the solution was
concentrated to 2 mL, and then Et2O was added until
precipitation occurred. The slurry was then filtered through
a fiberglass plug and stored at -35 °C for 36 h. Yellow crystals
(69 mg) were then isolated by removing the mother liquors
[Cp *(P Me3)Ir (SiP h 3)(H)2][B(C6F 5)4] (14). To solid HSiPh3
(40.3 mg, 0.155 mmol) was added a 5 mL CH2Cl2 solution of
Cp*(PMe3)Ir(Me)OTf (1) (87.9 mg, 0.155 mmol). A pipet was
used to mix the resulting pale yellow solution thoroughly for
20 s, followed by addition of the reaction mixture to solid
(Et2O)2LiB(C6F5)4 (131 mg, 0.155 mmol). The slurry produced
was mixed for 10 s with a pipet and filtered through a Celite/
fiberglass plug to give a golden solution. This solution was
diluted to a total volume of 10 mL with fresh CH2Cl2 and
transferred to a 50-mL glass vessel sealed to a Kontes vacuum
adapter. Three freeze-pump-thaw cycles were used to degas
the solution, which was then placed under H2 (1 atm). The
solution was stirred for 24 h and the solvent was removed in
vacuo. Attempted crystallization from CH2Cl2/pentane at -35
°C produced a light yellow oil that was isolated by decanting
the supernatant and washing with 2 mL of fresh pentane. The

4660 Organometallics, Vol. 21, No. 22, 2002
Klei et al.
with a pipet, washing the crystals with 3 mL of pentane, and
drying in vacuo. A second crop of crystals was grown by
concentrating the mother liquors to 1 mL in vacuo, adding
Et2O until precipition occurred, filtering the slurry through a
fiberglass plug, and storing the resulting solution at -35 °C
for 36 h. The combined yield of analytically pure yellow
crystals from the two crops was 200 mg (0.162 mmol, 75%).
MHz) δ 168.9 (s, CO), 149 (m, B(C6F5), 139 (m, B(C6F5)), 136
(m, B(C6F5)), 124 (m, B(C6F5)), 104.6 (s, C5Me5), 19.0 (d, J P-C
) 41 Hz, PMe3), 10.4(s, C5Me5), 6.1(s, SiMe3). 31P{1H} NMR
(162 MHz) δ -49.4 (s). 19F{1H} NMR (376 MHz) δ -133 (s),
-164 (t, J B-F ) 19 Hz), -167 (s). 29Si{1H} NMR INEPT (99
MHz) δ -1.2 (d, J P-Si ) 9.4 Hz). IR 2981, 2018, 1643, 1519,
1471, 1383, 1273, 1087, 1029, 985, 955, 833, 772, 662. Anal.
Calcd for C41H33BF20IrOPSi: C, 41.60; H, 2.81. Found: C,
41.50; H, 2.98.
