New cationic and zwitterionic Cp*M(κ2-P,S) complexes (M = Rh, Ir): Divergent reactivity pathways arising from alternative modes of ancillary ligand participation in substrate activation

Article abstract of DOI:10.1021/ja8062277

Treatment of 0.5 equiv of [Cp*IrCl₂]₂ with 1/3-P_iPr₂-2-S^tBu-indene afforded Cp*Ir(Cl)(κ²-3-PⁱPr₂-2-S-indene) (1) in 95% yield (Cp* = η⁵-C₅Me₅). Addition of AgOTf or LiB(C₆F₅)₄·2. 5OEt₂ to 1 gave [Cp*Ir(κ²-3-P ⁱPr₂-2-S-indene)]⁺X^- ([2] ⁺X^-; X = OTf, 78%; X = B(C₆F₅) ₄, 82%), which represent the first examples of isolable coordinatively unsaturated [Cp′Ir(κ²-P, S)] ⁺X^- complexes. Exposure of [2]⁺OTf^- to CO afforded [2·CO]⁺OTf^- in 91% yield, while treatment of [2]⁺B(C_eF₅)₄ ^- with PMe₃ generated [2·PMe₃] ⁺B(C₆F₅)₄^- in 94% yield. Treatment of 1 with K₂CO₃ in CH₃CN allowed for the isolation of the unusual adduct 3·CH₃CN (41% isolated yield), in which the CH₃CN bridges the Lewis acidic Cp*Ir and Lewis basic indenide fragments of the targeted coordinatively unsaturated zwitterion Cp*Ir(κ²-3-PⁱPr₂-2-S- indenide) (3). In contrast to the formation of [2·CO]⁺OTf ^-, exposure of 3·CH₃CN to CO did not afford 3·CO; instead, a clean 1:1 mixture of (κ²-3-P ⁱPr₂-2-S-indene)lr(CO)₂ (4) and 1,2,3,4-tetramethylfulvene was generated. Treatment of [2]⁺OTf ^- with Ph₂SiH₂ resulted in the net loss of Ph₂Si(OTf)H to give Cp*Ir(H)(κ²-3-P ⁱPr₂-2-S-indene) (5) in 44% yield. In contrast, treatment of [2]⁺B(C₆F₅)₄^- with Ph₂SiH₂ or Ph₂SiH₃ proceeded via H-Si addition across Ir-S to give the corresponding [Cp*Ir(H) (κ²-3-PⁱPr₂-2-S(SiHPhX)-indene)] ⁺B(C₆F₅)₄^- complexes 6a (X = Ph, 68%) or 6b (X = H, 77%), which feature a newly established S-Si linkage. Compound 6a was observed to effect net C-O bond cleavage in diethyl ether with net loss of Ph₂Si(OEt)H, affording [Cp*Ir(H) (κ²-3-PⁱPr₂-2-SEt-indene)] ⁺B(C₆F₅)₄^- (7) in 77% yield. Furthermore, 6a proved capable of transferring Ph₂SiH ₂ to acetophenone, with concomitant regeneration of [2] ⁺B(C₆F₅)₄^-; however, [2]⁺X^- did not prove to be effective ketone hydrosilylation catalysts. Treatment of 1/3-PⁱPr₂-2-S ^tBu-indene with 0.5 equiv of [Cp*RhCl₂]₂ gave Cp*Rh(Cl)(κ²-3-PⁱPr₂-2-S- indene) (8) in 94% yield. Combination of 8 and LiB(C₆F ₅)₄-2.5Et₂O produced the coordinatively unsaturated cation [Cp*Rh(κ²-3-PⁱPr ₂-2-S-indene)]⁺B(C₆F₅) ₄^- ([9]⁺B(C₆F₅) ₄^-), which was transformed into [Cp*Rh(H) (κ²-3-PⁱPr₂-2-S(SiHPh₂)- indene)]⁺B(C₆F₅)₄^- (10) via net H-Si addition of Ph₂SiH₂ to Rh-S. Unlike [2] ⁺X^-, complex [9]⁺B(C₆F ₅)₄^- was shown to be an effective catalyst for ketone hydrosilylation. Treatment of 3·CH₃CN with Ph ₂SiH₂ resulted in the loss of CH₃CN, along with the formation of Cp*Ir(H)(κ²-3-PⁱPr ₂-2-S-(1-diphenylsilylindene)) (11) (64% isolated yield) as a mixture of diastereomers. The formation of 11 corresponds to heterolytic H-Si bond activation, involving net addition of H^- and Ph₂HSi ⁺ fragments to Ir and indenide in the unobserved zwitterion 3. Crystallographic data are provided for 1, [2·CO]⁺OTf ^-, 3·CH₃CN, 7, and 11. Collectively, these results demonstrate the versatility of donor-functionalized indene ancillary ligands in allowing for the selection of divergent metal-ligand cooperativity pathways (simply by ancillary ligand deprotonation) in the activation of small molecule substrates.

Full text of DOI:10.1021/ja8062277

Published on Web 11/06/2008
New Cationic and Zwitterionic Cp*M(K2-P,S) Complexes (M )
Rh, Ir): Divergent Reactivity Pathways Arising from
Alternative Modes of Ancillary Ligand Participation in
Substrate Activation
Kevin D. Hesp,† Robert McDonald,‡ Michael J. Ferguson,‡ and Mark Stradiotto*,†
Department of Chemistry, Dalhousie UniVersity, Halifax, NoVa Scotia B3H 4J3, Canada, and
X-ray Crystallography Laboratory, Department of Chemistry, UniVersity of Alberta, Edmonton,
Alberta T6G 2G2, Canada
Received August 7, 2008; E-mail: mark.stradiotto@dal.ca
Abstract: Treatment of 0.5 equiv of [Cp*IrCl2]2 with 1/3-PiPr2-2-StBu-indene afforded Cp*Ir(Cl)(κ2-3-PiPr2-
2-S-indene) (1) in 95% yield (Cp* ) η5-C5Me5). Addition of AgOTf or LiB(C6F5)4 ·2.5OEt2 to 1 gave [Cp*Ir(κ2-
3-PiPr2-2-S-indene)]+X- ([2]+X-; X ) OTf, 78%; X ) B(C6F5)4, 82%), which represent the first examples
of isolable coordinatively unsaturated [Cp′Ir(κ2-P,S)]+X- complexes. Exposure of [2]+OTf- to CO afforded
[2·CO]+OTf- in 91% yield, while treatment of [2]+B(C6F5)4- with PMe3 generated [2·PMe3]+B(C6F5)4- in
94% yield. Treatment of 1 with K2CO3 in CH3CN allowed for the isolation of the unusual adduct 3·CH3CN
(41% isolated yield), in which the CH3CN bridges the Lewis acidic Cp*Ir and Lewis basic indenide fragments
of the targeted coordinatively unsaturated zwitterion Cp*Ir(κ2-3-PiPr2-2-S-indenide) (3). In contrast to the
formation of [2·CO]+OTf-, exposure of 3·CH3CN to CO did not afford 3·CO; instead, a clean 1:1 mixture
of (κ2-3-PiPr2-2-S-indene)Ir(CO)2 (4) and 1,2,3,4-tetramethylfulvene was generated. Treatment of [2]+OTf-
with Ph2SiH2 resulted in the net loss of Ph2Si(OTf)H to give Cp*Ir(H)(κ2-3-PiPr2-2-S-indene) (5) in 44%
yield. In contrast, treatment of [2]+B(C6F5)4- with Ph2SiH2 or PhSiH3 proceeded via H-Si addition across
-
Ir-S to give the corresponding [Cp*Ir(H)(κ2-3-PiPr2-2-S(SiHPhX)-indene)]+B(C6F5)4 complexes 6a (X )
Ph, 68%) or 6b (X ) H, 77%), which feature a newly established S-Si linkage. Compound 6a was observed
to effect net C-O bond cleavage in diethyl ether with net loss of Ph2Si(OEt)H, affording [Cp*Ir(H)(κ2-3-
-
PiPr2-2-SEt-indene)]+B(C6F5)4 (7) in 77% yield. Furthermore, 6a proved capable of transferring Ph2SiH2
to acetophenone, with concomitant regeneration of [2]+B(C6F5)4-; however, [2]+X- did not prove to be
effective ketone hydrosilylation catalysts. Treatment of 1/3-PiPr2-2-StBu-indene with 0.5 equiv of [Cp*RhCl2]2
gave Cp*Rh(Cl)(κ2-3-PiPr2-2-S-indene) (8) in 94% yield. Combination of 8 and LiB(C6F5)4 ·2.5Et2O produced
the coordinatively unsaturated cation [Cp*Rh(κ2-3-PiPr2-2-S-indene)]+B(C6F5)4- ([9]+B(C6F5)4-), which was
transformed into [Cp*Rh(H)(κ2-3-PiPr2-2-S(SiHPh2)-indene)]+B(C6F5)4- (10) via net H-Si addition of Ph2SiH2
-
to Rh-S. Unlike [2]+X-, complex [9]+B(C6F5)4 was shown to be an effective catalyst for ketone
hydrosilylation. Treatment of 3·CH3CN with Ph2SiH2 resulted in the loss of CH3CN, along with the formation
of Cp*Ir(H)(κ2-3-PiPr2-2-S-(1-diphenylsilylindene)) (11) (64% isolated yield) as a mixture of diastereomers.
The formation of 11 corresponds to heterolytic H-Si bond activation, involving net addition of H- and
Ph2HSi+ fragments to Ir and indenide in the unobserved zwitterion 3. Crystallographic data are provided
for 1, [2·CO]+OTf-, 3·CH3CN, 7, and 11. Collectively, these results demonstrate the versatility of donor-
functionalized indene ancillary ligands in allowing for the selection of divergent metal-ligand cooperativity
pathways (simply by ancillary ligand deprotonation) in the activation of small molecule substrates.
exploited widely.1 In moving beyond these more traditional
design approaches, important reactivity breakthroughs have been
Introduction
Coordinatively unsaturated platinum-group metal (PGM)
complexes have long represented intriguing targets of inquiry,
owing to their extraordinary propensity for stoichiometric and
catalytic substrate activation.1 In an effort to control metal-
centered reactivity, the coordination of strategically constructed
ancillary ligands principally intended to tune the steric and
electronic properties of the metal coordination sphere has been
achieved through the development of PGM complexes that can
mediate challenging substrate transformations via cooperative
metal-ligand interactions in which the ancillary ligand is a
participant, rather than a spectator, in the substrate activation
process.2 The most widely studied class of PGM complexes
that exhibit such cooperative reactivity behavior are those pairing
a Lewis acidic metal fragment with a directly coordinated
† Dalhousie University.
‡ University of Alberta.
(2) For highlights of important developments in the metal-ligand
cooperative activation of substrates, see: Gru¨tzmacher, H. Angew.
Chem., Int. Ed. 2008, 47, 1814.
(1) Crabtree, R. H. The Organometallic Chemistry of the Transition
Metals; John Wiley and Sons: Hoboken, NJ, 2005.
9
16394 J. AM. CHEM. SOC. 2008, 130, 16394–16406
10.1021/ja8062277 CCC: $40.75
2008 American Chemical Society

Cp*M(κ2-P,S) Complexes
A R T I C L E S
Chart 1
nucleophilic/basic, nondative X-type ligand (X ) OR, NR2, or
other heteroatom-based fragment).2-4 It has been demonstrated
that the dual action of adjacent Lewis acidic (M) and Lewis
basic (X) fragments in such M-X systems can enable the
cooperative activation of a range of polar and nonpolar
substrates.3,4 Such PGM-amido species typify the mechanisti-
cally novel catalytic reactivity that can be accessed via M-X
cooperativity; appropriately designed complexes of this type
have been shown to mediate the catalytic hydrogenation and/
or transfer hydrogenation of polar bonds via outer-sphere
mechanisms involving the heterolytic splitting of H2 (or the net
extrusion of H2 from a donor-solvent) across an M-NHR unit
to give an (H)M-NH2R intermediate, which in turn can deliver
H2 to the substrate in a cooperative fashion.4 By comparison,
alternative modes of net metal-ligand cooperative substrate
activation involving a reactive PGM center and a noncoordi-
nating anionic portion of a bound ancillary ligand (referred to
herein as M∧X′ cooperativity) are rare. Nonetheless, the
examples documented thus far in the literature exemplify the
way in which M∧X′ cooperativity can provide access to unusual
stoichiometric and catalytic substrate activation pathways,
including the reversible 1,4-addition of ethylene and acetylene
to (arene)Ru(ꢀ-diketiminate) complexes,5,6 as well as the
dehydrogenation of alcohols into esters7a and the dehydroge-
native synthesis of amides from alcohols and amines7b mediated
by (κ3-P,N,N)Ru species.8 In the quest to uncover novel modes
of PGM-mediated substrate activation with potential applications
in catalysis, the development of versatile new classes of ancillary
ligands that can be modified easily so as to enable M-X and/
or M∧X′ cooperativity represents an important challenge.
In this context, we have reported details of comparative
reactivity studies featuring structurally analogous cationic and
formally zwitterionic PGM complexes supported by 3-PR2-2-
NR′2-indene and related monodeprotonated indenide ancillary
ligands, respectively (Chart 1).9-11 In the course of these
investigations, we became intrigued by the unusual modes of
substrate activation that might arise from net M∧X′ cooperat-
ivity involving a cationic PGM fragment and the 10π-electron
indenide unit within the ancillary ligand backbone of such
formally charge-separated zwitterions. While we have yet to
obtain definitive experimental evidence of net M∧X′ cooper-
ativity in our reactivity studies of these zwitterionic (κ2-P,N)-
PGM complexes, such behavior may underpin the remarkable
catalytic activity exhibited by a zwitterionic (κ2-P,N)Ru complex
in the transfer hydrogenation of ketones.9b
Building on these results and motivated by the remarkable
reactivity exhibited by [Cp*Ir(LX)]+ (Cp* ) η5-C5Me5)
intermediates in both stoichiometric12 and catalytic4b,13 substrate
transformations, we identified coordinatively unsaturated Cp*Ir
complexes supported by new chelating LX-type indene and
indenide ancillary ligands as worthwhile targets of inquiry.
