POP-pincer silyl complexes of group 9: Rhodium versus iridium

Article abstract of DOI:10.1021/ic401931y

9,9-Dimethyl-4,5-bis(diisopropylphosphino)xanthene (xant(P ⁱPr₂)₂) derivatives RhCl{xant(P ⁱPr₂)₂} (1) and IrHCl{xant(PⁱPr ₂)[ⁱPrPCH(Me)CH₂]} (2) react with diphenylsilane and triethylsilane to give the saturated d⁶-compounds RhHCl(SiR₃){xant(PⁱPr₂)₂} (SiR ₃ = SiHPh₂ (3), SiEt₃ (4)) and IrHCl(SiR ₃){xant(PⁱPr₂)₂} (SiR₃ = SiHPh₂ (5), SiEt₃ (6)). Complexes 3 and 5 undergo a Cl/H position exchange process via the MH{xant(PⁱPr₂) ₂} (M = Rh (8), Ir (E)) intermediates. The rhodium complex 3 affords the square planar d⁸-silyl derivative Rh(SiClPh₂) {xant(PⁱPr₂)₂} (7), whereas the iridium derivative 5 gives IrH₂(SiClPh₂){xant(PⁱPr ₂)₂} (9), which is stable. In agreement with the formation of 7, the reactions of 8 with silanes are a general method to prepare square planar d⁸-rhodium-silyl derivatives. Thus, the addition of triethylsilane and triphenylsilane to 8 initially leads to the dihydrides RhH₂(SiR₃){xant(PⁱPr₂)₂} (SiR₃ = SiEt₃ (10), SiPh₃ (11)), which lose molecular hydrogen to afford Rh(SiR₃){xant(PⁱPr ₂)₂} (SiR₃ = SiEt₃ (12), SiPh ₃ (13)). Treatment of 7 with NaBAr^F₄· 2H₂O leads to the cationic five-coordinate d⁶-species [RhH{Si(OH)Ph₂}{xant(PⁱPr₂)₂}] BAr^F₄ (14) through a silylene intermediate. According to the participation of the latter in the formation of 14, this cation is an efficient catalyst precursor for the monoalcoholysis of diphenylsilane with a wide range of alcohols, reaching turnover frequencies at 50% of conversion between 4000 and 76 500 h^-1. The X-ray structures of 3, 6, 7, 9, 12, and 14 are also reported.

Full text of DOI:10.1021/ic401931y

Article
pubs.acs.org/IC
POP-Pincer Silyl Complexes of Group 9: Rhodium versus Iridium
Miguel A. Esteruelas,* Montserrat Olivan, and Andrea Velez
́
́
́ ́ ́
Departamento de Química Inorganica, Instituto de Síntesis Química y Catalisis Homogenea (ISQCH), Universidad de Zaragoza -
CSIC, 50009 Zaragoza, Spain
S
* Supporting Information
ABSTRACT: 9,9-Dimethyl-4,5-bis(diisopropylphosphino)-
xanthene (xant(PiPr2)2) derivatives RhCl{xant(PiPr2)2} (1)
and IrHCl{xant(PiPr2)[iPrPCH(Me)CH2]} (2) react with
diphenylsilane and triethylsilane to give the saturated d6-
compounds RhHCl(SiR3){xant(PiPr2)2} (SiR3 = SiHPh2 (3),
SiEt3 (4)) and IrHCl(SiR3){xant(PiPr2)2} (SiR3 = SiHPh2 (5), SiEt3 (6)). Complexes 3 and 5 undergo a Cl/H position exchange
process via the MH{xant(PiPr2)2} (M = Rh (8), Ir (E)) intermediates. The rhodium complex 3 affords the square planar d8-silyl
derivative Rh(SiClPh2){xant(PiPr2)2} (7), whereas the iridium derivative 5 gives IrH2(SiClPh2){xant(PiPr2)2} (9), which is
stable. In agreement with the formation of 7, the reactions of 8 with silanes are a general method to prepare square planar d8-
rhodium-silyl derivatives. Thus, the addition of triethylsilane and triphenylsilane to 8 initially leads to the dihydrides
RhH2(SiR3){xant(PiPr2)2} (SiR3 = SiEt3 (10), SiPh3 (11)), which lose molecular hydrogen to afford Rh(SiR3){xant(PiPr2)2}
(SiR3 = SiEt3 (12), SiPh3 (13)). Treatment of 7 with NaBArF ·2H2O leads to the cationic five-coordinate d6-species
4
[RhH{Si(OH)Ph2}{xant(PiPr2)2}]BArF4 (14) through a silylene intermediate. According to the participation of the latter in the
formation of 14, this cation is an efficient catalyst precursor for the monoalcoholysis of diphenylsilane with a wide range of
alcohols, reaching turnover frequencies at 50% of conversion between 4000 and 76 500 h−1. The X-ray structures of 3, 6, 7, 9, 12,
and 14 are also reported.
Scheme 1
INTRODUCTION
■
Complexes containing diphosphine pincer ligands are attracting
increased interest because their high stability and disposition of
the donor atoms allow them to develop a marked ability to
form less common coordination polyhedra and favor unusual
metal oxidation states.1 Thus, in the search for new transition-
metal catalysts, more robust than those based on trans-
M(PiPr3)2 metal fragments, we synthesized the ligands 9,9-
dimethyl-4,5-bis(diisopropylphosphino)xanthene (xant-
(PiPr2)2) and 4,6-bis(diisopropylphosphino)dibenzofuran (dbf-
(PiPr2)2) three years ago.2 These diphosphines were sub-
sequently used to prepare POP-complexes of Os(II), Os(III),
Os(IV), and Os(VI), some of which proved to be promising
alternatives to ruthenium for the direct synthesis of imines from
alcohols and amines, with liberation of molecular hydrogen,3
and for the regioselective head-to-head (Z)-dimerization of
terminal alkynes.4 We have recently widened our work to
rhodium and iridium. Thus, following the previously developed
methodology to access the chemistry of the trans-Rh(PiPr3)2
and trans-Ir(PiPr3)2 metal fragments, we performed the
reactions of the dimers [M(μ-Cl)(C8H14)2]2 (M = Rh, Ir)
with xant(PiPr2)2 that afforded the square planar rhodium(I)
derivative RhCl{xant(PiPr2)2} (1)5 and the iridium(III)
the hydrosilylation of unsaturated organic substrates,8 the direct
synthesis of chlorosilanes,9 and Si−H/OH coupling.10 Silyl
complexes containing pincer diphosphine ligands are very rare,
in particular for rhodium and iridium. The linker groups
encountered consist of either metalated aryl or amide units in
anionic POCOP or PNP ligands or neutral PP2 triphosphines
(Chart 1). Brookhart11 has studied the mechanism of
(POCOP)IrH2-catalyzed reduction of a variety of tertiary
complex IrHCl{xant(PiPr2)[iPrPCH(Me)CH2]} (2) in high
yields (Scheme 1).6 Now, we have investigated the reactivity of
1 and 2 toward silanes.