3
1H NMR (400 MHz) δ 8.67 (d, J ) 5.2 Hz), 2H, py), 8.36 (t,
J H-H ) 7.5 Hz, 1H, py), 7.95 (t, J H-H ) 7.0 Hz, 2H, py), 1.58
(d, J P-H ) 1.7 Hz, 15 H, C5Me5), 1.50 (d, J P-H ) 9.6 Hz, 9 H,
[Cp *(P Me3)Ir (SiMe3)(C2H 4)][B(C6F 5)4] (21). To solid
(Et2O)2LiB(C6F5)4 (0.126 mg, 0.151 mmol) was added 10 mL
of a CH2Cl2 solution of Cp*(PMe3)Ir(Me)OTf (94.4 mg, 0.151
mmol). The resulting pale yellow slurry was mixed for 20 s
with a pipet and filtered through a fiberglass plug. The filtrate
was transferred to a 50-mL glass vessel sealed to a Kontes
vacuum adapter and degassed with 3 freeze-pump-thaw
cycles. Ethylene (43 Torr, 0.15 mmol) was condensed into the
vessel at -196 °C, using a bulb of known volume (66 mL). The
flask was allowed to warm to 25 °C, and was then shaken
vigorously for 30 s. After the reaction mixture was allowed to
sit for 15 min, the contents of the vessel were transferred to a
vial and reduced in volume to 1 mL in vacuo. Pentane was
added dropwise until precipitation occurred, and then CH2-
Cl2 was added until the solution was again homogeneous. Et2O
(1 mL) was added, and the solution was filtered through a
fiberglass plug. The filtrate was stored at -35 °C for 15 h,
and the mother liquors were removed with a pipet. The
crystals were washed with 2 mLof pentane, and this pentane
was then added to the mother liquors. The remaining solvent
was then removed in vacuo. A second crop of crystals was
grown by cooling the mother liquors to -35 °C for 24 h, and
isolated as described for the first crop. The combined yield of
the crops of analytically pure off-white crystals was 126 mg
PMe3), 0.74 (s, 3H, Si-Me), 0.53 (s, 3H, Si-Me), 0.26 (d, J P-H
)
6.3 Hz, 3H, Ir-Me). 13C{1H} NMR (126 MHz) δ 149 (m, B(C6F5),
146.3 (s, py), 144.1 (s, py), 139 (m, B(C6F5)), 136 (m, B(C6F5)),
124 (m, B(C6F5)),127.2 (s, py), 96.5 (s, C5Me5), 18.1 (d, J P-C
)
40 Hz, PMe3), 9.3(C5Me5), 7.4 (s, Si-Me), 6.7 (s, Si-Me), -10.1
(d, J P-C ) 8.8 Hz, Ir-Me). 31P NMR (162 MHz) δ -44.3 (s). 19F
NMR (376 MHz) δ -133 (s), -164 (t, J B-F ) 19 Hz), -167 (s).
29Si NMR (99 MHz) δ 49.0 (d, J P-Si ) 20 Hz). IR 2924, 1643,
1514, 1466, 1277, 1085, 979, 956, 833, 792, 770, 755, 682, 660.
Anal. Calcd for C45H38F20IrNPSi: C, 43.77; H, 3.10; N, 1.13.
Found: C, 43.73; H, 3.04; N, 1.09.
[Cp *(P Me3)Ir (SiMe2(p y))(Me)][OTf] (19). A 20-mL scin-
tillation vial was charged with 2 mL of a CH2Cl2 solution of
Cp*(PMe3)Ir(SiMe2OTf)(Me) (41.3 mg, 0.0660 mmol) and a
magnetic stir bar. To this stirred solution was added pyridine
(8.0 mL, 0.990 mmol) by syringe, and the reaction mixture was
stirred for 90 min. The volatile materials were removed in
vacuo and the resulting foam washed with 1:1 Et2O/pentane
(2 × 5 mL). The product was then dried in vacuo, affording
45.4 mg (0.647 mmol, 98%) of 19 as an analytically pure yellow
oil. 1H NMR (400 MHz) δ 8.67 (d, J H-H ) 5.2 Hz, 2H, py), 8.36
(t, J H-H ) 7.5 Hz, 1H, py), 7.95 (t, J H-H ) 7.0 Hz, 2H, py),
1.58 (d, J P-H ) 1.7 Hz, 15H, C5Me5), 1.50 (d, J P-H ) 9.6 Hz,
9H, PMe3), 0.74 (s, 3H, Si-Me), 0.53 (s, 3H, Si-Me), 0.26 (d,
J P-H ) 6.3 Hz, 3H, Ir-Me). 13C{1H} NMR (126 MHz) δ 146.3
(s, py), 144.4 (s, py), 127.5 (s, py), 96.3 (s, C5Me5), 18.1 (d, J P-C
) 40 Hz, PMe3), 9.3(s, C5Me5), 7.4 (s, Si-Me), 6.5 (s, Si-Me),
-10.1 (d, J P-C ) 8.8 Hz, Ir-Me). 31P{1H} NMR (162 MHz) δ
-44.3 (s). 19F{1H} NMR (376 MHz): δ -78.9 (s). 29Si{1H} NMR
(99 MHz) δ 49.0 (d, J P-Si ) 20 Hz). IR 2923, 1780, 1646, 1599,
1448, 1320, 1259, 1025, 697. Anal. Calcd for C22H38F3IrNPO3-
SSi: C, 37.49; H, 5.43; N, 1.99. Found: C, 37.62; H, 5.77; N,
1.64.