Given that the reactivity properties of Ir-SR fragments within
mononuclear complexes are less well-documented than those
of Ir-OR and Ir-NR2 linkages3,4,14 and that isolable coordina-
tively unsaturated [Cp′Ir(κ2-P,S)]+X- complexes had not been
reported previously, we opted to develop synthetic routes to
new cationic and zwitterionic species featuring bidentate ligands
that pair neutral dialkylphosphino and anionic thiolate pendant
donor groups (Chart 1). Whereas cationic complexes of this type
featuring κ2-PR2,S-indene ligation may be well-suited to activate
substrates via M-X cooperativity, we envisioned that the
presence of a tethered anionic backbone within structurally
related zwitterionic complexes featuring κ2-PR2,S-indenide
ligation could provide access to alternative reaction manifolds
arising from less-conventional M∧X′ cooperative reactivity. We
(3) For selected reviews pertaining to the structural and reactivity
properties of PGM complexes featuring M-X fragments, see: (a)
Gunnoe, T. B. Eur. J. Inorg. Chem. 2007, 1185. (b) Fulton, J. R.;
Holland, A. W.; Fox, D. J.; Bergman, R. G. Acc. Chem. Res. 2002,
35, 44. (c) Holland, P. L.; Anderson, R. A.; Bergman, R. G. Comments
Inorg. Chem. 1999, 21, 115. (d) Bergman, R. G. Polyhedron 1995,
14, 3227. (e) Caulton, K. G. New J. Chem. 1994, 18, 25. (f) Fryzuk,
M. D.; Montgomery, C. D. Coord. Chem. ReV. 1989, 95, 1. (g)
Bryndza, H. E.; Tam, W. Chem. ReV. 1988, 88, 1163.
(4) For selected recent reviews pertaining to M-X cooperativity in PGM-
mediated catalysis, see: (a) Ito, M.; Ikariya, T. Chem. Commun. 2007,
5134. (b) Ikariya, T.; Blacker, A. J. Acc. Chem. Res. 2007, 40, 1300.
(c) Ikariya, T.; Murata, K.; Noyori, R. Org. Biomol. Chem. 2006, 4,
393. (d) Clapham, S. E.; Hadzovic, A.; Morris, R. H. Coord. Chem.
ReV. 2004, 248, 2201.
(5) Phillips, A. D.; Laurenczy, G.; Scopelliti, R.; Dyson, P. J. Organo-
metallics 2007, 26, 1120.
(6) A related cycloaddition process has been observed in cationic
(ꢀ-diketiminate)Al complexes: Radzewich, C. E.; Coles, M. P.; Jordan,
R. F. J. Am. Chem. Soc. 1998, 120, 9384.
(7) (a) Zhang, J.; Leitus, G.; Ben-David, Y.; Milstein, D. J. Am. Chem.
Soc. 2005, 127, 10840. (b) Gunanathan, C.; Ben-David, Y.; Milstein,
D. Science 2007, 317, 790.
(8) For related metal-ligand cooperativity in stoichiometric C-H and
H-H activation by Ir, see: Ben-Ari, E.; Leitus, G.; Shimon, L. J. W.;
Milstein, D. J. Am. Chem. Soc. 2006, 128, 15390.
(9) Complexes of donor-substituted indenide ligands can be described as
zwitterionic in that they lack conventional resonance structures that
would enable the indenide anionic charge to be delocalized onto the
pendant donor atoms. For (κ2-P,N)-PGM complexes, see: (a) Lundgren,
R. J.; Rankin, M. A.; McDonald, R.; Stradiotto, M. Organometallics
2008, 27, 254. (b) Lundgren, R. J.; Rankin, M. A.; McDonald, R.;
Schatte, G.; Stradiotto, M. Angew. Chem., Int. Ed. 2007, 46, 4732.
(c) Cipot, J.; McDonald, R.; Ferguson, M. J.; Schatte, G.; Stradiotto,
M. Organometallics 2007, 26, 594. (d) Rankin, M. A.; McDonald,
R.; Ferguson, M. J.; Stradiotto, M. Organometallics 2005, 24, 4981.
(10) For related examinations of PGM cations and borato-ligated zwitte-
rions, see: (a) Thomas, J. C.; Peters, J. C. J. Am. Chem. Soc. 2003,
125, 8870. (b) Betley, T. A.; Peters, J. C. Angew. Chem., Int. Ed.
2003, 42, 2385.
(11) For a relevant reactivity study involving Cp*Ir(TsDPEN) derivatives
(TsDPEN- ) H2NCHPhCHPhNTs-), see: Heiden, Z. M.; Rauchfuss,
T. B. J. Am. Chem. Soc. 2006, 128, 13048.
(12) For selected reports, see: (a) Klei, S. R.; Tilley, T. D.; Bergman, R. G.
Organometallics 2001, 20, 3220. (b) Klei, S. R.; Tilley, T. D.;
Bergman, R. G. J. Am. Chem. Soc. 2000, 122, 1816. (c) Arndtsen,
B. A.; Bergman, R. G.; Mobley, T. A.; Peterson, T. H. Acc. Chem.
Res. 1995, 28, 154. (d) Arndtsen, B. A.; Bergman, R. G. Science 1995,
270, 1970.
(13) Liu, J.; Wu, X.; Iggo, J. A.; Xiao, J. Coord. Chem. ReV. 2008, 252,
782.
(14) Klein, D. P.; Kloster, G. M.; Bergman, R. G. J. Am. Chem. Soc. 1990,
112, 2022.
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A R T I C L E S
Hesp et al.
cally equivalent isopropyl fragments within the PiPr2 group are
observed. Combustion analysis data obtained for [2]+X-
precludes the presence of an additional coligand, as does the
dark blue coloration of these complexes.17 To the best of our
knowledge, these represent the first examples of coordinatively
unsaturated [Cp′Ir(κ2-P,S)]+X- complexes. As anticipated for
such unsaturated species, exposure of a blue solution of
[2]+OTf- to an atmosphere of CO afforded cleanly an orange
solution of the C1-symmetric adduct [2·CO]+OTf- (νCO
)
2053 cm-1; for [Cp*Ir(CO)(TsDPEN)]+X- a value of 2064
cm-1 is observed11), from which the product was isolated as
an analytically pure, bright orange solid in 91% yield. Similarly,
treatment of [2]+B(C6F5)4- with PMe3 afforded the 18-electron
-
complex [2·PMe3]+B(C6F5)4 in 94% isolated yield. The
Figure 1. ORTEP diagrams for 1 (left) and [2·CO]+OTf- (right) shown
with 50% ellipsoids; selected H-atoms and the triflate counteranion in
[2·CO]+OTf- have been omitted for clarity.
connectivity in these [2·L]+X- adducts is supported by NMR
spectroscopic data, as well as X-ray diffraction data in the case
of [2 · CO]+OTf- (Figure 1). While efforts to prepare
[2·CH3CN]+X- by treatment of [2]+X- with excess CH3CN
resulted in the partial bleaching of the dark blue solution along
with the consumption of [2]+X- (31P NMR), an intractable
mixture of phosphorus-containing products was generated.
report herein on the strikingly divergent substrate activation
pathways (i.e., M-X versus M∧X′) that are traversed by such
coordinatively unsaturated cationic and zwitterionic Cp*Ir(κ2-
P,S) complexes in reactions with acetonitrile and other L-donor
ligands, as well as with organosilanes. We also report on our
synthetic and reactivity investigations of related Rh complexes,
including the application of cationic Cp*Rh(κ2-P,S) species in
the catalytic hydrosilylation of ketones.
Pursuit of the Coordinatively Unsaturated Zwitterion 3.
Having successfully prepared the new coordinatively unsaturated
cationic Ir complexes [2]+X-, we turned our focus to the
synthesis of the structurally related zwitterion 3 (Scheme 2).
Efforts to prepare 3 via HX extrusion from 1 or [2]+X-
employing NaN(SiMe3)2 afforded a green solid that exhibits
Results and Discussion
The precursory compound Cp*Ir(Cl)(κ2-3-PiPr2-2-S-indene)
1 was prepared in 95% isolated yield from an isomeric mixture
of 1/3-PiPr2-2-StBu-indene and 0.5 equiv of [Cp*IrCl2]2 (eq 1).
The structure of 1 was determined initially on the basis of NMR
spectroscopic data, and subsequently was confirmed by use of
single-crystal X-ray diffraction techniques. An ORTEP15 dia-
gram of 1 is provided in Figure 1, while X-ray experimental
data and selected metrical parameters for each of the crystal-
lographically characterized complexes reported herein are col-
lected in Tables 1 and 2, respectively. The structural features
in 1 are not unusual and can be compared with those found in
a related Cp*Ir(κ2-P,S)Cl complex.16
1
broad H and 31P NMR features (223-333 K; δ 31P ca. 44)
and which has thus far resisted crystallization. Alternatively,
treatment of 1 with K2CO3 in CH3CN led to the consumption
of 1 along with the formation of one major product (3·CH3CN,
>90% on the basis of 31P NMR data). Upon workup, 3·CH3CN
was obtained as analytically pure, brown crystals in 41% isolated
yield. Combustion analysis, NMR, and X-ray diffraction data
(Figure 2) all support the identification of this product as the
unusual tripodal κ3-P,S,N Ir-iminato species 3·CH3CN, in
which the CH3CN can be described as bridging the Lewis acidic
Cp*Ir and Lewis basic indenide fragments of zwitterionic 3 (i.e.,
net M∧X′ cooperative reactivity). In keeping with such a
formulation, the normally linear acetonitrile moiety adopts a
bent structure (N-C27-C28 ) 121.6(2)°) in 3·CH3CN, with
the sum of the angles at C27 (359.9°) being consistent with a
trigonal planar geometry. Such crystallographically characterized
Ir-iminato complexes are rare,18 and there is scant precedent
for net metal-ligand cooperative activation of nitriles involving
a mononuclear Cp*Ir complex.19 While the aforementioned
green solid that is formed upon treatment of 1 or [2]+X- with
(17) Among the few coordinatively unsaturated Cp*IrIII complexes that
have been isolated, most are violet-blue in coloration: (a) Ringenberg,
M. R.; Kokatam, S. L.; Heiden, Z. M.; Rauchfuss, T. B. J. Am. Chem.
Soc. 2008, 130, 788. (b) Arita, S.; Koike, T.; Kayaki, Y.; Ikariya, T.
Organometallics 2008, 27, 2795. (c) Mashima, K.; Abe, T.; Tani, K.
Chem. Lett. 1998, 1201. (d) Grotjahn, D. B.; Groy, T. L. J. Am. Chem.
Soc. 1994, 116, 6969.
Synthesis and L-Donor Reactivity of the Coordinatively
Unsaturated Cations [2]+X-. Treatment of an orange solution
of 1 in CH2Cl2 with AgOTf or LiB(C6F5)4 ·2.5OEt2 in each case
resulted in the quantitative conversion to a single phosphorus-
containing product (31P NMR) accompanied by an immediate
color change to dark blue (Scheme 1). Our assignment of these
products as the targeted coordinatively unsaturated, Cs-sym-
metric [2]+X- complexes (X ) OTf, 78%; X ) B(C6F5)4, 82%)
(18) A nitrile activation process involving metalation of (η5-C5Me5)Ir and
leading to a crystallographically characterized Ir-iminato complex has
been reported: Tellers, D. M.; Ritter, J. C. M.; Bergman, R. G. Inorg.
Chem. 1999, 38, 4810.
1
is entirely consistent with H and 13C NMR spectra obtained
(19) For alternative modes of stoichiometric nitrile activation within the
coordination sphere of Cp*M complexes (M ) Rh, Ir), see: (a) Wang,
X.; Chen, H.; Li, X. Organometallics 2007, 26, 4684. (b) Taw, F. L.;
Mueller, A. H.; Bergman, R. G.; Brookhart, M. J. Am. Chem. Soc.
2003, 125, 9808. (c) Taw, F. L.; White, P. S.; Bergman, R. G.;
Brookhart, M. J. Am. Chem. Soc. 2002, 124, 4192. (d) Chin, C. S.;
Chong, D.; Lee, B.; Jeong, H.; Won, G.; Do, Y.; Park, Y. J.
Organometallics 2000, 19, 638.
for these species, in which resonances attributable to magneti-
(15) ORTEP-3 for Windows version 1.074: Farrugia, L. J. J. Appl.
Crystallogr. 1997, 30, 565.
(16) Gorol, M.; Roesky, H. W.; Noltemeyer, M.; Schmidt, H.-G. Eur.