Reactions of transition-metal complexes with silanes are of
great current interest due to the relevance of M-SiR3
intermediates7 in transition-metal catalyzed processes such as
Received: July 26, 2013
Published: October 2, 2013
© 2013 American Chemical Society
12108
dx.doi.org/10.1021/ic401931y | Inorg. Chem. 2013, 52, 12108−12119

Inorganic Chemistry
Article
Complex 3 was characterized by X-ray diffraction analysis.
Figure 1 gives a view of its structure. As expected for a pincer
Chart 1
Figure 1. ORTEP diagram of complex 3 (50% probability ellipsoids).
Hydrogen atoms (except hydride and Si−H) are omitted for clarity.
Selected bond lengths (Å) and angles (deg): Rh−Cl = 2.4367(9), Rh−
P(1) = 2.2885(9), Rh−P(2) = 2.3046(9), Rh−Si(1) = 2.2660(10),
Rh−O(1) = 2.384(2); P(1)−Rh−P(2) = 160.27(3), P(1)−Rh−O(1)
= 80.83(6), P(2)−Rh−O(1) = 79.58(6), Si(1)−Rh−O(1) =
158.32(6).
amides with H2SiEt2 (POCOP = 2,6-bis(di-tert-
butylphophinito)phenyl) and established that the neutral silyl
trihydride Ir(V) complex (POCOP)IrH3(SiHEt2) is the
catalytically active species, whereas the highly electrophilic η1-
silane derivative [(POCOP)IrH(η1-HSiEt3)]+ catalyzes the
hydrosilylation of ketones, aldehydes, esters, epoxides, allyl
halides, and ethers. Tilley12 has described synthetic pathways to
a variety of (PNP)Ir−silyl and −silylene complexes (PNP =
bis(o-diisopropylphosphinophenyl)amide) and explored the
catalytic activation of the silylene species in the silane
alcoholysis and aminolysis and for the hydrosilylation of
ketones and alkenes. Ozerov13 has provided insight into the
relative thermodynamic affinity of the (PNP)Rh skeleton
toward the oxidative addition of various halosilanes and how it
compares with its affinity toward addition of other species.
Milstein14 has reported on the synthesis of rhodium and
coordination of the diphosphine, the Rh(POP) skeleton is T-
shaped with the rhodium atom situated in the common vertex
and P(1)−Rh−P(2), P(1)−Rh−O(1), and P(2)−Rh−O(1)
angles of 160.27(3)°, 80.83(6)°, and 79.58(6)°, respectively.
So, the coordination geometry around the metal center can be
rationalized as a distorted octahedron with the silyl group trans-
disposed to the oxygen atom of the diphosphine (Si(1)−Rh−
O(1) = 158.32(6)°) and the hydride trans-disposed to the
chloride ligand. This ligand disposition is consistent with a
concerted cis-addition of the Si−H bond along the O−Rh−Cl
axis of 1 with the silyl group directed toward the chloride
ligand.15 The Rh−Si bond length of 2.2660(10) Å compares
well with Rh(III)−Si single bond distances previously
reported.16
i
iridium complexes containing the triphosphine ligand Pr2P-
(CH2)3P(Ph)(CH2)3PiPr2 (PP2) and described their reactivity
toward HSi(SEt)3.
This paper reports on the similarities and differences in the
behavior of the metal fragments Rh{xant(PiPr2)2} and
Ir{xant(PiPr2)2} toward silanes and on the catalytic activity of
the five-coordinate d6-complex [RhH{Si(OH)Ph2}{xant-
1
The H, 31P{1H}, and 29Si{1H} NMR spectra of 3 and 4, in
benzene-d6, at room temperature are consistent with the
(PiPr2)2}]BArF in the monoalcoholysis of diphenylsilane.
1
4
structure shown in Figure 1. Thus, the H NMR spectra show
hydride resonances at −15.90 (3) and −16.29 (4) ppm which
appear as double triplets with H−Rh and H−P coupling
constants of about 24 and 15 Hz, respectively. In agreement
with equivalent PiPr2 groups, the 31P{1H} NMR spectra contain
at 42.9 (3) and 41.6 (4) ppm doublets with P−Rh coupling
constants of 112 and 120 Hz, respectively. In the 29Si{1H}
NMR spectra, the silyl groups display at 4.1 (3) and 40.3 (4)
ppm double triplets with Si−Rh and Si−P coupling constants
of 36 and 13 Hz (3) and 32 and 11 Hz (4).
Iridium is more reducing than rhodium and shows higher
tendency to form coordinatively saturated compounds.6,17 As a
consequence, the iridium dimer [Ir(μ-Cl)(C8H14)2]2 reacts
with xant(PiPr2)2 to afford the saturated d6 complex 2 (Scheme
1). However, the latter undergoes demetalation by reductive
elimination to act as a synthon of the unsaturated d8 species
IrCl{xant(PiPr2)2} (A),6 the iridium(I) counterpart of 1. Thus,
at room temperature, the treatment of toluene solutions of 2
with 1.1 equiv of diphenylsilane and triethylsilane affords
IrHCl(SiR3){xant(PiPr2)2} (SiR3 = SiHPh2 (5), SiEt3 (6)), the
RESULTS AND DISCUSSION
■
Saturated d6-Hydride-silyl Complexes. The square
planar rhodium(I) complex RhCl{xant(PiPr2)2} (1) oxidatively
adds the Si−H bond of silanes. Thus, at room temperature, the
treatment of toluene solutions of this compound with 1.1 equiv
of diphenylsilane and triethylsilane leads to the saturated d6-
hydride-silyl derivatives RhHCl(SiR3){xant(PiPr2)2} (SiR3
=
SiHPh2 (3), SiEt3 (4)), which were isolated as white solids in
81% (3) and 56% (4) yield, according to eq 1.