1
(0.106 mmol, 70%). H NMR (400 MHz) δ 2.20 (br, 2H, C2H4),
1.90, (br, 2H, C2H4), 1.74 (d, J P-H ) 2 Hz, 15H, C5Me5), 1.40
(d, J P-H ) 12 Hz, 9H, PMe3), 0.36 (s, 3H, SiMe3). 13C{1H} NMR
(126 MHz) δ 149 (m, B(C6F5), 139 (m, B(C6F5)), 136 (m,
B(C6F5)), 124 (m, B(C6F5)), 101.9 (s, C5Me5), 37.0, (br, C2H4),
16.1 (d, J P-C ) 41 Hz, PMe3), 9.3 (s, C5Me5), 5.7 (s, SiMe3).
31P{1H} NMR (162 MHz) δ -41.2 (s). 19F{1H} NMR (376 MHz)
δ -133 (s), -164 (t, J B-F ) 19 Hz), -167 (s). 29Si{1H} NMR
INEPT (99 MHz) δ -3.8 (d, J P-Si ) 9.4 Hz). IR 1644, 1514,
1464, 1405, 1274, 1093, 980. Anal. Calcd for C42H37BF20IrPSi:
C, 42.61; H, 3.15. Found: C, 42.28; H, 3.46.
[Cp *(P Me3)Ir (SiMe3)(CO)][B(C6F 5)4] (20). A 50-mL glass
vessel sealed to a Kontes vacuum adapter was charged with 5
mL of a CH2Cl2 solution of Cp*(PMe3)Ir(Me)OTf (119.5 mg,
0.2106 mmol). The vessel was then degassed with 3 freeze-
pump-thaw cycles. Into the vessel was condensed HSiMe3 (59
Torr, 0.21 mmol) at -196 °C, using a bulb of known volume
(66 mL). The vessel was then warmed to 25 °C, and the
resulting solution was pipetted onto solid (Et2O)2LiB(C6F5)4
(175.7 mg, 0.2106 mmol). The slurry produced in this manner
was mixed for 20 s with a pipet and then filtered through
fiberglass into another 50-mL glass vessel sealed to a Kontes
vacuum adapter that contained a magnetic stir bar. This vessel
was degassed with 3 freeze-pump-thaw cycles and filled with
1 atm of CO. The contents of the vessel were allowed to stir
for 24 h, transferred to a vial, and then reduced in volume to
1 mL in vacuo. Pentane was added until precipitation occurred,
and then CH2Cl2 was added until the solution was again
homogeneous. The resulting solution was filtered through a
fiberglass plug and cooled to -35 °C for 12 h. The supernatant
was removed with a pipet, and the crystals were washed with
3 mL of pentane and dried in vacuo. A second crop of crystals
was grown by concentrating the mother liquors, adding
pentane until precipitation occurred, filtering the solution
through a fiberglass plug, and cooling the resulting solution
to -35 °C for 24 h. The combined yield of analytically pure
off-white crystals was 172 mg (0.146 mmol, 69%). 1H NMR
(400 MHz) δ 2.10 (d, J P-H ) 2.1 Hz, 15H, C5Me5), 1.79 (d, J P-H