J. Inorg. Chem. 2005, 4840.
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Cp*M(κ2-P,S) Complexes
A R T I C L E S
Table 1. Crystallographic Data for 1, [2·CO]+OTf-, 3·CH3CN, 7, and 11
1
[2·CO]+OTf-
3·CH3CN
7
11
empirical formula
formula weight
crystal dimensions
crystal system
space group
a (Å)
C25H35ClIrPS
626.21
0.64 × 0.57 × 0.33
monoclinic
P21/c
8.4287(9)
18.747(2)
15.3597(17)
90
91.1555(15)
90
2426.5(5)
4
1.714
5.774
0.2516-0.1194
54.90
C27H35F3IrO4PS2
767.84
C27H37NIrPS
630.81
0.40 × 0.40 × 0.23
monoclinic
P21/c
8.0173(5)
19.3970(13)
16.3635(11)
90
95.6603(9)
90
2532.3(3)
4
1.655
5.433
0.3680-0.2199
54.98
C51H41BF20IrPS
1299.88
0.33 × 0.23 × 0.11
monoclinic
P21
11.2171(9)
12.4867(10)
18.0424(14)
90
103.9330(10)
90
2452.7(3)
2
1.760
2.910
0.7402-0.4468
54.98
C37H46IrPSSi
774.06
0.34 × 0.22 × 0.07
0.24 × 0.20 × 0.18
orthorhombic
Pna21
16.2760(12)
9.3991(7)
22.3078(16)
90
90
90
3412.6(4)
4
1.507
4.080
0.5271-0.4410
54.96
-21 e h e 21
-12 e k e 12
-28 e l e 28
28450
7816
0.0331
triclinic
j
P1
9.1759(8)
10.9655(8)
15.4658(9)
80.643(2)
75.359(2)
80.987(2)
1474.66(19)
2
1.729
4.773
0.7165-0.2878
55.06
-11 e h e 11
-13 e k e 14
-0 e l e 20
12226
12226
na
b (Å)
c (Å)
R (deg)
ꢀ (deg)
γ (deg)
V (Å3)
Z
Fcalcd (g cm-3
)
µ (mm-1
)
range of transmission
2θ limit (deg)
index ranges
-10 e h e 10
-24 e k e 24
-19 e l e 19
21057
5539
0.0261
-10 e h e 10
-25 e k e 25
-21 e l e 21
21919
5811
0.0188
-14 e h e 14
-16 e k e 16
-23 e l e 23
20942
11110
0.0221
total data collected
ind reflections
Rint
obd reflections
data/restraints/params
goodness-of-fit
5311
5539/0/267
1.169
0.0245
0.0617
11389
12226/0/349
1.027
0.0378
0.0945
5416
5811/0/286
1.097
0.0203
0.0512
10394
11110/1/685
0.921
0.0244
0.0548
7138
7816/1/379
1.028
0.0274
0.0657
2
R1 [Fo g 2σ(Fo2)]
2
wR2 [Fo g -3σ(Fo2)]
Table 2. Selected Interatomic Distances (Å) and Angles (deg) for
1, [2·CO]+OTf-, 3·CH3CN, 7, and 11
Scheme 2
1a
[2·CO]+OTf-b 3·CH3CNc
7d
11e
Ir-P
2.3220(8)
2.3566(9)
1.718(3)
2.350(1)
2.378(1)
1.734(5)
1.792(4)
1.519(6)
1.351(6)
2.2725(6) 2.2787(9) 2.267(1)
2.3787(6) 2.2912(8) 2.345(1)
1.730(3) 1.759(4) 1.729(4)
1.875(3) 1.817(4) 1.797(4)
1.531(3) 1.496(5) 1.503(6)
1.359(4) 1.350(5) 1.367(5)
Ir-S
S-Cind
iPr2P-Cind 1.797(3)
C1-C2
C2-C3
1.516(4)
1.358(4)
a Ir-Cl 2.4021(9). b Ir–CO 1.887(5); IrC-O 1.119(5). c Ir-N
2.053(2); N-C27 1.270(3); C1-C27 1.543(4); C27-C28 1.509(4);
N-C27-C28 121.6(2); N-C27-C1 120.1(2); C1-C27-C28 118.2(2).
d S-CH2CH3 1.836(4). e Si-Cind 1.900(4).
ligand in 3 · CH3CN (1H NMR). In viewing 3 · CH3CN as a
potentially reactive source of the zwitterion 3, we sought to
explore further the L-donor substrate activation chemistry of
3·CH3CN to allow for comparisons to be made with the related
Scheme 1
NaN(SiMe3)2 behaves as a source of 3 in generating 3·CH3CN
or 11 (Vide infra) as the major product (31P NMR) upon addition
of CH3CN or Ph2SiH2 (respectively), we are presently unable
to unequivocally confirm the identity (or purity) of this green
solid as being the desired zwitterionic species 3.
Probing the Reactivity of 3 ·CH3CN with CO and PMe3. The
rapid formation of 3·CD3CN and 1 equiv of free CH3CN upon
addition of CD3CN (5 equiv, 15 min) to a solution of 3·CH3CN
in C6D6 confirmed the lability of the coordinated acetonitrile
Figure 2. ORTEP diagram for 3 · CH3CN shown with 50% ellipsoids;
selected H-atoms have been omitted for clarity.
9
J. AM. CHEM. SOC. VOL. 130, NO. 48, 2008 16397

A R T I C L E S
Hesp et al.
Scheme 3
cations [2]+X-. Unexpected reactivity was observed between
3·CH3CN and CO (Scheme 3). Unlike the clean formation of
[2·CO]+OTf- that occurred upon treatment of [2]+OTf- with
CO (Vide supra), exposure of 3·CH3CN to an atmosphere of
CO did not afford the anticipated adduct 3·CO; rather, NMR
analysis of the reaction mixture revealed the clean formation
of (κ2-3-PiPr2-2-S-indene)Ir(CO)2 4 and 1,2,3,4-tetramethylful-
vene (1:1).20 To confirm this structural assignment, compound
4 was prepared independently from (κ2-3-PiPr2-2-S-indene)Ir-
(COD) and CO. The formation of 4 in the reaction of 3·CH3CN
with CO can be viewed as arising from net deprotonation of
(η5-C5Me5)Ir21 by the indenide unit in 3 (or possibly 3·CO),
followed by substitution of the coordinated 1,2,3,4-tetrameth-
ylfulvene by CO ligands. In contrast to the quantitative
conversion of 3·CH3CN into 4, treatment of 1 or [2·CO]+OTf-
with NaN(SiMe3)2 followed by the introduction of an atmo-
sphere of CO gave rise to a mixture of phosphorus-containing
products in which 4 represented less than 50% of the reaction
Figure 3. ORTEP diagram for 7 shown with 50% ellipsoids; selected
H-atoms and the borate counteranion have been omitted for clarity.
Scheme 4
mixture (on the basis of 31P NMR data). Whereas addition of
-
PMe3 to [2]+B(C6F5)4
afforded the isolable adduct
[2·PMe3]+B(C6F5)4 (Vide supra), under similar conditions,
3·CH3CN gave rise to a first-formed bis(phosphine)Ir product22a
(ca. 75%, possibly corresponding to 3·PMe3) that was observed
to decompose to a mixture of phosphorus-containing products
upon standing in solution or upon workup. Notably, treatment
-
Scheme 5
-
of [2·PMe3]+B(C6F5)4 with NaN(SiMe3)2 affords an as-yet-
unidentified bis(phosphine)Ir product (31P NMR)22b that differs
from the first-formed product generated upon addition of PMe3
to 3·CH3CN and which we have yet to isolate in pure form.
Net M-X Cooperative H-Si Bond Activation by [2]+B-
(C6F5)4-. Intrigued by the differing L-donor substrate activation
pathways exhibited by [2]+X- and 3, we turned our attention
to the study of H-E bond activation chemistry mediated by
these structurally related complexes. The activation of H-Si
containing substrates was selected as an entry point for these
investigations, given the propensity of coordinatively unsaturated
Cp*Ir complexes to mediate unusual transformations of
organosilanes.12a,b Treatment of [2]+OTf- with Ph2SiH2 resulted
in the net loss of Ph2Si(OTf)H to give 5 in 44% isolated yield
(Scheme 4). In contrast, the analogous reaction involving
[2]+B(C6F5)4- proceeded via H-Si addition across Ir-S (i.e.,
net M-X cooperative reactivity) to give the cationic hydrido
species 6a (68% isolated yield), which features a newly
established S-SiHPh2 linkage. Although, under similar condi-
tions employing PhSiH3, the related addition product 6b was
obtained in 77% isolated yield, an intractable mixture of
products was generated upon addition of Ph3SiH to
[2]+B(C6F5)4-. While to the best of our knowledge net H-Si
addition across an M-SR linkage to give an isolable mono-
nuclear addition product has not been reported previously in
the literature, the related activation of H2 by dinuclear complexes
featuring an M2S2 core (e.g., M ) Rh,23 Ir24) is known. No
reaction was observed (1H and 31P NMR) upon exposure of
[2]+X- to H2 (ca. 1 atm) at ambient temperature over the course
of five days. Interestingly, while [2]+X- proved unreactive
toward diethyl ether, the H-Si addition product 6a effected net
C-O bond cleavage in this substrate with net loss of
Ph2Si(OEt)H over the course of 24 h at ambient temperature
(in the absence of spectroscopically observable intermediates),
thereby affording the cationic Ir-S-Et complex 7 in 77%
isolated yield (Scheme 5). An ORTEP15 diagram for 7 is
presented in Figure 3. The structural features of 7 can be
compared with those of Cp*(H)Ir(PMe3)(StBu), the only closely
(20) The 1,2,3,4-tetramethylfulvene byproduct was identified by comparison
to published spectral data: Hashimoto, H.; Tobita, H.; Ogino, H.
Organometallics 1993, 12, 2182.
(23) Ienco, A.; Calhorda, M. J.; Reinhold, J.; Reineri, F.; Bianchini, C.;
Peruzzini, M.; Vizza, F.; Mealli, C. J. Am. Chem. Soc. 2004, 126,
11954, and references cited therein.
(24) Linck, R. C.; Pafford, R. J.; Rauchfuss, T. B. J. Am. Chem. Soc. 2001,
123, 8856, and references cited therein.
(21) Glueck, D. S.; Bergman, R. G. Organometallics 1990, 9, 2862.
(22) (a)31P{1H} NMR (CDCl3): δ 25.0 (d, 2JPP ) 27.9 Hz),-37.7 (d, 2JPP
) 27.9 Hz). (b)31P{1H} NMR (CH2Cl2): δ 34.1 (d, 2JPP ) 28.8 Hz),-
2
40.8 (d, JPP ) 28.0 Hz).
9
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Cp*M(κ2-P,S) Complexes
A R T I C L E S
Scheme 6
4) is also transformed cleanly into PhMeC(H)(OSiPh2H) and
[2]+OTf- upon treatment with acetophenone (1H and 31P
NMR). On the basis of these observations, and in the absence
of further mechanistic data, we are presently unable to comment
definitively regarding the role of the sulfur atom participation
in acetophenone hydrosilylation reactions involving 6a and/or
mixtures of Ph2Si(OTf)H and 5.
Formation of Rh Complexes and Ketone Hydrosilylation
Catalysis. Having established that Ph2SiH2 adds cleanly to the
-
Ir-S linkage in [2]+B(C6F5)4 and that the resulting adduct
6a can transfer the activated silane to acetophenone, the ability
-
of [2]+B(C6F5)4 to catalyze the hydrosilylation of acetophe-
none with Ph2SiH2 was examined. However, only modest
conversions (<20%, on the basis of GC-FID data) were achieved
under a variety of conditions employing 2.0 mol% [2]+B-
related Cp*Ir complex for which crystallographic data have been
reported.14 We are presently unable to comment definitively
regarding the mechanistic details of the conversion of 6a into
7; while such reactivity may arise from SN2 attack of diethyl
ether on silicon in 6a, alternative reaction pathways involving
silylium ion that could be transiently generated upon loss of
[Ph2SiH]+BAr4- from 6a cannot be discounted.25 Notably, the
mixture of Ph2Si(OTf)H and 5 that is apparently formed upon
treatment of [2]+OTf- with Ph2SiH2 (Scheme 4) was not
observed to react with diethyl ether under similar conditions
(1H and 31P NMR).
-
(C6F5)4 (prepared in situ from 2.0 mol% 1 and 2.0 mol%
LiB(C6F5)4 ·2.5Et2O). In the pursuit of an analogous system that
might offer improved catalytic activity, we turned our attention
to the preparation of Cp*Rh derivatives of 1/3-PiPr2-2-StBu-
indene (Scheme 7). Treatment of 1/3-PiPr2-2-StBu-indene with
0.5 equiv of [Cp*RhCl2]2 afforded Cp*Rh(Cl)(κ2-3-PiPr2-2-S-
indene) (8) as an analytically pure, light brown solid in 94%
isolated yield. In keeping with the stoichiometric reactions
observed in the Ir system, combination of 8 and LiB(C6F5)4 ·
2.5Et2O resulted in the consumption of 8 along with the
formation of a dark green solution of the desired coordinatively
Stoichiometric Silane Transfer from 6a to Acetophenone.
Toste and co-workers26 have reported that (PPh3)2Re(O)2I
catalyzes the hydrosilylation of carbonyl compounds by way
of a previously unprecedented mechanism involving net H-Si
addition across a RedO linkage. Given the conceptual relation-
ship between this elementary reaction step and the stoichiometric
unsaturated cation [9]+B(C6F5)4- (ca. 75% on the basis of 31
P
NMR data), which in turn was transformed into an orange
solution of 10 (ca. 80% on the basis of 31P NMR data) upon
addition of Ph2SiH2 to the reaction mixture. However, we have
-
H-Si addition of Ph2SiH2 to [2]+B(C6F5)4 giving 6a, and in
-
thus far not been able to isolate [9]+B(C6F5)4 or 10 in
light of the apparent ability of 6a to effect the silylation of
diethyl ether (Vide supra), we sought to assess the ability of 6a
to transfer the bound fragments of the activated silane to
unsaturated substrates. While no reaction was observed visually
or by use of NMR methods upon exposure of 6a to excess
styrene (10 equiv; Scheme 5), treatment of an initially orange
solution of 6a (ca. 0.05 mmol) in CH2Cl2 (2 mL) with excess
acetophenone (0.26 mmol) resulted in a color change of the
solution to dark blue over the course of several minutes at
ambient temperature, in keeping with the formation of
analytically pure form, and efforts to explore the ability of 10
to transfer silane to acetophenone in a stoichiometric fashion
(as was observed for the Ir analogue 6a; Scheme 6) have been
thwarted by the apparent instability of 10. Furthermore, attempts
to prepare Rh analogues of 3 or 3·CH3CN by using similar
protocols resulted in complex reaction mixtures from which no
pure materials could be isolated.
In a preliminary catalytic survey of the ambient temperature
hydrosilylation of acetophenone employing 2.0 mol% [9]+B-
-
-
[2]+B(C6F5)4 (Scheme 6). This qualitative assessment was
(C6F5)4 (prepared in situ from a mixture of 2.0 mol% 8 and
2.0 mol% LiB(C6F5)4 ·2.5Et2O), efficient conversion (1H NMR)
to the corresponding silyl ether was achieved by using either
Ph2SiH2 (85%) or PhSiH3 (98%); by comparison, negligible
conversion (<5%) was noted for analogous reactions employing
Ph3SiH. The inability of [9]+B(C6F5)4- to catalyze the reduction
of acetophenone employing Ph3SiH may correlate with the
complex stoichiometric reactivity observed between the Ir
substantiated on the basis of 31P NMR data obtained after a
total reaction time of 0.25 h, which confirmed the consumption
of 6a with concomitant formation of [2]+B(C6F5)4- as the major
product (>85% on the basis of 31P NMR). Subsequent addition
of Ph2SiH2 to this reaction mixture led to the complete
-
transformation of [2]+B(C6F5)4 back into 6a (31P NMR). In
an effort to monitor the fate of the H-Si fragment in these
-
analogue [2]+B(C6F5)4 and this tertiary silane (Vide supra).