12109
dx.doi.org/10.1021/ic401931y | Inorg. Chem. 2013, 52, 12108−12119

Inorganic Chemistry
Article
iridium counterparts of 3 and 4, which were isolated as white
solids in 41% (5) and 68% (6) yield, according to Scheme 2.
hydrogen to give the rhodium(I) derivative Rh(SiClPh2){xant-
(PiPr2)2} (7), which contains a chlorodiphenylsilyl group
resulting from an additional migration of the chloride ligand
from the metal center to the silicon atom. Under these
conditions, the reaction is quantitative after 5 days, as judged by
1H and 31P{1H} NMR spectroscopy.
Scheme 2
Complex 7 was isolated as red crystals in 95% yield and
characterized by X-ray diffraction analysis. Figure 3 shows a
Complex 6 was characterized by X-ray diffraction analysis.
Figure 2 gives a view of its structure. Like for 3 the M(POP)
Figure 3. ORTEP diagram of complex 7 (50% probability ellipsoids).
Hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and
angles (deg): Rh−P(1) = 2.2664(8), Rh−P(2) = 2.2728(7), Rh−Si =
2.2581(8), Rh−O = 2.2609(18); P(1)−Rh−P(2) = 161.97(3), P(1)−
Rh−O = 81.25(5), P(2)−Rh-O = 81.19(5), Si−Rh−O = 179.35(6).
view of its structure. The coordination geometry around the
rhodium atom is almost square planar19 with the diphosphine
coordinated in the expected pincer fashion (P(1)−Rh−P(2) =
161.97(3)°, P(1)−Rh−O = 81.25(5)°, P(2)−Rh−O =
81.19(5)°) and the silyl group trans disposed to the oxygen
atom of the diphosphine (Si−Rh−O = 179.35(6)°). The
greatest deviation from the best plane through the rhodium,
silicon, P(1), oxygen, and P(2) atoms is 0.0506(4) Å for Rh.
The Rh−Si bond length of 2.2581(8) Å compares well with
those reported for the few Rh(I)-silyl complexes characterized
by X-ray diffraction analysis.19,20 In agreement with the high
Figure 2. ORTEP diagram of complex 6 (50% probability ellipsoids).
Hydrogen atoms (except hydride) are omitted for clarity. Selected
bond lengths (Å) and angles (deg): Ir−Cl = 2.4733(12), Ir−P(1) =
2.3012(12), Ir−P(2) = 2.2968(12), Ir−Si = 2.3402(14), Ir−O
2.374(3); P(1)−Ir−P(2) = 155.00(4), P(1)−Ir−O = 80.19(8),
P(2)−Ir−O = 77.45(9), Si−Ir−O = 179.66(9).
skeleton is T-shaped with the iridium atom situated in the
common vertex and P(1)−Ir−P(2), P(1)−Ir−O, and P(2)−
Ir−O angles of 155.00(4)°, 80.19(8)°, and 77.45(9)°,
respectively. Thus, the octahedral coordination polyhedron
around the metal center is as that of the rhodium analogue,
with the silyl group trans to the oxygen atom of the
diphosphine (Si−Ir−O = 179.66(9)°), whereas the hydride
lies trans to the chloride ligand. The Ir−Si bond length of
2.3402(14) Å agrees well with those reported for other Ir(III)-
SiR3 derivatives.18
1
symmetry of the molecule, the H and 13C{1H} NMR spectra
show two signals for the methyl groups of the phosphine
isopropyl substituents (δ1 , 1.19 and 1.01; δ13C, 20.3 and 17.9)
H
and a signal for the methyl substituents of the central
heterocycle (δ1 , 1.24; δ13C, 31.0), whereas the 31P{1H}
H
NMR spectrum contains at 49.4 ppm a doublet with a P−Rh
coupling constant of 153.1 Hz. The silyl group displays at 49.2
ppm a double triplet with Si−Rh and Si−P coupling constants
of 82 and 22 Hz, respectively, in the 29Si{1H} NMR spectrum.
The formation of 7 could be rationalized according to
pathways a and b of Scheme 3. The reductive elimination of
HSiClPh2 from 3 should initially afford the previously described
square planar rhodium(I) derivative RhH{xant(PiPr2)2} (8).6
The oxidative addition of the H−Si bond of HSiClPh2 along
the O−Rh−H axis of 8 with the silyl group directed toward the
oxygen atom of the diphosphine should lead to the cis-
dihydride intermediate B (pathway a), while the same addition
with the silyl group on the hydride ligand should afford the
trans-dihydride intermediate C (pathway b). The reductive
elimination of molecular hydrogen from B would be a fast
1
The H, 31P{1H}, and 29Si{1H} NMR spectra of 5 and 6, in
benzene-d6, at room temperature are consistent with those of 3
and 4 and with the structure shown in Figure 2. The presence
of a hydride ligand in these compounds is strongly supported
1
by the H NMR spectra, which contain at −19.91 (5) and
−20.06 (6) ppm triplets with H−P coupling constants of 14.5
and 16.0 Hz, respectively. As expected for equivalent PiPr2
groups, the 31P{1H} NMR spectra show singlets at 29.9 (5) and
29.0 (6) ppm. The silyl groups display at −36.3 (5) and −7.6
(6) ppm triplets with Si−P coupling constants of 10 and 8 Hz,
respectively, in the 29Si{1H} NMR spectra.
Cl/H Position Exchange. The diphenylsilyl complex 3 is
unstable in solution. In toluene at 50 °C, it releases molecular
12110
dx.doi.org/10.1021/ic401931y | Inorg. Chem. 2013, 52, 12108−12119

Inorganic Chemistry
Article
Scheme 3
reaction given the cis-orientation of the hydride ligands and the
marked preference of the Rh{xant(PiPr2)2} skeleton for the
unsaturated d8 species. However, the trans-disposition of the
hydride ligands in C prevents the three-centered transition state
for their reductive elimination. So, the loss of molecular
hydrogen requires the previous dissociation of the oxygen atom
of the diphosphine, which should became bidentate.21 The
dissociation of the oxygen atom of the diphosphine should
allow the formation of the dihydrogen intermediate or
transition state D, which could easily give 7.