) 10.7 Hz, 9H, PMe3), 0.56 (s, 3H, SiMe3). 13C{1H} NMR (126
Cp *(P Me3)2Ru (SiiP r 2Cl) (22). A 50-mL glass vessel sealed
to a Kontes vacuum adapter containing a magnetic stir bar
was charged with 10 mL of a toluene solution of Cp*(PMe3)2-
Ru(CH2SiMe3) (300 mg, 0.631 mmol) and HSi(iPr)2Cl (108 µL,
0.631 mmol). The stirred solution was heated to 105 °C for 6
h. The solvent was then removed in vacuo, and a total of 3
crops of crystals were grown from concentrated Et2O solutions
at -35 °C. This afforded analytically pure yellow crystals of
22 in a combined yield of 257 mg (0.480 mmol, 76%). 1H NMR
i
(500 MHz) δ 1.55 (d, J P-C ) 1 Hz, C5Me5), 1.49 (s, 8H, Pr),
i
1.42 (d, J P-C ) 6 Hz, 6H, Pr), 1.21 (m, 18H, PMe3). 13C{1H}
NMR (126 MHz) δ 93.9 (s, C5Me5), 24.7 (dd, J P-C ) 13 Hz,
i
i
i
J P-C ) 15 Hz, PMe3), 23.2 (s, Pr), 22.9 (s, Pr), 20.2 (s, Pr),
12.6 (s, C5Me5). 31P{1H} NMR (162 MHz) δ 3.2. 29Si NMR
(INEPT, 99 MHz) δ 102.1. IR 2949, 2896, 2848, 1441, 1375,
1275, 1026, 943, 853, 702, 664, 608, 562, 478 cm-1. Anal. Calcd
for C22H47P2RuSiCl: C, 49.10; H, 8.80. Found: C, 49.19; H,
8.90.
[Cp *(P Me3)2Ru (SiiP r 2)]B(C6F 5)4] (23). A solution of Cp*-
(PMe3)2Ru(Si(iPr)2Cl) (22) (18.6 mg, 0.0346 mmol) in 1 mL of
CH2Cl2 was added to a vial containing solid (Et2O)2LiB(C6F5)4
(28.8 mg, 0.0346 mmol). The resulting slurry was filtered
through a fiberglass plug, and the plug was washed with 1
mL of fresh CH2Cl2 that was added to the filtrate. The solvent
was removed to afford 38.3 mg (0.0325 mmol, 94%) of 23 as
1
an analytically pure yellow foam. H NMR (500 MHz) δ 2.44
i
(septet, J H-H ) 7 Hz, Pr), 1.86 (s, 15 H, C5Me5), 1.53 (m, 18

Stoichiometric Behavior of Cationic Silyl and Silylene Complexes
Organometallics, Vol. 21, No. 22, 2002 4661
H, PMe3), 1.25 (d, J H-H ) 7 Hz, iPr). 13C{1H} NMR (126 MHz)
δ 149.9 (m, B(C6F5), 138.0 (m, B(C6F5)), 136.0 (m, B(C6F5)),
124.0 (m, B(C6F5)), 97.4 (s, C5Me5), 25.1 (dd, J P-C ) 15 Hz,
J P-C ) 17 Hz, PMe3), 17.4 (s, iPr), 15.6 (s, iPr), 12.0 (s, C5Me5).
31P{1H} NMR (162 MHz) δ 1.1. 29Si NMR (INEPT, 99 MHz) δ
437.4. 19F{1H} NMR (376 MHz) δ -133 (s), -164 (t, J B-F ) 19
Hz), -167 (s). IR 2942, 2868, 2140, 2103, 1643, 1514, 1442,
1382, 1278, 1089, 958, 854, 773, 684, 662, 611, 574 cm-1. Anal.