-
reactions, [2]+B(C6F5)4 was treated with Ph2SiD2, affording
Consistent with the stoichiometric reactivity observed for 6a-
d2 (Vide supra), the catalytic reduction of acetophenone mediated
by [9]+B(C6F5)4- and employing Ph2SiD2 produced exclusively
PhMeC(D)(OSiPh2D). Encouraged by these preliminary results,
6a-d2, in which deuterium incorporation was observed only at
the Si-H and Ir-H positions. In keeping with a process involving
net transfer of Ir-D and S-SiDPh2 fragments, the addition of
acetophenone to 6a-d2 produced exclusively PhMeC(D)-
(OSiPh2D) on the basis of NMR data. While these experiments
unequivocally confirm the ability of 6a to transfer Ph2SiH2 to
acetophenone in a stoichiometric fashion, we have also observed
that an in situ generated mixture of Ph2Si(OTf)H and 5 (Scheme
-
the ability of in situ prepared [9]+B(C6F5)4 to catalyze the
hydrosilylation of various ketone substrates using PhSiH3 was
examined (THF, 5 h, ambient temperature; Table 3); for
convenience, the progress of each hydrosilylation reaction was
monitored through analysis of the product mixture obtained
following hydrolytic workup (eq 2). In keeping with the
preliminary catalytic survey, the reduction of acetophenone
proceeded with near quantitative conversion (98%, entry 1) on
the basis of GC-FID data, thereby enabling the isolation of
PhMeC(H)(OH) in 89% yield. Furthermore, in situ prepared
(25) Parks, D. J.; Blackwell, J. M.; Piers, W. E. J. Org. Chem. 2000, 65,
3090, and references cited therein.
(26) (a) Nolin, K. A.; Krumper, J. R.; Pluth, M. D.; Bergman, R. G.; Toste,
F. D. J. Am. Chem. Soc. 2007, 129, 14684. (b) Kennedy-Smith, J. J.;
Nolin, K. A.; Gunterman, H. P.; Toste, F. D. J. Am. Chem. Soc. 2003,
125, 4056.
9
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A R T I C L E S
Hesp et al.
Scheme 7
-
[9]+B(C6F5)4 proved effective in reducing a range of other
aryl alkyl ketones (entries 2-5), functionalized acetophenones
(entries 6-8), and diaryl ketones (entries 9 and 10).
pathways that would lead to scrambling of the isotopic label
(e.g., C-H/Si-D exchange). Upon treatment of the cationic
H-Si addition product 6a with NaN(SiMe3)2, 11a,b is generated
as the major phosphorus-containing species (ca. 75%, 31P NMR).
This result supports the possible intermediacy of 6a′ (the
conjugate base of 6a; Scheme 8) as an unobserved first-formed
addition product in the reaction of Ph2SiH2 with putative 3,
which in turn could rearrange to 11a,b via net transfer of
Ph2HSi+ from sulfur to the indenide backbone. On the basis of
these and other observations, we are currently conducting
mechanistic experiments directed toward ascertaining if the
H-Si bond cleavage process leading to 11a,b involves the net
addition of silane across a single molecule of 3. Unlike the case
of 6a, no reaction was observed between 11a,b and acetophe-
none, suggesting that the newly formed Si-Cindenide linkage in
such complexes must be rendered more labile (via ancillary
ligand modification) in order to allow for the incorporation of
such net M∧X′ cooperative H-Si activation steps into produc-
tive catalytic cycles.
Net M∧X′ Cooperative H-Si Bond Activation Employing
3·CH3CN. Having documented the addition of H-Si fragments
to M-S linkages in [2]+B(C6F5)4 and [9]+B(C6F5)4-, we
-
sought to explore if the indenide fragment in the structurally
related Ir zwitterion 3 might provide access to alternative net
M∧X′ cooperative reaction pathways in σ-bond activation
chemistry. Whereas no reaction was observed upon exposure
of [2]+X- to H2 (ca. 1 atm) at ambient temperature, reactions
conducted under similar conditions employing 3·CH3CN (as a
source of 3) produced a complex mixture of phosphorus-
containing products (31P NMR). Conversely, treatment of
3·CH3CN with Ph2SiH2 resulted in the liberation of CH3CN
(1H NMR) along with the quantitative formation of 11 (64%
isolated yield; Scheme 8). Notably, the formation of 11
corresponds to heterolytic H-Si bond activation, involving net
addition of H- and Ph2HSi+ fragments to Ir and indenide
(respectively) in the unobserved zwitterion 3. Compound 11 is
formed as a mixture of two diastereomers (11a,b, ca. 3:1) that
arise from the stereogenic nature of C1 and Ir, and a similar
11a,b mixture can be prepared via addition of NaN(SiMe3)2 to
a solution of 1 and Ph2SiH2 (79% isolated yield). Both
diastereomers of 11 are detected early on in each synthesis in
the absence of other phosphorus-containing products (31P NMR),
and their relative proportions in the final reaction mixture do
not change substantially, even upon heating. While the con-
nectivity in 11a,b was determined initially on the basis of NMR
data, single crystals obtained from the reaction mixture that were
subjected to X-ray diffraction analysis correspond to the
diastereomer of 11 whereby the Ir-H and C1-SiHPh2 groups
adopt an anti-relationship with regard to the plane defined by
the indene backbone of 11 (Figure 4). Reactions employing
Ph2SiD2 afforded 11-d2, in which exclusive deuterium incor-
poration at the Si-H and Ir-H positions of both diastereomers
was noted, thereby precluding more complex mechanistic
Summary and Conclusions
In summary, we have described our efforts to prepare and
characterize a previously unreported class of coordinatively
unsaturated cationic ([2]+X-) and formally zwitterionic (3)
Cp*Ir(κ2-P,S) complexes that feature structurally analogous
monoanionic κ2-PiPr2,S-indene and dianionic κ2-PiPr2,S-indenide
ancillary ligands, respectively. The versatility of donor-func-
tionalized indene ancillary ligands in allowing for the selection
of divergent metal-ligand cooperativity pathways (simply by
ancillary ligand deprotonation) in the activation of small
molecule substrates was demonstrated in comparative reactivity
studies involving [2]+X- and putative 3. In this regard, the
-
cationic complex [2]+B(C6F5)4 was observed to activate
organosilanes via the first well-documented H-Si addition
across an M-SR linkage (i.e., net M-X cooperative reactivity);
the resulting adduct proved capable of effecting the stoichio-
metric silylation of diethyl ether via C-O bond cleavage and
9
16400 J. AM. CHEM. SOC. VOL. 130, NO. 48, 2008

Cp*M(κ2-P,S) Complexes
A R T I C L E S
Table 3. Rh-Catalyzed Hydrosilylation of Ketonesa
Figure 4. ORTEP diagram for one diastereomer of 11 shown with 50%
ellipsoids; selected H-atoms have been omitted for clarity.
Scheme 8
a Reaction conditions: 0.2 mmol of ketone, 0.3 mmol of PhSiH3, 2.0
mol % 8, and 2.0 mol % LiB(C6F5)4 ·2.5Et2O in 2 mL of THF at
ambient temperature for 5 h. b Conversion to the secondary alcohol
determined on the basis of GC-FID data. c Isolated yield of 89% (>95%
purity on the basis of 1H NMR data) when the reaction was conducted
on a 0.8 mmol ketone scale.
zwitterion (i.e., net M∧X′ cooperative reactivity). Building on
these and other encouraging observations, we are currently
examining in greater detail the utility of donor-functionalized
indene and indenide ancillary ligands in the development of
selective new stoichiometric and catalytic substrate activation
chemistry that is enabled by novel metal-ligand cooperative
behavior.
Experimental Section
of selectively transferring the bound fragments of the activated
silane to acetophenone. Related cationic Cp*Rh complexes
exhibited similar stoichiometric H-Si bond activation chemistry
and in turn proved capable of mediating the catalytic hydrosi-
lylation of various ketone substrates. The possible involvement
of H-Si addition to M-SR as an elementary step in this
catalysis is intriguing, in that such a transformation is without
precedent in metal-mediated hydrosilylation chemistry. Con-
versely, the unusual stoichiometric reactivity of putative 3 with
CH3CN or Ph2SiH2 can be viewed as resulting from the dual
action of the Lewis acidic Cp*Ir fragment and the Lewis basic
10π-electron indenide unit within this formally charge-separated
General Considerations. All manipulations were conducted in
the absence of oxygen and water under an atmosphere 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 for 5 days and then evacuated for 24 h prior to use. The
nondeuterated solvents dichloromethane, diethyl ether, tetrahydro-
furan, benzene, toluene, and pentane were deoxygenated and dried
by sparging with dinitrogen gas, followed by passage through a
double-column solvent purification system purchased from mBraun
Inc. Dichloromethane, tetrahydrofuran, and diethyl ether were
purified over two alumina-packed columns, while benzene, toluene,
9
J. AM. CHEM. SOC. VOL. 130, NO. 48, 2008 16401

A R T I C L E S
Hesp et al.
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. CDCl3 (Aldrich) was degassed by using
three repeated freeze-pump-thaw cycles, dried over CaH2 for 7
days, distilled in Vacuo, and stored over 4 Å molecular sieves for
24 h prior to use. Benzene-d6, tetrahydrofuran-d8, and methylene
chloride-d2 (Cambridge Isotopes) were degassed by using three
repeated freeze-pump-thaw cycles and then dried over 4 Å
molecular sieves for 24 h prior to use. All solvents used within the
glovebox were stored over activated 4 Å molecular sieves. The
ligand precursor 1/3-PiPr2-2-StBu-indene was prepared by using
literature procedures27 and was dried in Vacuo for 24 h prior to
use. NaN(SiMe3)2 (Aldrich), anhydrous K2CO3 (Aldrich), [(COD)-
IrCl]2 (Strem), [Cp*IrCl2]2 (Strem), [Cp*RhCl2]2 (Strem), and
LiB(C6F5)4 ·2.5Et2O (Boulder Scientific) were dried in Vacuo for
24 h prior to use (COD ) η4-1,5-cyclooctadiene; Cp* ) η5-C5Me5).
Ph3SiH, Ph2SiH2, and PhSiH3 (Gelest, shipped under argon) were
dried over 4 Å molecular sieves for 24 h prior to use; Ph2SiD2 was
prepared via reduction of Ph2SiCl2 with LiAlD4 and was dried over
4 Å molecular sieves for 24 h prior to use. All ketones were
obtained from commercial sources in high purity; solid ketones were
dried in Vacuo for a minimum of 12 h prior to use, while liquid
ketones were degassed by use of three repeated freeze-pump-thaw
cycles. All other reagents were used as received. 1H, 13C, 29Si,
and 31P NMR characterization data were collected at 300 K on a
Bruker AV-500 spectrometer operating at 500.1, 125.8, 99.4, and
202.5 MHz (respectively) with chemical shifts reported in parts
per million downfield of SiMe4 (for 1H, 13C, and 29Si) or 85%
H3PO4 in D2O (for 31P). 1H and 13C NMR chemical shift
assignments are made on the basis of data obtained from 13C-DEPT,
1H-1H COSY, 1H-13C HSQC, and 1H-13C HMBC NMR
59.7 (CH (COD)), 42.2 (d, 3JPC ) 13.1 Hz, C1), 33.8 (CH2 (COD)),
29.5 (CH2 (COD)), 25.8 (d, 1JPC ) 28.8 Hz, P(CHMeaMeb)), 19.6
(P(CHMeaMeb)), 18.3 (d, 2JPC ) 3.0 Hz, P(CHMeaMeb)). 31P{1H}
NMR (CDCl3): δ 45.9.
Synthesis of 1. To a magnetically stirred mixture of [Cp*IrCl2]2
(0.25 g, 0.32 mmol) and CH2Cl2 (5 mL) was added a solution of
1/3-PiPr2-2-StBu-indene (0.20 g, 0.64 mmol) in CH2Cl2 (1 mL).
After 20 h of magnetic stirring at ambient temperature, 31P NMR
analysis of the reaction mixture confirmed the consumption of the
starting material and the presence of a single new phosphorus-
containing product (1). The solvent and other volatiles were
removed in Vacuo, affording an orange solid that was washed with
pentane (2 × 2 mL). Removal of the solvent from the residual solid
afforded 1 as an analytically pure, orange solid (0.38 g, 0.62 mmol,
97%). Anal. Calcd for C25H35ClIrPS: C, 47.95; H, 5.63; N, 0.00.
1
Found: C, 47.91; H, 5.49; N, <0.3. H NMR (CDCl3): δ 7.18 (d,
3JHH ) 7.5 Hz, 1H, C4 or C7), 7.14 (d, 3JHH ) 7.0 Hz, 1H, C4 or
3
3
C7), 7.12 (t, JHH ) 7.0 Hz, 1H, C5 or C6), 6.97 (d of t, JHH
)
7.0 Hz, J ) 1.0 Hz, C5 or C6), 3.67-3.51 (m, 2H, C1(H)2), 3.46
(m, 1H, P(CHMeaMeb)), 2.18 (m, 1H, P(CHMecMed)), 1.82 (d, J
) 2.0 Hz, 15H, C5Me5), 1.51 (d of d, 3JPH ) 15.0 Hz, 3JHH ) 7.0
Hz, 3H, P(CHMeaMeb)), 1.38 (d of d, 3JPH ) 12.5 Hz, 3JHH ) 7.0
Hz, 3H, P(CHMecMed)), 1.36 (d of d, 3JPH ) 11.5 Hz, 3JHH ) 7.0
Hz, 3H, P(CHMeaMeb)), 1.00 (d of d, 3JPH ) 16.0 Hz, 3JHH ) 7.0
Hz, 3H, P(CHMecMed)). 13C{1H} NMR (CDCl3): δ 179.4 (d, 2JPC
) 22.8 Hz, C2), 148.6 (d, JPC ) 7.5 Hz, C3a or C7a), 145.1 (d,
1
JPC ) 4.2 Hz, C7a or C3a), 128.0 (d, JPC ) 60.1 Hz, C3), 126.2
(C5 or C6), 124.2 (C6 or C5), 121.7 (C4 or C7), 117.6 (C7 or C4),
92.5 (d, 2JPC ) 2.8 Hz, C5Me5), 41.9 (d, 3JPC ) 10.6 Hz, C1), 30.7
1
1
(d, JPC ) 28.8 Hz, P(CHMecMed)), 25.6 (d, JPC ) 35.6 Hz,
2
P(CHMeaMeb)), 20.3 (d, JPC ) 1.4 Hz, P(CHMeaMeb)), 20.1 (d,
2JPC ) 6.4 Hz, P(CHMecMed)), 19.8 (d, JPC ) 5.7 Hz, P(CH-
2
-
experiments, and 13C resonances associated with B(C6F5)4 and
2
MeaMeb)), 18.1 (d, JPC ) 1.6 Hz, P(CHMecMed)), 9.1 (C5Me5).