Scheme 4
Complex 5, the iridium counterpart of 3, is also unstable in
solution. In toluene at 50 °C, it evolves into the trans-dihydride
IrH2(SiClPh2){xant(PiPr2)2} (9) that is the iridium counterpart
of intermediate C (Scheme 3). The transformation is
1
quantitative after 2 days, as judged by H and 31P{1H} NMR
spectroscopy. The formation of 9 can be rationalized in a
similar manner to that of C via a square planar iridium(I)
monohydride intermediate IrH{xant(PiPr2)2} (E), analogous to
8, which should be generated by reductive elimination of
HSiClPh2. Thus, the subsequent oxidative addition of the H−Si
bond of the formed silane along the O−Ir−H axis of E with the
silyl group directed toward the hydride ligand could afford the
trans-dihydride (Scheme 4). In favor of this proposal, we have
observed that the addition of 2.0 equiv of diphenylsilane to a
benzene-d6 solution of 6 in an NMR tube at 50 °C affords 9, via
5, and HSiEt3. In this context, it should be noted that complex
9 is more stable than 5 in spite of the destabilization produced
by the strong trans influence of the hydride ligands mutually
trans disposed.22 This fact is consistent with density functional
theory (DFT) calculations on the model complexes Os(SiR3)-
Cl(CO)(PH3)2 (R = F, Cl, OH, Me), which have revealed that
a linear combination of Si-R σ* orbitals is responsible for some
π-acceptor capacity of the silyl group. This component
increases its contribution to the bond as the electronegativity
of the substituent at the silicon atom also increases.23 The
difference in behavior between rhodium and iridium in this Cl/
H position exchange process agrees well with the higher
preference of iridium for the saturated d6 species.6,17
atom can be rationalized as a distorted octahedron with the
diphosphine mer-coordinated (P(1)−Ir−P(2) = 159.01(4)°,
P(1)−Ir−O = 81.04(7)°, P(2)−Ir−O = 80.77(7)°) and the
silyl group trans disposed to the oxygen atom of the
diphosphine (Si−Ir−O = 167.72(7)°). The Ir−Si bond length
of 2.2655(11) Å compares well with that of 6.
1
The H, 31P{1H}, and 29Si{1H} NMR spectra in benzene-d6,
at room temperature, are consistent with the structure shown in
Figure 4. In agreement with the presence of trans-hydrides, the
1H NMR spectrum shows at −4.90 ppm a triplet with a H−P
coupling constant of 16.6 Hz. As expected for equivalent PiPr2
groups, the 31P{1H} NMR spectrum contains at 47.9 ppm a
singlet. The silyl group displays at −4.8 ppm a triplet with a Si−
P coupling constant of 20 Hz in the 29Si{1H} NMR spectrum.
Square-Planar Rhodium(I)-silyl Complexes. The for-
mation of 7 according to Scheme 3 suggested that the
monohydride 8 should be an efficient starting material to
prepare square planar rhodium(I)-silyl derivatives in a general
manner. The addition of 1.1 equiv of triethylsilane and
The trans-dihydride 9 was isolated as a white solid in 60%
yield and characterized by X-ray diffraction analysis. An
ORTEP drawing of the molecule is shown in Figure 4. The
structure proves the Cl/H position exchange and the trans
disposition of the hydride ligands (H(01)−Ir−H(02) =
173(3)°). The coordination polyhedron around the iridium
12111
dx.doi.org/10.1021/ic401931y | Inorg. Chem. 2013, 52, 12108−12119

Inorganic Chemistry
Article
Figure 4. ORTEP diagram of complex 9 (50% probability ellipsoids).
Hydrogen atoms (except hydrides) are omitted for clarity. Selected
bond lengths (Å) and angles (deg): Ir−P(1) = 2.2811(10), Ir−P(2) =
2.2704(10), Ir−Si = 2.2654(11); P(1)−Ir−P(2) = 159.01(4), P(1)−
Ir−O = 81.04(7), P(2)−Ir−O = 80.77(7), Si−Ir−O = 167.72(7),
H(01)−Ir−H(02) = 173(3).
Figure 5. ORTEP diagram of complex 12 (50% probability ellipsoids).
Hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and
angles (deg): Rh−P(1) = 2.2541(8), Rh−P(2) = 2.2573(8), Rh−Si =
2.3090(8), Rh−O = 2.3149(18); P(1)−Rh−P(2) = 158.51(3), P(1)−
Rh-O = 81.39(5), P(2)−Rh−O = 81.57(5), Si−Rh−O = 170.0(5).
triphenylsilane to the toluene solutions of 8 leads to the trans-
dihydride derivatives RhH2(SiR3){xant(PiPr2)2} (SiR3 = SiEt3
(10), SiPh3 (11)), which release molecular hydrogen to afford
square planar with the diphosphine coordinated in a mer-
fashion (P(1)−Rh−(2) = 158.51(3)°, P(1)−Rh−O =
81.39(5)°, P(2)−Rh−O = 81.57(5)°) and the silyl group
trans disposed to the oxygen atom of the diphosphine (Si−Rh−
O = 170.0(5)°). In this case, the greatest deviation from the
best plane through the rhodium, silicon, P(1), oxygen, and P(2)
atoms is 0.1198(4) Å for Rh. The Rh−Si bond length of
2.3090(8) Å compares well with that of 7. In agreement with
Figure 5, the 31P{1H} NMR spectra of 12 and 13 contain at
46.0 and 44.7 ppm doublets with P−Rh coupling constants of
171 and 159 Hz, respectively, whereas the 29Si{1H} NMR
spectra show at 25.0 (12) and 14.4 (13) ppm double triplets
with Si−Rh and Si−P coupling constants of 54 and 19 (12) Hz
and 66 and 21 (13) Hz.
the rhodium(I) complexes Rh(SiR3){xant(PiPr2)2} (SiR3
=
SiEt3 (12), SiPh3 (13)). The reductive elimination of molecular
hydrogen could take place in a similar manner to those shown
in Scheme 3 or via a protonation−dehydrogenation mecha-
nism, as reported by Brookhart for a related PNP-Ir system,24
catalyzed by traces of H2O. The trend of 10 and 11 to lose
molecular hydrogen is in contrast with the behavior of 4 and
RhH2Cl{xant(PiPr2)2} and consistent with the inertness of the
monohydride 8 toward molecular hydrogen.6
Scheme 5
Catalytic Monoalcoholysis of Ph2SiH2. The square
planar rhodium(I) complex 7 is the entry to an interesting
rhodium(III)-silylol species. Treatment of its fluorobenzene
solutions with 1.2 equiv of NaBArF ·2H2O (ArF = 3,5-
4
bis(trifluoromethyl)phenyl), at room temperature, for 1 h
results in chloride abstraction from the silyl group and the
formation of the five-coordinate hydride-silylol derivative
The dihydride intermediates 10 and 11 were spectroscopi-
[RhH{Si(OH)Ph2}{xant(PiPr2)2}]BArF (14). Its formation
4
cally detected and fully characterized when the reactions were
performed in a NMR tube at 258 K. Their H NMR spectra
can be rationalized according to Scheme 6. The chloride
abstraction should initially afford the silylene intermediate F,
which could subsequently undergo the heterolytic addition of
an O−H bond of water to give the hydride-silylol derivative.