{1H} NMR (126 MHz) δ 149.9 (m, B(C6F5), 138.0 (m, B(C6F5)),
136.0 (m, B(C6F5)), 134.9 (s, Ar-CH), 130.8 (s, Ar-C), 130.3 (s,
Ar-CH), 129.7 (s, Ar-CH), 124.0 (m, B(C6F5)), 97.0 (s, C5Me5),
24.2 (m, PMe3), 11.6 (s, C5Me5). 31P{1H} NMR (162 MHz) δ
-2.9. 29Si NMR (INEPT, 99 MHz) δ 262.0. 19F{1H} NMR (376
MHz) δ -133 (s), -164 (t, J B-F ) 19 Hz), -167 (s). IR 2990,
2914, 1643, 1513, 1461, 1380, 1275, 1086, 979, 755, 684, 467
cm-1. Anal. Calcd for C52H43P2RuSiS2BF20: C, 47.54; H, 3.30.
Found: C, 47.21, H, 3.33.
Calcd for C46H47P2RuSiBF20
46.61, H, 4.09.
: C, 46.75; H, 4.01. Found: C,
Sa m p le P r oced u r e for Hyd r osilyla tion Ca ta lysis. All
silylene complexes were generated in situ under an inert
atmosphere at room temperature and used immediately. In
the case of iridium silylene complex 5, an external standard
(sealed in a capillary) of 1,3,5-trimethoxybenzene in C6D6 was
used as an integration reference. The internal standard used
for the other catalyses was 1,3,5-trimethoxybenzene. The
following is a sample protocol with [Cp*(PMe3)Ir(H)(SiPh2)]-
[B(C6F5)4]. A 5-mL vial was charged with Cp*(PMe3)Ir(Me)-
OTf (8.6 mg, 0.015 mmol) and 0.5 mL of CD2Cl2. To this
solution was added 2.8 µL (0.015 mmol) of H2SiPh2, and the
contents of the vial were mixed with a pipet. The reaction
mixture was pipetted onto solid (Et2O)2LiB(C6F5)4 (12.6 mg,
0.015 mmol), producing a light yellow slurry that was filtered
through a fiberglass plug after 20 s of agitation with a pipet.
This solution was transferred to a J . Young NMR tube, which
contained an external capillary standard of 1,3,5-trimethoxy-
benzene in C6D6, and a 1H NMR spectrum was acquired. To
this tube were added H2SiPh2 (56.3 µL, 0.303 mmol) and then
acetophenone (35.4 µL, 0.303 mmol), each by syringe. A 1H
NMR spectrum was immediately acquired and reaction progress
monitored periodically, with integrations of the hydrosilylation
product resonances made against resonances of the standard.
One-pulse spectra were acquired in all cases to ensure accurate
integration.
Cp *(P Me3)2Ru [Si(SP h )3] (24). A 50-mL glass vessel sealed
to a Kontes vacuum adapter containing a magnetic stir bar
was charged with a 10 mL toluene solution of Cp*(PMe3)2Ru-
(CH2SiMe3) (300 mg, 0.631 mmol) and HSi(SPh)3 (225 mg,
0.631 mmol). The stirred solution was heated to 105 °C for 6
h. The solvent was then removed in vacuo, and a single crop
of crystals was grown from a concentrated Et2O solution at
-35 °C. This afforded 300 mg (0.404 mmol, 64%) of 24 as
analytically pure pale yellow crystals. 1H NMR (500 MHz,
C6D6) δ 7.62 (dd, J H-H ) 2 Hz, J H-H ) 8 Hz, 6 H, SPh), 6.85
(m, 9H, SPh), 1.75 (s, 15 H, C5Me5), 1.25 (dd, J P-H ) 8 Hz,
J P-H ) 4 Hz, 9H, PMe3). 13C{1H} NMR (126 MHz, CD2Cl2) δ
138.4 (s, Ar-C), 134.5 (s, Ar-CH), 128.3 (s, Ar-CH), 125.6 (s,
Ar-CH), 95.7 (s, C5Me5), 24.5 (dd, J P-C ) 16 Hz, J P-C ) 13 Hz,
PMe3), 12.4 (s, C5Me5). 31P{1H} NMR (162 MHz, C6D6) δ 0.4.