-
SO3CF3 (OTf-) were not assigned. 29Si NMR chemical shift
31P{1H} NMR (CDCl3): δ 32.9. Crystals suitable for X-ray
crystallographic analysis were grown by vapor diffusion of pentane
into a concentrated solution of 1 in benzene at ambient temperature.
Synthesis of [2]+OTf-. To a magnetically stirred solution of 1
(0.029 g, 0.047 mmol) in CH2Cl2 (2 mL) was added solid AgOTf
(0.012 g, 0.047 mmol), which effected an immediate color change
from orange to dark blue, accompanied by the formation of
precipitate. The blue solution was magnetically stirred for 0.5 h;
31P NMR analysis of the reaction mixture showed complete
consumption of 1 and the presence of a single new phosphorus-
containing product ([2]+OTf-). The precipitate was then removed
by filtration through Celite. Removal of the solvent and other
volatiles afforded a dark blue solid that was triturated with pentane
(2 × 2 mL) followed by removal of the pentane layer by use of a
Pasteur pipet. Residual pentane and other volatiles were removed
in Vacuo, affording [2]+OTf- as an analytically pure, dark blue
solid (0.028 g, 0.037 mmol, 78%). Anal. Calcd for C26H35F3IrO3PS2:
C, 42.20; H, 4.77; N, 0.00. Found: C, 42.12; H, 4.69; N, <0.3. 1H
NMR (CD2Cl2): δ 7.44 (d, 3JHH ) 7.5 Hz, 1H, C4-H or C7-H),
7.39 (d, 3JHH ) 7.5 Hz, 1H, C4-H or C7-H), 7.33 (t, 3JHH ) 7.5
assignments are given on the basis of data obtained from 1H-29Si
HMQC NMR experiments. UV-vis data were obtained using a
Varian Cary 100 Bio spectrometer within a 10 mm cell. IR data
were collected on a Bruker VECTOR 22 FT-IR instrument using
neat CH2Cl2 solutions of the target compound that were evaporated
on NaCl plates. Elemental analyses were performed by Canadian
Microanalytical Service Ltd., Delta, British Columbia, Canada.
Synthesis of (K2-3-PiPr2-2-S-indene)Ir(COD). A solution of
1/3-PiPr2-2-StBu-indene (0.12 g, 0.38 mmol) in CH2Cl2 (1 mL) was
added dropwise to a magnetically stirred mixture of [(COD)IrCl]2
(0.13 g, 0.19 mmol) and CH2Cl2 (2 mL), causing an immediate
darkening of the solution to dark red. The reaction mixture was
magnetically stirred at ambient temperature for 0.25 h, followed
by treatment with Na(SiMe3)2 (0.070 g, 0.38 mmol) and continued
magnetic stirring for 20 h. Subsequent removal of the solvent and
other volatiles in Vacuo afforded a dark red solid that was extracted
into benzene followed by filtration through Celite and removal of
the solvent and volatiles in Vacuo. The residual solid was then
washed with pentane (3 × 2 mL) and dried in Vacuo, affording
(κ2-3-PiPr2-2-S-indene)Ir(COD) as an analytically pure, red solid
(0.13 g, 0.23 mmol, 61%). Anal. Calcd for C23H32IrPS: C, 49.00;
3
Hz, 1H, C5-H or C6-H), 7.28 (t, JHH ) 7.5 Hz, 1H, C5-H or
C6-H), 3.92 (s, 2H, C1(H)2), 3.12 (br m, 2H, P(CHMeaMeb)), 1.95
(s, 15H, C5Me5), 1.29 (d of d, 3JPH ) 18.5 Hz, 3JHH ) 7.0 Hz, 6H,
P(CHMeaMeb)), 1.22 (d of d, 3JPH ) 17.0 Hz, 3JHH ) 7.0 Hz, 6H,
P(CHMeaMeb)). 13C{1H} NMR (CD2Cl2): δ 177.8 (quaternary),
150.2 (quaternary), 140.3 (quaternary), 126.5 (quaternary), 126.8
(C5 or C6), 125.3 (C5 or C6), 124.8 (C4 or C7), 119.2 (C4 or C7),
96.7 (C5Me5), 40.9 (d, JPC ) 11.4 Hz, C1), 23.8 (br m, P(CH-
1
H, 5.72; N, 0.00. Found: C, 49.11; H, 5.62; N, <0.3. H NMR
(CDCl3): δ 7.27 (d, 3JHH ) 7.0 Hz, 1H, C4-H or C7-H), 7.22 (d,
3JHH ) 8.0 Hz, 1H, C4-H or C7-H), 7.17 (t, 3JHH ) 8.0 Hz, 1H,
3
C5-H or C6-H), 7.03 (t, JHH ) 7.5 Hz, 1H, C5-H or C6-H),
4.81 (m, 2H, COD), 3.93 (m, 2H, COD), 3.67 (s, 2H, C1(H)2),
3.01 (m, 2H, P(CHMeaMeb)), 2.31 (m, 2H, COD), 2.14 (m, 2H,
COD), 1.97 (m, 2H, COD), 1.82 (m, 2H, COD), 1.34 (d of d, 3JPH
) 16.0 Hz, 3JHH ) 7.5 Hz, 6H, P(CHMeaMeb)), 1.27 (d of d, 3JPH
2
MeaMeb)), 18.2 (P(CHMeaMeb)), 17.8 (d, JPC ) 2.8 Hz, P(CH-
3
MeaMeb)), 10.4 (C5Me5). 31P{1H} NMR (CD2Cl2): δ 64.9 (br s).
Synthesis of [2]+B(C6F5)4-. A protocol similar to that described
for the synthesis of [2]+OTf- was employed, using 1 (0.039 g,
0.062 mmol) and solid LiB(C6F5)4 ·2.5Et2O (0.054 g, 0.062 mmol;
) 15.5 Hz, JHH ) 7.0 Hz, 6H, P(CHMeaMeb)). 13C{1H} NMR
(CDCl3): δ 182.5 (quaternary), 149.5 (quaternary), 143.7 (quater-
nary), 129.9 (quaternary), 126.0 (C5 or C6), 124.5 (C4 or C7), 122.2
(C5 or C6), 118.4 (C4 or C7), 83.8 (d, 2JPC ) 12.5 Hz, CH (COD)),
-
in place of AgOTf), thereby affording [2]+B(C6F5)4 as an
analytically pure, dark blue solid (0.065 g, 0.051 mmol, 82%). Anal.
Calc for C49H35BF20IrPS: C, 46.32; H, 2.78; N, 0.00. Found: C,
(27) Hesp, K. D.; McDonald, R.; Ferguson, M. J.; Schatte, G.; Stradiotto,
M. Chem. Commun. 2008, DOI: 10.1039/B6.
9
16402 J. AM. CHEM. SOC. VOL. 130, NO. 48, 2008

Cp*M(κ2-P,S) Complexes
A R T I C L E S
3
46.19; H, 3.00; N, <0.3. 1H NMR (CD2Cl2): δ 7.47 (m, 1H, C4 or
C7), 7.41 (m, 1H, C4 or C7), 7.36-7.30 (m, 2H, C5 and C6), 3.96
(d, J ) 2.5 Hz, 2H, C1(H)2), 3.11 (m, 2H, P(CHMeaMeb)), 1.94
7.13 (t, JHH ) 7.5 Hz, 1H, C5-H or C6-H), 3.62 (m, 1H,
C1(Ha)(Hb)), 3.52 (m, 1H, C1(Ha)(Hb)), 3.24 (m, 1H, P(CH-
MeaMeb)), 2.34 (m, 1H, P(CHMecMed)), 1.92 (m, 15H, C5Me5),
4
3
3
3
(d, JPH ) 1.5 Hz, 15H, C5Me5), 1.30 (d of d, JPH ) 18.5 Hz,
3JHH ) 7.0 Hz, 6H, P(CHMeaMeb)), 1.20 (d of d, 3JPH ) 18.0 Hz,
3JHH ) 7.0 Hz, 6H, P(CHMeaMeb)). 13C{1H} NMR (CD2Cl2): δ
1.65 (br m, 9H, PMe3), 1.35 (d of d, JPH ) 13.5 Hz, JHH ) 7.0
Hz, 3H, P(CHMecMed)), 1.27 (d of d, 3JPH ) 13.0 Hz, 3JHH ) 7.0
Hz, 3H, P(CHMeaMeb)), 1.23 (d of d, 3JPH ) 11.0 Hz, 3JHH ) 7.5
Hz, 3H, P(CHMeaMeb)), 0.91 (d of d, 3JPH ) 15.0 Hz, 3JHH ) 7.0
Hz, 3H, P(CHMecMed)). 13C{1H} NMR (CDCl3): δ 176.6 (d, 2JPC
) 21.3 Hz, C2), 147.8 (d, JPC ) 7.8 Hz, C3a or C7a), 142.5 (d,
JPC ) 5.4 Hz, C3a or C7a), 129.7 (C3), 127.1 (Ar-C), 124.9
(Ar-C), 123.8 (C5 or C6), 118.6 (C4 or C7), 99.6 (C5Me5), 40.8
(d, 3JPC ) 10.4 Hz, C1), 30.7 (d, 1JPC ) 28.4 Hz, P(CHMecMed)),
2
177.8 (d, JPC ) 25.2 Hz, C2), 150.2 (d, JPC ) 10.1 Hz, C3a or
C7a), 140.1 (d, JPC ) 37.7 Hz, C3a or C7a), 134.7 (d, 1JPC ) 62.9
Hz, C3), 127.2 (C5 or C6), 125.8 (C4 or C7), 125.7 (C5 or C6),
3
120.5 (C4 or C7), 96.9 (C5Me5), 41.1 (d, JPC ) 11.4 Hz, C1),
1
23.9 (d, JPC ) 31.1 Hz, P(CHMeaMeb)), 18.3 (P(CHMeaMeb)),
2
18.0 (d, JPC ) 1.8 Hz, P(CHMeaMeb)), 10.7 (C5Me5). 31P{1H}
1
2
NMR (CD2Cl2): δ 65.2. UV-vis (THF): λmax 569 (ꢀ ) 1.49 ×
25.8 (d, JPC ) 34.5 Hz, P(CHMeaMeb)), 20.2 (d, JPC ) 6.8 Hz,
103), 673 (ꢀ ) 1.40 × 103).
P(CHMecMed)), 20.1 (P(CHMeaMeb)), 19.5 (d, JPC ) 3.4 Hz,
2
Synthesis of [2 ·CO]+OTf-. Compound [2]+OTf- was prepared
in situ by treatment of a solution of 1 (0.068 g, 0.11 mmol) in
CH2Cl2 (2 mL) with solid AgOTf (0.028 g, 0.11 mmol), causing
an immediate color change to dark blue accompanied by the
formation of a precipitate. The reaction mixture was stirred at
ambient temperature for 0.5 h followed by filtration through Celite
to remove the precipitate. The resulting dark blue CH2Cl2 solution
containing [2]+OTf- was transferred to a resealable flask and was
degassed by use of three consecutive freeze-pump-thaw cycles,
followed by backfilling with CO (ca. 1 atm), which effected an
immediate color change to bright orange. After 1 h of periodic
shaking of the reaction flask, the solvent and other volatiles were
removed in Vacuo, affording an oily orange solid that was triturated
with pentane (3 mL). Subsequent drying in Vacuo afforded
[2·CO]+OTf- as an analytically pure, bright orange powder (0.081
g, 0.10 mmol, 91%). Anal. Calcd for C27H35F3IrO4PS2: C, 42.23;
P(CHMeaMeb)), 18.0 (P(CHMecMed)), 17.2 (d, JPC ) 40.6 Hz,
1
PMe3), 9.8 (C5Me5). 31P{1H} NMR (CDCl3): δ 33.6 (d, JPP
)
2
i
2
28.3 Hz, Pr2PInd), -41.5 (d, JPP ) 28.3 Hz, PMe3).
Synthesis of 3 ·CH3CN. To a magnetically stirred suspension
of 1 (0.17 g, 0.27 mmol) in CH3CN (2 mL) was added solid
anhydrous K2CO3 (0.077 g, 0.55 mmol) followed by stirring at
ambient temperature for 48 h; the suspension darkened from orange
to brown during the reaction time. The reaction mixture was filtered
through Celite followed by removal of solvent and other volatiles
in Vacuo, affording a mixture of 3·CH3CN and another phosphorus-
containing product (ca. 92:8 on the basis of 31P NMR data).