Complex 14 was isolated as a white solid in 76% yield and
characterized by X-ray diffraction analysis. The structure proves
its formation. Figure 6 shows a view of the cation of the salt.
The geometry around the rhodium atom can be described as a
distorted trigonal bipyramid with the PiPr2 groups of the pincer
in apical positions (P(1)−Rh−P(2) = 157.16(3)°, P(1)−Rh−
O(1) = 83.47(5)°, P(2)−Rh−O(1) = 84.13(5)°) and
inequivalent angles within the Y-shaped equatorial plane
(O(1)−Rh−Si = 138.62(5)°, O(1)−Rh−H(01) =
156.0(12)°, and Si−Rh−H(01) = 65.3(12)°). The Rh−Si
bond length of 2.3000(8) Å is about 0.03 Å longer than that of
the saturated rhodium(III) derivative 3. In agreement with the
1
show at −5.63 (10) and −5.02 (11) ppm double triplets, with
H−Rh and H−P coupling constants of 17.6 and 18.0 (10) Hz
and 19.3 and 16.1 (11) Hz, corresponding to the hydride
ligands. The 31P{1H} NMR spectra contain at 61.6 (10) and
59.3 (11) ppm doublets with Rh−P coupling constants of 126
and 120 Hz, respectively. The silyl groups display at 33.0 (10)
and 9.4 (11) ppm double triplets, with Si−Rh and Si−P
coupling constants of 33 and 9 (10) Hz and 42 and 12 (11)
Hz, in the 29Si{1H} NMR spectra.
The square planar complexes 12 and 13 were isolated as red
solids in a 58% and 81% yield, respectively. The triethylsilyl
derivative 12 was characterized by X-ray diffraction analysis.
Figure 5 shows an ORTEP drawing of the molecule. Like for 7,
the coordination geometry around the rhodium atom is almost
12112
dx.doi.org/10.1021/ic401931y | Inorg. Chem. 2013, 52, 12108−12119

Inorganic Chemistry
Article
Tilley has demonstrated that iridium-silylene complexes are
active catalyst for the alcoholysis of silanes.12c This prompted
us to investigate the alcoholysis of the diphenylsilane promoted
by 14 (eq 2), since its formation seems to take place through
the silylene intermediate F. The reactions were performed in
toluene at 32 °C, using 0.17 mol % of catalyst and silane and
alcohol concentrations of 0.3 M. Under these conditions,
alkoxysilanes HSi(OR)Ph2 were selectively formed in quanti-
tative yield, after seconds or a few minutes, with spectacularly
high turnover frequencies at 50% conversion (TOF50%), which
range from 4000 to 76 500 h−1, and isolated in high yields
between 71% and 92% (Table 1).
Scheme 6
0.17 mol% 14
H2SiPh2 + ROH ⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯→ HSi(OR)Ph2 + H2
(2)
toluene, 32°C
Table 1. Monoalcoholysis of H2SiPh2 Catalyzed by
a
[RhH{Si(OH)Ph2}{xant(PiPr2)2}]BArF (14)
4
Figure 6. ORTEP diagram of the cation of complex 14 (50%
probability ellipsoids). Hydrogen atoms (except hydride and O−H)
are omitted for clarity. Selected bond lengths (Å) and angles (deg):
Rh−P(1) = 2.3165(7), Rh−P(2) = 2.2794(7), Rh−Si = 2.3000(8),
Rh−O(1) = 2.1859(17); P(1)−Rh−P(2) = 157.16(3), P(1)−Rh−
O(1) = 83.47(5), P(2)−Rh−O(1) = 84.13(5), O(1)−Rh−Si =
138.62(5), Si−Rh−H(01) = 65.3(12), O(1)−Rh−H(01) = 156.0(12).
a
0.17 mol % 14, 0.3 M H2SiPh2, 0.3 M alcohol in toluene (5 mL) at 32
°C. Turnover frequencies [(mol product/mol Rh)/time] were
calculated at 50% conversion.
Primary, secondary, and tertiary alcohols, as well as phenol
were successfully used. For primary alcohols, the reaction rates
increase as the length of the carbon chain increases, that is, in
the sequence methanol (run 1) < ethanol (run 2) < 1-butanol
(run 3) < 1-octanol (run 4). The secondary alcohols 2-
propanol (run 6) and cyclohexanol (run 7) yield the
corresponding alkoxysilanes with TOF50% values similar or
higher than 1-octanol. Although the reactions with the tertiary
t-butanol (run 8) and with phenol (run 9) are also very
efficient, these substrates afford the lowest TOF50% values, 18
000 h−1 and 4000 h−1, respectively.
1
presence of the hydride ligand, the H NMR spectrum, in
dichloromethane-d2, at 233 K shows at −17.43 ppm a double
triplet with H−Rh and H−P coupling constants of 39.4 and
12.5 Hz, respectively, whereas the OH- resonance appears at
3.25 ppm as a broad singlet. As expected for equivalent PiPr2
groups coordinated to a Rh(III) center, the 31P{1H} NMR
spectrum at 233 K contains at 52.1 ppm a doublet with a P−Rh
coupling constant of 119 Hz. The silylol group displays at 26.1
ppm a double triplet with Si−Rh and Si−P coupling constants
of 32 and 7 Hz, respectively, in the 29Si{1H} NMR spectrum at
233 K.
The selective monoalcoholysis of the silane is notable and
fully consistent with the participation of a silylene species as key
12113
dx.doi.org/10.1021/ic401931y | Inorg. Chem. 2013, 52, 12108−12119

Inorganic Chemistry
Article
SiClR2 oxidative addition to MH{xant(PiPr2)2} intermediates.
According to the higher oxidizing character of the 4d metals,
the rhodium species lose molecular hydrogen and, as a
consequence, the addition of the H−Si bond of silanes to the
square planar monohydride complex RhH{xant(PiPr2)2} leads
to square planar d8-silyl compounds Rh(SiR3){xant(PiPr2)2}, in
a general manner, through the corresponding d6 intermediates
MH2(SiR3){xant(PiPr2)2}. Interestingly, the abstraction of
chloride from Rh(SiClPh2){xant(PiPr2)2} in the presence of
water yields the five-coordinate d6-species [RhH{Si(OH)Ph2}-
{xant(PiPr2)2}]+, as a result of the addition of an O−H bond of
water to the Rh−Si double bond of a silylene intermediate. In
agreement with the participation of the latter in the formation
of this cationic compound, it is a very efficient catalyst
precursor for the selective monoalcoholysis of diphenylsilane
that reaches turnover frequencies (TOF) at 50% of conversion
up to 76 500 h−1.