29Si NMR (INEPT, 99 MHz, CD2Cl2) δ 48.8. IR 3045, 2980,
2912, 1578, 1475, 1434, 1279, 1066, 1024, 956, 851, 739, 688,
462 cm-1. Anal. Calcd for C34H48P2RuSiS3: C, 54.89; H, 6.50.
Found: C, 54.59, H, 6.45.
Cp *(P Me3)2Ru [Si(SP h )2OTf] (25). A 50-mL glass vessel
sealed to a Kontes vacuum adapter containing a magnetic stir
bar was charged with 10 mL of a toluene solution of Cp*-
(PMe3)2Ru(Si(SPh)3) (24) (275 mg, 0.370 mmol) and HSi(SPh)3
(73 µL, 0.407 mmol). The stirred solution was heated to 45 °C
for 12 h. The solvent was then removed in vacuo, and a single
crop of crystals was grown from a concentrated Et2O solution
at -35 °C. This afforded 124 mg (0.164 mmol, 45%) of 25 as
analytically pure pale yellow crystals. An attempt to grow a
second crop of crystals produced impure material. 1H NMR
(500 MHz) δ 7.48 (m, 4 H, SPh), 7.14 (m, 6 H, SPh), 1.86 (d,
J P-H ) 1 Hz, 15 H, C5Me5), 1.38 (m, 18 H, PMe3). 13C{1H} NMR
Ack n ow led gm en t. We thank Drs. Dana Caulder,
Allan Oliver, and Fred Hollander of the UC Berkeley
X-ray Diffraction Facility (CHEXRAY) for determination
of the crystal structures of 10 and 11a and Drs. J . S.
Yeston, D. M. Tellers, and P. J . Alaimo for helpful
discussions. We also appreciate the willingness of Ms.
F. L. Taw and Prof. M. Brookhart to disclose their nitrile
C-C activation results prior to publication. S.R.K.
thanks the National Science Foundation for a graduate
fellowship. We are grateful for support of this work by
the Director, Office of Energy Research, Office of Basic
Energy Sciences, Chemical Sciences Division, U.S.
Department of Energy, under Contract No. DE-AC03-
76SF00098 (R.G.B.), and by the National Science Foun-
dation (T.D.T.).
(126 MHz) (the CF3 group was not detectable within
a
reasonable number of scans) δ 135.6 (s, Ar-CH), 134.8 (s, Ar-
C), 128.7 (s, Ar-CH), 127.0 (s, Ar-CH), 95.9 (s, C5Me5), 24.2
(dd, J P-C ) 15 Hz, J P-C ) 17 Hz, PMe3), 11.8 (s, C5Me5). 31P-
{1H} NMR (162 MHz) δ -0.9. 29Si NMR (INEPT, 99 MHz) δ
67.3. 19F{1H} NMR (376 MHz) δ -77.5. IR 1580, 1479, 1275,
1154, 1029, 946, 741, 638 cm-1. Anal. Calcd for C29H43P2-
RuSiS3O3F3: C, 44.43; H, 5.53. Found: C, 44.18, H, 5.39.
{Cp *(P Me3)2Ru [Si(SP h )2]}[B(C6F 5)4] (26). A solution of
Cp*(PMe3)2Ru(Si(SPh)2OTf) (25) (32.7 mg, 0.0433 mmol) in 0.5
mL of CD2Cl2 was added to a vial containing solid (Et2O)2LiB-
(C6F5)4 (36.1 mg, 0.0433 mmol). The resulting slurry was
filtered through a fiberglass plug. The solvent was removed
to afford 47.1 mg (0.0359 mmol, 83%) of 26 as an analytically
Su p p or tin g In for m a tion Ava ila ble: Procedures and
characterization data for all new compounds and X-ray
structural data for complexes 10 and 11a . This material is
available free of charge via the Internet at http://pubs.acs.org.
1
pure yellow foam. H NMR (500 MHz) δ 7.31 (m, 10H, SPh),
1.92 (d, J P-H ) 2 Hz, 15 H, C5Me5), 1.40 (m, 9 H, PMe3). 13C-
OM0203173