Analytically pure 3·CH3CN was subsequently isolated by crystal-
lization from a concentrated CH3CN solution of the aforementioned
mixture stored at -35 °C (0.069 g, 0.11 mmol, 41%). From these
brown crystals was selected a sample that proved suitable for X-ray
diffraction analysis. Anal. Calcd for C27H37IrNPS: C, 51.39; H, 5.92;
1
1
H, 4.59; N, 0.00. Found: C, 42.12; H, 4.28; N, <0.3. H NMR
N, 2.22. Found: C, 51.37; H, 5.94; N, 2.39. H NMR (C6D6): δ
(CD2Cl2): δ 7.26 (d, 3JHH ) 7.5 Hz, 1H, C4-H or C7-H), 7.22 (t,
7.22-7.16 (m, 2H, C5 or C6 and C4 or C7), 7.05 (d, JHH ) 7.5
3
3JHH ) 7.5 Hz, 1H, C5-H or C6-H), 7.13 (d, 3JHH ) 7.5 Hz, 1H,
Hz, 1H, C4 or C7), 6.95 (t, 3JHH ) 7.5 Hz, 1H, C5 or C6), 6.81 (s,
1H, C3-H), 2.40 (m, 1H, P(CHMeaMeb)), 2.21 (m, 1H, P(CH-
MecMed)), 1.83 (s, 3H, NdCsCH3), 1.77 (d, 4JPH ) 2.0 Hz, 15H,
3
C4-H or C7-H), 7.10 (t, JHH ) 7.5 Hz, 1H, C5-H or C6-H),
3.61 (m, 2H, C1(H)2), 3.31 (m, 1H, P(CHMeaMeb)), 2.28 (m, 1H,
4
3
3
P(CHMecMed)), 2.15 (d, JPH ) 1.5 Hz, 15H, C5Me5), 1.37 (d of
C5Me5), 1.11 (d of d, JPH ) 14.0 Hz, JHH ) 7.0 Hz, 3H,
P(CHMeaMeb)), 0.91 (d of d, 3JPH ) 16.5 Hz, 3JHH ) 7.0 Hz, 3H,
P(CHMecMed)), 0.71 (d of d, 3JPH ) 15.5 Hz, 3JHH ) 7.0 Hz, 3H,
P(CHMeaMeb)), 0.49 (d of d, 3JPH ) 12.0 Hz, 3JHH ) 7.5 Hz, 3H,
P(CHMecMed)). 13C{1H} NMR (C6D6): δ 160.0 (d, 2JPC ) 7.4 Hz,
d, 3JPH ) 19.5 Hz, 3JHH ) 7.0 Hz, 3H, P(CHMecMed)), 1.24 (d of
d, 3JPH ) 19.5 Hz, 3JHH ) 7.0 Hz, 3H, P(CHMeaMeb)), 1.15 (d of
d, 3JPH ) 18.5 Hz, 3JHH ) 7.0 Hz, 3H, P(CHMeaMeb)), 0.95 (d of
3
3
d, JPH ) 18.5 Hz, JHH ) 7.0 Hz, 3H, P(CHMecMed)); 13C{1H}
2
2
2
NMR (CD2Cl2): δ 178.0 (d, JPC ) 18.5 Hz, CO), 166.6 (d, JPC
) 13.6 Hz, C2), 147.8 (d, JPC ) 8.3 Hz, C3a or C7a), 142.7 (d,
JPC ) 6.0 Hz, C3a or C7a), 130.0 (d, JPC ) 62.3 Hz, C3), 127.2
NdCsCH3), 158.8 (d, JPC ) 9.2 Hz, C2), 151.7 (d, JPC ) 4.3
Hz, C3a or C7a), 140.6 (d, JPC ) 4.9 Hz, C3a or C7a), 126.6 (C5
or C6), 122.4 (d, JPC ) 1.9 Hz, C4 or C7), 119.7 (d, JPC ) 1.5 Hz,
1
3
(C5 or C6), 125.0 (C4 or C7), 124.2 (C4 or C7), 118.3 (C5 or C6),
104.5 (C5Me5), 41.6 (d, 3JPC ) 10.9 Hz, C1), 29.6 (d, 1JPC ) 27.8
Hz, P(CHMecMed)), 25.4 (d, 1JPC ) 37.7 Hz, P(CHMeaMeb)), 19.1
C5 or C6), 117.9 (C4 or C7), 115.6 (d, JPC ) 3.5 Hz, C3), 92.2
1
(d, J ) 3.1 Hz, C5Me5), 24.1 (NdCsCH3), 22.1 (d, JPC ) 26.3
Hz, P(CHMecMed)), 21.2 (d, 2JPC ) 3.3 Hz, P(CHMecMed)), 21.1
2
1
2
(d, JPC ) 6.5 Hz, P(CHMecMed)), 18.6 (P(CHMeaMeb)), 18.5
(d, JPC ) 10.3 Hz, P(CHMeaMeb)), 19.6 (d, JPC ) 1.3 Hz,
(P(CHMeaMeb)), 17.3 (P(CHMecMed)), 9.7 (C5Me5). 31P{1H} NMR
(CD2Cl2): δ 42.6. FT-IR (NaCl; cm-1) ν(CO): 2053. Crystals
suitable for X-ray crystallographic analysis were grown by vapor
diffusion of diethyl ether into a concentrated CH2Cl2 solution of
[2·CO]+OTf- at ambient temperature.
P(CHMeaMeb)), 17.6 (d, JPC ) 3.0 Hz, P(CHMeaMeb)), 15.9 (d,
2
2JPC ) 4.5 Hz, P(CHMecMed)), 8.8 (C5Me5). 31P{1H} NMR (C6D6):
δ 91.6.
Synthesis of 4. A solution of (κ2-3-PiPr2-2-S-indene)Ir(COD)
(0.11 g, 0.20 mmol) in CH2Cl2 (4 mL) was degassed by use of
three freeze-pump-thaw cycles and was subsequently exposed
to an atmosphere of CO, which caused a gradual color change from
dark red to orange. After 0.75 h, 31P NMR data collected on an
aliquot of the reaction mixture confirmed the quantitative formation
of 4. Removal of the solvent caused a darkening of the solution to
dark brown, ultimately affording a brown solid that was extracted
into pentane (3 × 2 mL) and filtered through Celite. Removal of
the solvent and other volatiles afforded 4 as an analytically pure,
orange solid (0.041 g, 0.079 mmol, 39%). Anal. Calcd for
C17H20IrO2PS: C, 39.91; H, 3.94; N, 0.00. Found: C, 40.03; H, 4.25;
N, <0.3. 1H NMR (C6D6): δ 7.10 (t, 3JHH ) 8.0 Hz, 1H, C5-H or
-
Synthesis of [2 ·PMe3]+B(C6F5)4-. Compound [2]+B(C6F5)4
was prepared in situ by treatment of a solution of 1 (0.10 g, 0.17
mmol) in CH2Cl2 (2 mL) with solid LiB(C6F5)4 ·2.5Et2O (0.14 g,
0.17 mmol), causing an immediate color change to dark blue
accompanied by the formation of a precipitate. The reaction mixture
was stirred at ambient temperature for 0.5 h followed by filtration
through Celite to remove the precipitate. To the dark blue
supernatant solution containing [2]+B(C6F5)4- was added a 1.0 M
solution of PMe3 in toluene (198 µL, 0.20 mmol), which effected
an immediate color change to bright orange. After 1 h of magnetic
stirring, the solvent and other volatiles were removed in Vacuo,
affording an oily orange solid that was triturated with pentane (3
4
C6-H), 6.96-6.86 (m, 3H, Ar-H), 3.40 (d, JPC ) 2.0 Hz, 2H,
-
3
mL). Subsequent drying in Vacuo afforded [2·PMe3]+B(C6F5)4
C1(H)2), 2.40 (m, 2H, P(CHMeaMeb)), 1.15 (d of d, JPH ) 17.5
as an analytically pure, bright orange powder (0.22 g, 0.16 mmol,
94%). Anal. Calcd for C52H44BF20IrP2S: C, 46.40; H, 3.30; N, 0.00.
Found: C, 46.79; H, 3.43; N, <0.3. 1H NMR (CDCl3): δ 7.29-7.19
Hz, 3JHH ) 7.0 Hz, 6H, P(CHMeaMeb)), 0.89 (d of d, 3JPH ) 16.5
Hz, 3JHH ) 7.0 Hz, 6H, P(CHMeaMeb)). 13C{1H} NMR (C6D6): δ
2
2
181.6 (d, JPC ) 88.8 Hz, CO trans to P), 180.4 (d, JPC ) 30.7
3
2
(m, 2H, Ar-H), 7.17 (d, JHH ) 8.0 Hz, 1H, C4-H or C7-H),
Hz, C2), 178.5 (d, JPC ) 10.8 Hz, CO cis to P), 149.1 (d, JPC )
9
J. AM. CHEM. SOC. VOL. 130, NO. 48, 2008 16403

A R T I C L E S
Hesp et al.
6.8 Hz, C3a or C7a), 141.8 (d, JPC ) 5.5 Hz, C3a or C7a), 126.4
(C3), 126.6 (Ar-C), 124.3 (Ar-C), 122.5 (Ar-C), 117.0 (Ar-C),
(quaternary), 148.9 (quaternary), 148.4 (quaternary), 148.0 (qua-
ternary), 139.3 (quaternary), 135.9 (Ar-C), 135.4 (quaternary),
132.4 (Ar-C), 128.9 (Ar-C), 128.1 (Ar-C), 127.0 (Ar-C), 126.3
(Ar-C), 125.4 (Ar-C), 121.4 (Ar-C), 96.0 (C5Me5), 39.9 (d, 3JPC
3
1
42.2 (d, JPC ) 14.1 Hz, C1), 26.1 (d, JPC ) 33.0 Hz, P(CH-
2
MeaMeb)), 19.2 (d, JPC ) 2.6 Hz, P(CHMeaMeb)), 18.1 (P(CH-
MeaMeb)). 31P{1H} NMR (C6D6): δ 62.2. FT-IR (NaCl; cm-1
ν(CO): 2059, 1983.
)
) 8.9 Hz, C1), 27.1 (d, JPC ) 28.3 Hz, P(CHMecMed)), 23.4 (d,
1
2
1JPC ) 40.0 Hz, P(CHMeaMeb)), 18.1 (d, JPC ) 6.3 Hz, P(CH-
2
Reaction of 3 ·CH3CN with CO To Give 4. A benzene-d6
solution (2 mL) of 3·CH3CN (0.019 g, 0.030 mmol) was transferred
toaJ.YoungNMRtube,degassedbyuseofthreefreeze-pump-thaw
cycles, and subsequently exposed to an atmosphere of CO, which
caused an immediate color change from brown to orange. 31P NMR
analysis of the reaction mixture after 0.75 h confirmed the
quantitative consumption of 3·CH3CN along with the clean
formation of 4. 1H and 13C NMR analysis of the reaction mixture
also confirmed the formation of 4, along with a stoichiometric
equivalent amount of 1,2,3,4-tetramethylfulvene.20
MecMed)), 17.6 (d, JPC ) 3.8 Hz, P(CHMeaMeb)), 17.4 (P(CH-
MeaMeb) and P(CHMecMed)), 9.9 (C5Me5). 31P{1H} NMR
(CD2Cl2): δ 49.3. 29Si NMR (CD2Cl2): δ 3.6.
Synthesis of 6b. A protocol analogous to that described for the
synthesis of 6a was employed, using PhSiH3 (12 µL, 0.098 mmol)
in place of Ph2SiH2, with similar qualitative observations. Com-
pound 6b was isolated as an analytically pure, orange solid (0.10
g, 0.075 mmol, 77%). Anal. Calcd for C55H43BF20IrPSSi: C, 47.94;
1
H, 3.15; N, 0.00. Found: C, 47.81; H, 3.18; N, <0.3. H NMR
(CD2Cl2): δ 7.66-7.57 (m, 3H, Ar-H), 7.56-7.46 (m, 3H, Ar-H),
7.42-7.32 (m, 3H, Ar-H), 5.40 (m, 1H, Si(Ha)(Hb)), 4.99 (m, 1H,
Si(Ha)(Hb)), 3.51 (s, 2H, C1(H)2), 2.93 (m, 1H, P(CHMeaMeb)),
2.34 (m, 1H, P(CHMecMed)), 2.07 (m, 15H, C5Me5), 1.47 (d of d,
3JPH ) 13.5 Hz, 3JHH ) 7.0 Hz, 3H, P(CHMecMed)), 1.09 (d of d,
3JPH ) 19.5 Hz, 3JHH ) 6.5 Hz, 3H, P(CHMeaMeb)), 0.86 (d of d,
3JPH ) 17.5 Hz, 3JHH ) 7.0 Hz, 3H, P(CHMecMed)), 0.57 (d of d,
Synthesis of 5. Compound [2]+OTf- was prepared in situ by
treatment of a solution of 1 (0.098 g, 0.16 mmol) in CH2Cl2 (2
mL) with solid AgOTf (0.040 g, 0.16 mmol), followed by magnetic
stirring at ambient temperature, during which time the solution
turned dark blue with the concomitant formation of a precipitate.
After 0.5 h of stirring, the precipitate was removed by filtration
through Celite. To the dark blue supernatant solution was added
Ph2SiH2 (29 µL, 0.16 mmol), which caused an immediate color
change to orange. After 1 h of magnetic stirring, the solvent and
other volatiles were removed in Vacuo followed by washing with
pentane (2 mL). Subsequent drying in Vacuo afforded an orange
solid that was extracted into pentane (2 × 2 mL). Concentration of
the pentane solution and storage at -35 °C afforded 5 as analytically
pure, orange crystals (0.041 g, 0.068 mmol, 44%). Anal. Calcd for
C25H36IrPS: C, 50.74; H, 6.13; N, 0.00. Found: C, 50.53; H, 5.94;
N, <0.3. 1H NMR (C6D6): δ 7.19-7.12 (m, 2H, Ar-H), 6.94-6.87
3
3JPH ) 17.5 Hz, JHH ) 7.0 Hz, 3H, P(CHMeaMeb)), -15.02 (d,
2JPH ) 34.0 Hz, Ir-H). 13C{1H} NMR (CD2Cl2): δ 153.4
(quaternary), 149.4 (quaternary), 149.0 (quaternary), 139.4 (qua-
ternary), 135.7 (Ar-C), 132.8 (Ar-C), 129.1 (Ar-C), 127.3
(Ar-C), 126.7 (Ar-C), 125.7 (Ar-C), 121.8 (Ar-C), 96.4
3
1
(C5Me5), 39.3 (d, JPC ) 9.1 Hz, C1), 27.1 (d, JPC ) 28.4 Hz,
P(CHMecMed)), 23.8 (d, 1JPC ) 39.9 Hz, P(CHMeaMeb)), 18.3 (d,
2JPC ) 6.2 Hz, P(CHMecMed)), 18.2 (P(CHMeaMeb)), 17.9 (d, 2JPC
) 4.5 Hz, P(CHMeaMeb)), 17.8 (P(CHMecMed)), 10.1 (C5Me5).
31P{1H} NMR (CD2Cl2): δ 49.5. 29Si NMR (CD2Cl2): δ 94.1.