Scheme 7
In conclusion, the Rh{xant(PiPr2)2} metal fragment favors
unsaturated d8-square planar, Rh(SiR3){xant(PiPr2)2}, and d6-
five coordinate, [RhH{Si(OH)Ph2}{xant(PiPr2)2}]+, silyl com-
plexes whereas the Ir{xant(PiPr2)2} metal fragment stabilizes
saturated d6-silyl derivatives, IrHCl(SiR3){xant(PiPr2)2} and
IrH2(SiR3){xant(PiPr2)2}. The stabilization of saturated d6-
Rh{xant(PiPr2)2} species seems to need the presence of a
coordinated π-donor ligand such as chloride.
EXPERIMENTAL SECTION
■
General Information. All reactions were carried out with rigorous
exclusion of air using Schlenk-tube techniques. Solvents (except
fluorobenzene that was dried and distilled under argon) were obtained
oxygen- and water-free from an MBraun solvent purification apparatus.
The alcohols used in the catalytic reactions were dried by standard
procedures and distilled under argon prior to use. 1H, 13C{1H},
31P{1H}, and 29Si{1H} NMR spectra were recorded on Bruker 300
ARX, Bruker Avance 300 MHz and Bruker Avance 400 MHz
instruments. Chemical shifts (expressed in parts per million) are
referenced to residual solvent peaks (1H, 13C{1H}), external 85%
H3PO4 (31P{1H}), or external SiMe4 (29Si{1H}). Coupling constants J
and N are given in hertz. Attenuated total reflection infrared spectra
(ATR-IR) of solid samples were run on a Perkin-Elmer Spectrum 100
FT-IR spectrometer. C, H, and N analyses were carried out in a
Perkin-Elmer 2400 CHNS/O analyzer. High-resolution electrospray
mass spectra were acquired using a MicroTOF-Q hybrid quadrupole
time-of-flight spectrometer (Bruker Daltonics, Bremen, Germany).
intermediate of the process. The nucleophilic attack of the
alcohol to an η2-silane complex, M(η2-H-SiR3), has been
considered an alternative manner of generating silylethers.25
However, such possibility cannot justify the selectivity observed
in this case. Furthermore, it should imply the heterolytic
cleavage of the H−Si bond, which should require an
electrophilic metal center, and this does not seem to be the
case of Rh(I).26 It should be also noted that in contrast to
standard methods involving the treatment of silylchloride with
an alcohol in the presence of a base that generates
hydrochloride salts byproducts,27 this process is environ-
mentally benign and occurs with liberation of molecular
hydrogen.
The catalysis can be rationalized according to Scheme 7. The
reductive elimination of HSi(OH)Ph2 from 14 could initially
afford the rhodium(I) intermediate G, which should oxidatively
add diphenylsilane to give H. Thus, the elimination of
molecular hydrogen from the latter through I could lead to
the silylene F, which should form J in a similar manner as 14.
Then, the reductive elimination of the alkoxysilane from J could
generate G again.
Xant(PiPr2)2,2 IrHCl{xant(PiPr2)[iPrPCH(Me)CH2]} (2),6 RhCl-
{xant(PiPr2)2} (1),6 RhH{xant(PiPr2)2} (8),6 and NaBArF ·2H2O28
4
were prepared by published methods.
Reaction of RhCl{xant(PiPr2)2} (1) with H2SiPh2: Preparation
of RhHCl(SiHPh2){xant(PiPr2)2} (3). Diphenylsilane (109 μL, 0.57
mmol) was added to a solution of 1 (300 mg, 0.52 mmol) in toluene
(3 mL). After the resulting solution was stirred for 10 min at room
temperature, it was evaporated to dryness to afford a white residue.
Addition of pentane afforded a white solid that was washed with
pentane (2 × 3 mL) and dried in vacuo. Yield: 320.0 mg (81%). Anal.
Calcd. for C39H52ClOP2RhSi: C, 61.21; H, 6.85. Found: C, 60.75; H,
6.72. HRMS (electrospray, m/z): calcd. for C39H52OP2RhSi [M −
Cl]+: 729.2312; found: 729.2352. IR (neat compound, cm−1): ν(Rh−
CONCLUDING REMARKS
■
This study has revealed that the square planar d8-complexes
MCl{xant(PiPr2)2} (M = Rh, Ir) oxidatively add the Si−H
bond of tertiary and secondary silanes, along the O−M−Cl axis
with the silyl group directed toward the chloride ligand, to give
d6-chloro-hydride-silyl derivatives MHCl(SiR3){xant(PiPr2)2}
and MHCl(SiHR2){xant(PiPr2)2}. Complexes containing sec-
ondary silyl groups undergo a Cl/H position exchange to afford
dihydride-chlorosilyl compounds MH2(SiClR2){xant(PiPr2)2},
through Cl-SiHR2 reductive elimination and subsequent H-
1
H) 2097 (w); ν(Si−H) 2054 (m); ν(C−O−C) 1093 (m). H NMR
(400.13 MHz, C6D6, 293 K, δ): 8.35 (d, JH−H = 7.4, 4H, CH SiHPh2),
7.33 (t, JH−H = 7.4, 4H, CH SiHPh2), 7.21 (t, JH−H = 7.4, 2H, CH
SiHPh2), 7.13 (d, JH−H = 7.6, 2H, CH-arom), 7.07 (m, 2H, CH-arom),
6.88 (t, JH−H = 7.6, 2H, CH-arom), 6.13 (t, JH−P = 11.2, 1H, Si−H),
2.40 (m, 2H, PCH(CH3)2), 1.96 (m, 2H, PCH(CH3)2), 1.51 (dvt,
JH−H = 7.2, N = 14.4, 6H, PCH(CH3)2), 1.32 (s, 3H, CH3), 1.24 (dvt,
JH−H = 7.9, N = 16.4, 6H, PCH(CH3)2), 1.20 (s, 3H, CH3), 1.11 (dvt,
JH−H = 7.6, N = 15.8, 6H, PCH(CH3)2), 0.78 (dvt, JH−H = 6.5, N =
12114
dx.doi.org/10.1021/ic401931y | Inorg. Chem. 2013, 52, 12108−12119

Inorganic Chemistry
Article
12.9, 6H, PCH(CH3)2), −15.90 (dt, JH−Rh = 24.5, JH−P = 14.2, 1H,
Rh−H). 13C{1H} NMR (100.61 MHz, C6D6, 293 K, δ): 154.1 (vt, N =
11.1, C-arom), 142.9 (t, JC−P = 1.5, C-arom, SiHPh2), 137.2 (s, CH-
arom SiHPh2), 132.2 (vt, N = 5.0, C-arom), 131.1 (s, CH-arom
SiHPh2), 128.3 (s, CH-arom), 128.0 (s, CH-arom), 127.4 (s, CH-arom
SiHPh2), 124.0 (vt, N = 5.2, CH-arom), 123.1 (vt, N = 26.5, C-arom),
34.6 (s, C(CH3)2), 34.0, 28.7 (both s, C(CH3)2), 27.1 (vt, N = 22.5,
PCH(CH3)2), 26.6 (dvt, JC−Rh = 2.3, N = 26.7, PCH(CH3)2), 22.5 (s,
PCH(CH3)2), 19.6 (s, PCH(CH3)2), 19.3 (vt, N = 6.3, PCH(CH3)2),
17.0 (s, PCH(CH3)2). 31P{1H} NMR (161.98 MHz, C6D6, 293 K, δ):
42.9 (d, JP−Rh = 112). 29Si{1H} NMR (59.63 MHz, C6D6, 293 K, δ):
4.1 (dt, JSi−Rh = 36, JSi−P = 13).
resulting solution was stirred for 1 h at room temperature, it was
evaporated to dryness to afford a white residue. Addition of pentane
afforded a white solid that was washed with pentane (3 × 2 mL) and
dried in vacuo. Yield: 80 mg (68%). Anal. Calcd. for C33H56ClIrOP2Si:
C, 50.39; H, 7.18. Found: C, 50.13; H, 7.36. HRMS (electrospray, m/
z): calcd. for C33H56IrOP2Si [M − Cl]+ 751.3200; found: 751.3231. IR
(cm−1): ν(Ir−H) 2227 (w). 1H NMR (300.13 MHz, C6D6, 293 K, δ):
7.20 (m, 2H, CH-arom), 7.07 (dd, JH−H = 7.6, JH−H = 1.5, 2H, CH-
arom), 6.87 (t, JH−H = 7.6, 2H, CH-arom), 3.09 (m, 2H, PCH(CH3)2),
2.28 (m, 2H, PCH(CH3)2), 1.59 (dvt, JH−H = 7.3, N = 15.7, 6H,
PCH(CH3)2), 1.46−138 (m, 21H, 6H PCH(CH3)2 + 15H Si-
(CH2CH3)3), 1.25 (s, 3H, CH3), 1.21 (s, 3H, CH3), 1.19 (dvt, JH−H
=
Reaction of RhCl{xant(PiPr2)2} (1) with HSiEt3: Preparation of
RhHCl(SiEt3){xant(PiPr2)2} (4). Triethylsilane (42 μL, 0.25 mmol)
was added to a solution of 1 (134 mg, 0.23 mmol) in toluene (3 mL).
After the resulting solution was stirred for 1 h at room temperature, it
was evaporated to dryness to afford a white residue. Addition of
pentane afforded a white solid that was washed with pentane (2 × 1
mL) and dried in vacuo. Yield: 90.0 mg (56%). Anal. Calcd. for
C33H56ClOP2RhSi: C, 56.85; H, 8.10. Found: C, 56.80; H, 8.10.
HRMS (electrospray, m/z): calcd. for C33H56OP2RhSi [M − Cl]+:
661.2625; found: 661.2750. IR (cm−1): ν(Rh−H) 2094 (w). 1H NMR
(400.13 MHz, C6D6, 293 K, δ): 7.20 (m, 2H, CH-arom), 7.11 (d, JH−H
= 7.6, 2H, CH-arom), 6.89 (t, JH−H = 7.6, 2H, CH-arom), 2.86 (m, 2H,
PCH(CH3)2), 2.20 (m, 2H, PCH(CH3)2), 1.57 (dvt, JH−H = 7.4, N =
15.6, 6H, PCH(CH3)2), 1.45 (m, 6H PCH(CH3)2 + 6H Si-
(CH2CH3)3), 1.37 (t, JH−H = 6.8, 9H, Si(CH2CH3)3), 1.31 (s, 3H,
CH3), 1.20 (dvt, JH−H = 7.6, N = 16.8, 6H, PCH(CH3)2), 1.18 (s, 3H,
CH3), 0.85 (dvt, JH−H = 6.6, N = 13.0, 6H, PCH(CH3)2), −16.29 (dt,
JH−Rh = 23.9, JH−P = 15.7, 1H, Rh−H). 13C{1H} NMR (100.61 MHz,
C6D6, 293 K, δ): 154.4 (vt, N = 10.5, C-arom), 132.2 (vt, N = 4.2, C-
arom), 130.4 (s, CH-arom), 127.2 (s, CH-arom), 123.8 (s, CH-arom),
123.6 (vt, N = 27.2, C-arom), 34.6 (s, C(CH3)2), 32.7 (s, C(CH3)2),
28.0 (dvt, JC−Rh = 3.4, N = 26.0, PCH(CH3)2), 27.9 (s, C(CH3)2), 27.6
(vt, N = 19.6, PCH(CH3)2), 20.3 (vt, N = 4.4, PCH(CH3)2), 20.1,
20.0, 17.7 (all s, PCH(CH3)2), 14.6 (s, Si(CH2CH3)3), 10.1 (s,
Si(CH2CH3)3). 31P{1H} NMR (161.98 MHz, C6D6, 293 K, δ): 41.6
(d, JP−Rh = 120). 29Si{1H} NMR (59.63 MHz, C6D6, 293 K, δ): 40.3
(dt, JSi−Rh = 32, JSi−P = 11).