Synthesis of 7. Compound 6a (prepared in situ employing the
protocols described above using 1 (0.098 g, 0.16 mmol), LiB-
(C6F5)4 ·2.5Et2O (0.14 g, 0.16 mmol), and Ph2SiH2 (29 µL, 0.16
mmol)) was dissolved in diethyl ether (2 mL), and the resulting
solution was stored at ambient temperature for 24 h, during which
time 7 precipitated from the solution as an analytically pure, orange
crystalline solid (0.12 g, 0.092 mmol, 58% based on 1). Anal. Calcd
for C51H41BF20IrPS: C, 47.10; H, 3.18; N, 0.00. Found: C, 47.08;
2
(m, 2H, Ar-H), 3.50 (d, JHH ) 22.0 Hz, 1H, C1(Ha)(Hb)), 3.42
(d, 2JHH ) 22.0 Hz, 1H, C1(Ha)(Hb)), 2.63 (m, 1H, P(CHMeaMeb)),
2.00 (m, 1H, P(CHMecMed)), 1.82 (s, 15H, C5Me5), 1.21 (d of d,
3JPH ) 12.5 Hz, 3JHH ) 7.0 Hz, 3H, P(CHMecMed)), 1.03 (d of d,
3JPH ) 16.5 Hz, 3JHH ) 7.0 Hz, 3H, P(CHMecMed)), 0.95 (d of d,
3JPH ) 16.5 Hz, 3JHH ) 7.0 Hz, 3H, P(CHMeaMeb)), 0.87 (d of d,
3
3JPH ) 14.5 Hz, JHH ) 7.0 Hz, 3H, P(CHMeaMeb)), -15.74 (d,
2JPH ) 37.5 Hz, 1H, Ir-H). 13C{1H} NMR (C6D6): δ 182.4 (d,
2JPC ) 24.5 Hz, C2), 147.9 (d, JPC ) 7.0 Hz, C3a or C7a), 144.9
H, 3.24; N, <0.3. H NMR (CD2Cl2): δ 7.60 (d, JHH ) 7.5 Hz,
1
3
1
3
(d, JPC ) 4.4 Hz, C3a or C7a), 128.6 (d, JPC ) 62.1 Hz, C3),
1H, C5-H or C6-H), 7.50 (d, JHH ) 7.5 Hz, 1H, C5-H or
125.9 (Ar-C), 123.7 (Ar-C), 120.6 (Ar-C), 116.2 (Ar-C), 91.4
C6-H), 7.46-7.36 (m, 2H, C4-H and C7-H), 3.65 (m, 2H,
C1(H)2), 3.09-2.93 (m, 2H, P(CHMeaMeb) and S(CHaHb)CH3),
2.59 (m, 1H, S(CHaHb)CH3), 2.35 (m, 1H, P(CHMecMeb)), 2.11
(s, 15H, C5Me5), 1.49 (d of d, 3JPH ) 14.0 Hz, 3JHH ) 7.0 Hz, 3H,
P(CHMecMed)), 1.16 (d of d, 3JPH ) 19.5 Hz, 3JHH ) 7.0 Hz, 3H,
P(CHMeaMeb)), 1.02 (t, 3JHH ) 7.5 Hz, 3H, SCH2CH3), 0.90 (d of
d, 3JPH ) 14.0 Hz, 3JHH ) 7.0 Hz, 3H, P(CHMecMed)), 0.86 (d of
d, 3JPH ) 13.5 Hz, 3JHH ) 7.0 Hz, 3H, P(CHMeaMeb)), -15.36 (d,
2JPH ) 32.5 Hz, 1H, Ir-H). 13C{1H} NMR (CD2Cl2): δ 157.9 (d,
2JPC ) 18.9 Hz, C2), 149.5 (d, JPC ) 6.0 Hz, C3a or C7a), 138.9
3
1
(C5Me5), 40.4 (d, JPC ) 10.6 Hz, C1), 28.7 (d, JPC ) 25.4 Hz,
1
P(CHMecMed)), 22.6 (d, JPC ) 42.8 Hz, P(CHMeaMeb)), 18.4
(P(CHMeaMeb)), 18.2 (d, 2JPC ) 5.7 Hz, P(CHMecMed)), 17.9 (d,
2JPC ) 4.7 Hz, P(CHMeaMeb)), 17.3 (d, 2JPC ) 3.6 Hz, P(CHMec-
Med)), 9.4 (C5Me5). 31P{1H} NMR (C6D6): δ 43.8.
Synthesis of 6a. A magnetically stirred solution of [2]+B-
(C6F5)4- (0.12 g, 0.098 mmol) in CH2Cl2 (2 mL) was treated with
Ph2SiH2 (18 µL, 0.098 mmol), which caused an immediate color
change from dark blue to orange; 31P NMR analysis of the reaction
mixture revealed the quantitative formation of 6a. After 0.5 h of
magnetic stirring, the CH2Cl2 was removed in Vacuo followed by
the addition of benzene (2 mL), which caused the separation of a
red oil that was isolated by removal of the benzene supernatant by
use of a Pasteur pipet. The red oil was washed with benzene (3 ×
2 mL) followed by drying in Vacuo to afford 6a as an analytically
pure, orange solid (0.097 g, 0.067 mmol, 68%). Anal. Calcd for
C61H47BF20IrPSSi: C, 50.36; H, 3.26; N, 0.00. Found: C, 50.11; H,
3.45; N, <0.3. 1H NMR (CD2Cl2): δ 7.67-7.15 (m, 14H, Ar-H),
(C3a or C7a), 127.6 (C5 or C6), 127.2 (C5 or C6), 126.0 (C4 or
3
C7), 125.8 (C3), 122.3 (C4 or C7), 96.8 (C5Me5), 37.7 (d, JPC
)
6.2 Hz, C1), 37.6 (SCH2CH3), 26.9 (d, 1JPC ) 29.4 Hz, P(CHMec-
1
Med)), 24.2 (d, JPC ) 39.2 Hz, P(CHMeaMeb)), 18.6 (P(CH-
MeaMeb)), 18.3 (d, 2JPC ) 6.2 Hz, P(CHMecMed)), 18.0 (d, 2JPC
)
4.4 Hz, P(CHMeaMeb)), 17.9 (P(CHMecMed)), 11.6 (SCH2CH3),
10.1 (C5Me5). 31P{1H} NMR (CD2Cl2): δ 48.6. Crystals suitable
for X-ray crystallographic analysis were grown from a concentrated
diethyl ether solution of 7 at ambient temperature.
2
5.52 (s, 1H, Si-H), 3.28 (d, JHH ) 23.5 Hz, 1H, C1(Ha)(Hb)),
Synthesis of 8. A solution of 1/3-PiPr2-2-StBu-indene (0.10 g,
0.32 mmol) in CH2Cl2 (2 mL) was added dropwise to a suspension
of [Cp*RhCl2]2 (0.097 g, 0.16 mmol) in CH2Cl2 (2 mL), resulting
in an immediate darkening of the solution. The reaction mixture
was magnetically stirred at ambient temperature for 16 h prior to
removal of the solvent and other volatiles in Vacuo. The residual
solid was washed with pentane (3 × 2 mL) and dried in Vacuo to
afford 8 as an analytically pure, light brown solid (0.16 g, 0.30
2
3.12 (d, JHH ) 24.0 Hz, 1H, C1(Ha)(Hb)), 2.75 (m, 1H, P(CH-
MeaMeb)), 2.22 (m, 1H, P(CHMecMed)), 2.00 (s, 15H, C5Me5), 1.35
(d of d, 3JPH ) 14.0 Hz, 3JHH ) 7.5 Hz, 3H, P(CHMecMed)), 0.94
(d of d, 3JPH ) 19.5 Hz, 3JHH ) 7.0 Hz, 3H, P(CHMeaMeb)), 0.77
(d of d, 3JPH ) 18.0 Hz, 3JHH ) 7.5 Hz, 3H, P(CHMecMed)), 0.076
(d of d, 3JPH ) 18.0 Hz, 3JHH ) 6.5 Hz, 3H, P(CHMeaMeb)), -15.12
(d, 2JPH ) 50.0 Hz, 1H, Ir-H). 13C{1H} NMR (CD2Cl2): δ 152.4
9
16404 J. AM. CHEM. SOC. VOL. 130, NO. 48, 2008

Cp*M(κ2-P,S) Complexes
A R T I C L E S
mmol, 94%). Anal. Calcd for C25H35ClRhPS: C, 55.92; H, 6.57;
1H, Rh-H). 13C NMR data on the basis of 1H-13C HMBC/HSQC
experiments (THF-d8): δ 135.0 (Ar-C), 134.7 (Ar-C), 131.7
(Ar-C), 129.1 (Ar-C), 129.0 (Ar-C), 128.8 (Ar-C), 126.5 (C5
or C6), 123.9 (C4 or C7), 121.6 (C5 or C6), 117.5 (C4 or C7),
42.8 (C1), 29.1 (P(CHMe2)), 23.9 (P(CHMe2)), 19.3 (P(CHMeMe)),
19.2 (P(CHMeMe)), 18.8 (P(CHMeMe)), 18.6 (P(CHMeMe)), 10.5
1
N, 0.00. Found: C, 55.88; H, 6.52; N, <0.3. H NMR (CDCl3): δ
7.19 (d, 3JHH ) 7.5 Hz, 1H, C4-H or C7-H), 7.13 (t, 3JHH ) 8.0
3
Hz, 1H, C5-H or C6-H), 7.06 (d, JHH ) 7.5 Hz, 1H, C4-H or
3
C7-H), 6.96 (t, JHH ) 7.5 Hz, 1H, C5-H or C6-H), 3.63 (m,
1H, C1(Ha)(Hb)), 3.54 (m, 1H, C1(Ha)(Hb)), 3.19 (m, 1H, P(CH-
MeaMeb)), 2.30 (m, 1H, P(CHMecMed)), 1.77 (d, JPC ) 3.0 Hz,
1
(C5Me5). 31P{1H} NMR (THF-d8): δ 77.4 (d, JRhP ) 143.7 Hz).
3
3
15H, C5Me5), 1.51 (d of d, JPH ) 15.0 Hz, JHH ) 7.0 Hz, 3H,
P(CHMeaMeb)), 1.45-1.37 (m, 6H, P(CHMeaMeb) and P(CHMec-
Synthesis of 11. Method A: To a magnetically stirred solution
of 3 · CH3CN (0.066 g, 0.10 mmol) in THF (2 mL) was added
Ph2SiH2 (19 µL, 0.10 mmol), which effected an immediate color
change from dark red to orange. The reaction mixture was
magnetically stirred at ambient temperature for 2 h, at which time
31P NMR data collected on an aliquot of the reaction mixture
indicated the complete consumption of 3·CH3CN and the appear-
ance of two new phosphorus-containing products (11a,b). The
solvent was removed in Vacuo, affording an orange residue that
was extracted into pentane (3 mL). Removal of the pentane afforded
11 as a mixture of diastereomers (11a,b) in a 3:1 ratio (0.049 g,
0.064 mmol, 64%). Method B: A mixture of 1 (0.053 g, 0.085
mmol) and Ph2SiH2 (16 µL, 0.085 mmol) in THF (2 mL) was cooled
to -35 °C followed by the dropwise addition of a solution of
NaN(SiMe3)2 (0.016 g, 0.085 mmol) in THF (1 mL), which caused
a rapid color change from orange to dark brown followed by an
immediate return to orange. The reaction mixture was magnetically
stirred and allowed to warm to ambient temperature followed by
magnetic stirring for 3 h, at which time 31P NMR data collected
on an aliquot of the reaction mixture indicated complete consump-
tion of 1 and the formation of 11a,b. The solvent was removed in
Vacuo, affording an orange residue that was extracted into pentane
(3 mL). Removal of the pentane afforded 11 as a mixture of
diastereomers (11a,b; similar to that observed by use of Method
A) in a 4:1 ratio (0.052 g, 0.067 mmol, 79%). Anal. Calcd for
C37H46IrPSSi: C, 57.41; H, 5.99; N, 0.00. Found: C, 57.09; H, 6.20;
N, <0.3. Diastereomer 11a: 1H NMR (C6D6): δ 7.55 (m, 2H,
Ar-H), 7.38 (m, 2H, Ar-H), 7.21-6.99 (m, 8H, Ar-H), 6.88 (m,
3
3
Med)), 1.10 (d of d, JPH ) 16.0 Hz, JHH ) 7.0 Hz, 3H,
P(CHMecMed)). 13C{1H} NMR (CDCl3): δ 179.5 (d, JPC ) 24.3
2
Hz, C2), 147.7 (d, JPC ) 6.9 Hz, C3a or C7a), 145.8 (C3a or C7a),
126.2 (C5 or C6), 123.5 (C4 or C7), 121.9 (C5 or C6), 117.6 (C4
or C7), 98.8 (d of d, 1JRhC ) 5.9 Hz, 2JPC ) 3.0 Hz, C5Me5), 43.1
(d of d, 3JPC ) 11.8 Hz, 3JRhC ) 1.4 Hz, C1), 29.4 (d of d, 1JPC
)
19.6 Hz, 2JRhC ) 1.4 Hz, P(CHMecMed)), 26.4 (d, 1JPC ) 28.9 Hz,
2
P(CHMeaMeb)), 20.5 (P(CHMeaMeb)), 20.2 (d, JPC ) 7.5 Hz,
2
P(CHMeaMeb)), 19.7 (d, JPC ) 6.8 Hz, P(CHMecMed)), 18.7 (d,
2JPC ) 2.1 Hz, P(CHMecMed)), 9.6 (C5Me5). 31P{1H} NMR
1
(CDCl3): δ 65.7 (d, JRhP ) 141.7 Hz).
Formation of [9]+B(C6F5)4-. To a magnetically stirred solution
of 8 (0.023 g, 0.042 mmol) in CD2Cl2 (2 mL) was added solid
LiB(C6F5)4 ·2.5Et2O (0.037 g, 0.042 mmol), which caused an
immediate color change of the reaction mixture to dark green. After
0.25 h, 31P NMR analysis of the reaction mixture revealed the
complete consumption of 8 and the presence of a major phosphorus-
containing product (ca. 75% of mixture, 31P NMR) that we assign
as [9]+B(C6F5)4-. Although we have thus far not been able to
isolate [9]+B(C6F5)4- in analytically pure form due to the apparent
1
instability of this complex in solution and upon workup, H and
13C NMR characterization data obtained in situ are consistent with
the Cs-symmetric nature of the target complex. Alternative reactions
conducted in THF-d8 afforded red reaction mixtures in which the
-
transformation of 8 into [9]+B(C6F5)4 in a similar fashion was
observed by use of NMR methods. 1H NMR (CD2Cl2): δ 7.47 (d,
3JHH ) 7.5 Hz, 1H, C4-H or C7-H), 7.36-7.29 (m, 2H, Ar-H),
7.25 (d of t, 3JHH ) 7.0 Hz, 4JHH ) 1.5 Hz, 1H, C5-H or C6-H),
3.89 (d, 4JPH ) 2.0 Hz, 2H, C1(H)2), 2.96 (m, 2H, P(CHMeaMeb)2),
3
1H, Ar-H), 6.82 (m, 1H, Ar-H), 5.66 (d, JHH ) 1.0 Hz, 1H,
Si-H), 4.18 (m, 1H, C1-H), 2.60 (m, 1H, P(CHMeaMeb)),
1.86-1.79 (m, 16H, C5Me5 and P(CHMecMed)), 1.06 (d of d, 3JPH
) 12.5 Hz, 3JHH ) 7.0 Hz, 3H, P(CHMecMed)), 0.91 (d of d, 3JPH
) 16.0 Hz, 3JHH ) 6.5 Hz, 3H, P(CHMeaMeb)), 0.84 (d of d, 3JPH
) 17.5 Hz, 3JHH ) 6.5 Hz, 3H, P(CHMeaMeb)), 0.37 (d of d, 3JPH
4
3
1.86 (d, JPH ) 2.0 Hz, 15H, C5Me5), 1.32 (d of d, JPH ) 18.5
Hz, 3JHH ) 7.0 Hz, P(CHMeaMeb)2), 1.22 (d of d, 3JPH ) 16.5 Hz,
3JHH ) 7.0 Hz, P(CHMeaMeb)2). 13C{1H} NMR (CD2Cl2): δ 175.0
(C2), 149.5 (C3a or C7a), 141.4 (C3a or C7a), 131.7 (C3), 127.2
(Ar-C), 125.3 (C5 or C6), 125.1 (C4 or C7), 120.4 (Ar-C), 102.6
(d, 1JRhC ) 5.2 Hz, C5Me5), 42.3 (d, 3JPC ) 12.8 Hz, C1), 24.9 (d,
1JPC ) 24.0 Hz, P(CHMeaMeb)2), 18.6 (P(CHMeaMeb)2), 18.4 (d,
2JPC ) 4.0 Hz, P(CHMeaMeb)2), 10.9 (C5Me5). 31P{1H} NMR
) 17.0 Hz, 3JHH ) 7.0 Hz, 3H, P(CHMecMed)), -15.81 (d, 2JPH
)
)
2
37.0 Hz, 1H, Ir-H). 13C{1H} NMR (C6D6): δ 182.8 (d, JPC
25.5 Hz, C2), 148.5 (d, 2JPC ) 7.5 Hz, C3a or C7a), 144.5 (d, 2JPC
) 4.9 Hz, C3a or C7a), 135.7 (Ar-C), 135.2 (Ar-C), 132.9 (SiPh2-
quaternary), 130.8 (SiPh2-quaternary), 129.0 (Ar-C), 128.7 (Ar-C),
127.1 (Ar-C), 127.0 (d, 1JPC ) 23.3 Hz, C3), 126.9 (Ar-C), 124.8
(Ar-C), 123.8 (Ar-C), 119.7 (Ar-C), 116.2 (Ar-C), 91.4 (d, 2JPC
1
(CD2Cl2): δ 69.3 (d, JRhP ) 172.0 Hz).
Formation of 10. Treatment of a magnetically stirred THF-d8
-
3
1
solution of [9]+B(C6F5)4 (0.042 mmol scale; prepared in situ as
) 3.0 Hz, C5Me5), 44.2 (d, JPC ) 9.8 Hz, C1), 27.8 (d, JPC )
outlined above) with Ph2SiH2 (7.8 µL, 0.042 mmol) caused an
immediate color change to dark orange. After 0.25 h, 31P NMR
analysis of the reaction mixture revealed the complete consumption
26.3 Hz, P(CHMecMed)), 22.4 (d, 1JPC ) 42.8 Hz, P(CHMeaMeb)),
18.3 (P(CHMeaMeb)), 17.9 (d, 2JPC ) 5.9 Hz, P(CHMecMed)), 17.8
2
2
(d, JPC ) 4.8 Hz, P(CHMeaMeb)), 16.6 (d, JPC ) 4.3 Hz,
P(CHMecMed)), 9.3 (C5Me5). 31P{1H} NMR (C6D6): δ 42.3. 29Si
NMR (C6D6): δ 89.1. Diastereomer 11b: 1H NMR (C6D6): δ
7.59-7.57 (m, 2H, Ar-H), 7.37-7.35 (m, 2H, Ar-H), 7.13-6.99
-
of [9]+B(C6F5)4 and the presence of a major phosphorus-
containing product (ca. 80% of mixture, 31P NMR) that we assign
as 10. Although we have thus far not been able to isolate 10 in
analytically pure form due to the apparent instability of this complex
in solution and upon workup, NMR characterization data obtained
in situ are consistent with the identity of 10 as being the Rh
analogue of the isolable Ir complex 6a. 1H NMR (THF-d8): δ
3
(m, 9H, Ar-H), 6.84-6.81 (m, 1H, Ar-H), 5.72 (d, JHH ) 1.0
Hz, 1H, Si-H), 4.21 (m, 1H, C1-H), 2.48 (m, 1H, P(CHMeaMeb)),
1.99 (m, 1H, P(CHMecMed)), 1.79 (s, 15H, C5Me5), 1.19 (d of d,
3JPH ) 12.5 Hz, 3JHH ) 7.0 Hz, 3H, P(CHMecMed)), 0.99 (d of d,
3JPH ) 16.0 Hz, 3JHH ) 7.0 Hz, 3H, P(CHMecMed)), 0.86 (d of d,
3JPH ) 13.0 Hz, 3JHH ) 6.5 Hz, 3H, P(CHMeaMeb)), 0.41 (d of d,
7.78-7.73 (m, Ar-H), 7.60-7.55 (m, 2H, Ar-H), 7.54-7.49 (m,
3
Ar-H), 7.16-7.10 (m, 2H, C4-H and C7-H), 7.08 (t, JHH
)
7.0 Hz, 1H, C5-H or C6-H), 6.87 (t, 3JHH ) 7.5 Hz, 1H, C5-H
or C6-H), 5.79 (s, 1H, S--H), 3.42 (m, 1H, C1(Ha)(Hb)), 3.33
(m, 1H, C1(Ha)(Hb)), 2.99 (m, 1H, P(CHMe2)), 2.43 (m, 1H,
3JPH ) 16.0 Hz, JHH ) 7.0 Hz, 3H, P(CHMeaMeb)), -16.04 (d,
3
2JPH ) 37.5 Hz, 1H, Ir-H). 13C{1H} NMR (C6D6): δ 181.4 (d,
2JPC ) 25.2 Hz, C2), 148.3 (d, JPC ) 7.5 Hz, C3a or C7a), 144.0
(d, JPC ) 4.7 Hz, C3a or C7a), 135.6 (Ar-C), 135.2 (Ar-C), 132.5
(SiPh-quaternary), 130.3 (SiPh-quaternary), 128.8 (Ar-C), 128.7
3
P(CHMe2)), 1.99 (m, 15H, C5Me5), 1.41 (d of d, JPH ) 12.0 Hz,
3JHH ) 7.0 Hz, P(CHMeMe)), 1.20 (d of d, JPH ) 14.5 Hz, JHH
3
3
) 7.5 Hz, P(CHMeMe)), 1.17 (d of d, 3JPH ) 11.5 Hz, 3JHH ) 7.0
(Ar-C), 127.3 (d, JPC ) 25.9 Hz, C3), 127.0 (Ar-C), 126.6
1
3
3
Hz, P(CHMeMe)), 1.02 (d of d, JPH ) 16.5 Hz, JHH ) 7.0 Hz,
(Ar-C), 124.6 (Ar-C), 123.5 (Ar-C), 119.8 (Ar-C), 116.4
1
2
2
3
P(CHMeMe)), -12.81 (d of d, JRhP ) 45.0 Hz, JPH ) 20.0 Hz,
(Ar-C), 91.4 (d, JPC ) 3.0 Hz, C5Me5), 43.9 (d, JPC ) 9.7 Hz,
9
J. AM. CHEM. SOC. VOL. 130, NO. 48, 2008 16405

A R T I C L E S
Hesp et al.
C1), 28.8 (d, 1JPC ) 25.4 Hz, P(CHMecMed)), 22.8 (d, 1JPC ) 42.8
Hz, P(CHMeaMeb)), 18.4 (d, 2JPC ) 5.7 Hz, P(CHMecMed)), 18.0
(d, 2JPC ) 4.8 Hz, P(CHMeaMeb)), 17.9 (P(CHMeaMeb)), 17.2 (d,
2JPC ) 3.8 Hz, P(CHMecMed)), 9.4 (C5Me5). 31P{1H} NMR (C6D6)
δ 43.2. 29Si NMR δ 89.1. A crystal of one of the diastereomers of
11 suitable for X-ray crystallographic analysis was grown by
evaporation of a concentrated diethyl ether solution of 11a,b at
ambient temperature.
-0.180 1] axis in real space and about the [-0.002 0 1] axis in
reciprocal space. Integrated intensities for the reflections from the
two components were written into a SHELXL-93 HKLF 5 reflection
file by use of the data integration program SAINT (version 7.06A),
employing all reflection data (exactly overlapped, partially over-
lapped, and nonoverlapped). Each structure was refined by use of
2
full-matrix least-squares procedures (on F2) with R1 based on Fo
2
2
2
g 2σ(Fo ) and wR2 based on Fo g -3σ(Fo ). Anisotropic
displacement parameters were employed throughout for the non-H
atoms, and all H-atoms were added at calculated positions (with
the exception of Si-H and Ir-H, which were located in the
difference map) and refined by use of a riding model employing
isotropic displacement parameters based on the isotropic displace-
ment parameter of the attached atom. For each of 7 and 11, the
near-zero final refined value of the Flack28 absolute structure
parameter (-0.005(3) for 7; 0.002(5) for 11) supported that the
correct absolute structure had been chosen. Additional crystal-
lographic information is provided in the accompanying crystal-
lographic information file (CIF).
General Protocol for Ketone Hydrosilylation Experiments.
Representative protocols for reactions involving acetophenone and
PhSiH3 are presented. Within a glovebox, a glass vial was charged
with a stir-bar, 8 (2.1 mg, 0.004 mmol), LiB(C6F5)4 ·2.5Et2O (3.5
mg, 0.004 mmol), THF (2 mL), and acetophenone (23.4 µL, 0.2
mmol). The resulting solution was stirred for 10 min followed by
the addition of PhSiH3 (37.0 µL, 0.3 mmol). The resulting mixture
was magnetically stirred for 5 h at ambient temperature, at which
time the contents of the vial were cooled to 0 °C followed by the
addition of acetone (5 mL) and 1 M HCl(aq) (ca. 5 mL). The
mixture was stirred for 2 h at 0 °C followed by 0.5 h at ambient
temperature. An aqueous solution of saturated sodium bicarbonate
was added (ca. 5 mL), and the reaction mixture was stirred until
no more gas evolution was observed (ca. 0.25 h). The reaction
mixture was extracted with Et2O (2 × 5 mL). The combined organic
layers were dried over Na2SO4, filtered through a plug of silica,
and concentrated in Vacuo. This solution was transferred to a GC
vial and sealed. Products were identified by comparison to the 1H
NMR of authentic samples, while quantitative data (average of at
least two independent experiments) were obtained from GC-FID
analysis using a Supelco BETA-DEX 120 column.
Acknowledgment. We thank the Natural Sciences and Engi-
neering Research Council (NSERC) of Canada (including a
Discovery Grant for M.S. and a Canada Graduate Scholarship for
K.D.H.), 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. Michael
Lumsden and Katherine Robertson (Atlantic Region Magnetic
Resonance Center, Dalhousie) for assistance in the acquisition of
NMR data.
Crystallographic Solution and Refinement Details. For each
of the crystallographically characterized compounds reported herein,
single-crystal X-ray diffraction data were obtained at 193((2) K
on a Bruker PLATFORM/SMART 1000 CCD diffractometer using
graphite-monochromated Mo KR (λ ) 0.71073 Å) radiation,
employing a sample that was mounted in inert oil and transferred
to a cold gas stream on the diffractometer. Programs for diffrac-
tometer operation, data collection, and data reduction were supplied
by Bruker. Gaussian integration (for 1 and 11), TWINABS (for
[2·CO]+OTf-), or SADABS (for 3·CH3CN and 7) was employed
as the absorption correction method, and the structure was solved
by use of a Patterson search/structure expansion (for 1 and
3·CH3CN) or direct methods (for [2·CO]+OTf-, 7, and 11). The
crystal of [2·CO]+OTf- used for data collection was found to
display nonmerohedral twinning, and both components of the twin
were indexed by use of the program CELL_NOW (Bruker AXS
Inc., Madison, WI, 2004). The second twin component can be
related to the first component by 180° rotation about the [-0.390
Note Added in Proof. While this manuscript was under review,
a related study of Cp*Ir(PS) complexes was reported: Ohki, Y.;
Sakamoto, M.; Tatsumi, K. J. Am. Chem. Soc. 2008, 130, 11610.
Supporting Information Available: X-ray crystallographic
information files (CIF) for 1, [2·CO]+OTf-, 3·CH3CN, 7, and
11, as well as in situ NMR spectra for the reactions involving
-
the formation of [9]+B(C6F5)4 and 10. This material is
available free of charge via the Internet at http://pubs.acs.org.
JA8062277
(28) The Flack absolute structure parameter will refine to a value near zero
if the structure is in the correct configuration and will refine to a value
near one for the inverted configuration: (a) Flack, H. D.; Bernardinelli,
G. Acta Crystallogr. 1999, A55, 908. (b) Flack, H. D.; Bernardinelli,
G. J. Appl. Crystallogr. 2000, 33, 1143.
9
16406 J. AM. CHEM. SOC. VOL. 130, NO. 48, 2008