Reaction of 2 with H2SiPh2: Preparation of IrHCl(SiHPh2)-
{xant(PiPr2)2} (5). Diphenylsilane (37 μL, 0.20 mmol) was added to a
solution of 2 (123 mg, 0.18 mmol) in toluene (1 mL). After the
resulting solution was stirred for 2 h at room temperature, it was
evaporated to dryness to afford a yellowish residue. Addition of
pentane afforded a white solid that was washed with pentane (2 × 1
mL) and dried in vacuo. Yield: 65.0 mg (41%). Anal. Calcd. for
C39H52ClIrOP2Si: C, 54.82; H, 6.13. Found: C, 54.47; H, 5.98. HRMS
(electrospray, m/z): calcd. for C39H51ClOP2IrSi [M − H]+: 853.2490;
found: 853.2422. IR (cm−1): ν(Ir−H) 2223 (w); ν(Si−H) 2035 (w);
ν(C−O−C) 1093 (m). 1H NMR (300.08 MHz, C6D6, 293 K, δ): 8.32
(d, JH−H = 7.4, 4H, CH SiHPh2), 7.32 (t, JH−H = 7.4, 4H, CH SiHPh2),
7.19 (t, JH−H = 7.4, 2H, CH SiHPh2), 7.07 (m, 4H, CH-arom), 6.86 (t,
JH−H = 7.5, 2H, CH-arom), 6.02 (t, JH−P = 8.1, 1H, Si−H), 2.59 (m,
2H, PCH(CH3)2), 2.07 (m, 2H, PCH(CH3)2), 1.43 (dvt, JH−H = 7.0,
N = 14.3, 6H, PCH(CH3)2), 1.32 (dvt, JH−H = 7.9, N = 16.3, 6H,
7.4, N = 15.6, 6H, PCH(CH3)2), 0.84 (dvt, JH−H = 6.9, N = 13.8, 6H,
PCH(CH3)2), −20.06 (t, JH−P = 16.0, 1H, Ir−H). 13C{1H} NMR
(75.47 MHz, C6D6, 293 K, δ): 154.9 (vt, N = 9.0, C-arom), 132.5 (vt,
N = 4.8, C-arom), 130.6 (s, CH-arom), 127.5 (s, CH-arom), 125.6 (vt,
N = 33.9, C-arom), 124.4 (vt, N = 4.5, CH-arom), 34.5 (s, C(CH3)2),
31.3, 29.9 (both s, C(CH3)2), 28.8 (vt, N = 32.3, PCH(CH3)2), 28.3
(vt, N = 22.9, PCH(CH3)2), 20.5, 19.8, 19.7, 18.4 (all s, PCH(CH3)2),
13.2 (s, Si(CH2CH3)3), 10.4 (s, Si(CH2CH3)3). 31P{1H} NMR
(121.49 MHz, C6D6, 293 K, δ): 29.0 (s). 29Si{1H} NMR (59.63
MHz, C6D6, 293 K, δ): −7.6 (t, JSi−P = 8).
Preparation of Rh(SiClPh2){xant(PiPr2)2} (7). A Schlenk flask
provided with a Teflon closure was charged with a solution of 3 (300
mg, 0.39 mmol) in toluene (3 mL) under argon atmosphere. After
being stirred for 5 days at 50 °C (the reaction was periodically checked
by 1H and 31P{1H} NMR spectroscopy) the resulting red solution was
evaporated to dryness. Pentane was added to afford an orange solid,
which was washed with pentane (2 × 3 mL) and dried in vacuo. Yield:
284 mg (95%). Anal. Calcd. for C39H50ClOP2RhSi: C, 61.38; H, 6.60.
Found: C, 61.52; H, 6.55. HRMS (electrospray, m/z) calcd. for
C39H51ClOP2RhSi: [M + H]+: 763.1922; found: 763.1936. IR (cm−1):
ν(C−O−C) 1091 (w). 1H NMR (300.13 MHz, C6H6, 293 K, δ): 8.40
(d, JH−H = 7.3, 4H, CH SiClPh2), 7.33 (t, JH−H = 7.3, 4H, CH
SiClPh2), 7.22 (t, JH−H = 7.3, 2H, CH SiClPh2), 7.16 (m, 2H, CH-
arom), 7.08 (t, JH−H = 7.5, 2H, CH-arom), 6.87 (t, JH−H = 7.5, 2H,
CH-arom), 2.27 (m, 4H, PCH(CH3)2), 1.24 (s, 6H, CH3), 1.19 (dvt,
JH−H = 7.7, N = 15.4, 12H, PCH(CH3)2), 1.01 (dvt, JH−H = 7.2, N =
13.4, 12H, PCH(CH3)2). 13C{1H} NMR (75.46 MHz, C6D6, 293 K,
δ): 155.7 (vt, N = 13.6, C-arom), 149.1 (dt, JC−Rh = 4.3, JC−P = 1.6, C-
arom SiClPh2), 137.2 (s, CH-arom SiClPh2), 131.5 (vt, N = 5.4, C-
arom), 131.4 (s, CH-arom), 127.4 (s, CH-arom), 127.3 (s, CH-arom
SiClPh2), 126.8 (s, CH-arom SiClPh2), 124.5 (vt, N = 15.0, C-arom),
124.4 (vt, N = 4.0, CH-arom), 34.2 (s, C(CH3)2), 31.0 (s, C(CH3)2),
25.5 (dvt, JRh−C = 2.9, N = 21.2, PCH(CH3)2), 20.3 (vt, N = 8.1,
PCH(CH3)2), 17.9 (s, PCH(CH3)2). 31P{1H} NMR (121.49 MHz,
C6D6, 293 K, δ): 49.4 (d, JP−Rh = 153.1). 29Si{1H} NMR (59.63 MHz,
C6D6, 293 K, δ): 49.2 (dt, JSi−Rh = 82, JSi−P = 22).
Isomerization of IrHCl(SiHPh2){xant(PiPr2)2} (5) to
IrH2(SiClPh2){xant(PiPr2)2} (9). 5 (100 mg, 0.11 mmol) was dissolved
in toluene (3 mL) and heated at 50 °C for 48 h. After this time (the
reaction was periodically checked by 1H and 31P{1H} NMR
spectroscopy) the solution was evaporated to ca. 0.2 mL to afford a
white residue. Addition of pentane afforded a white solid that was
washed with pentane (1 × 1 mL) and dried in vacuo. Yield: 60 mg
(60%). Anal. Calcd. for C39H52ClIrOP2Si: C, 54.82; H, 6.13. Found: C,
54.85; H, 6.12. HRMS (electrospray, m/z): calcd. for C39H51ClIrOP2Si
[M − H]+: 853.2490; found: 853.2421. IR (cm−1): ν(Ir−H) 2035 (w);
ν(C−O−C) 1093 (m). 1H NMR (300.08 MHz, C6D6, 293 K, δ): 8.37
(d, JH−H = 7.0, 4H, CH SiClPh2), 7.29 (t, JH−H = 7.0, 4H, CH
SiClPh2), 7.18 (t, JH−H = 7.0, 2H, CH SiClPh2), 7.11 (m, 2H, CH-
PCH(CH3)2), 1.27 (s, 3H, CH3), 1.22 (s, 3H, CH3), 1.09 (dvt, JH−H
=
7.7, N = 16.2, 6H, PCH(CH3)2), 0.80 (dvt, JH−H = 6.7, N = 13.5, 6H,
PCH(CH3)2), −19.91 (t, JH−P = 14.5, 1H, Ir−H). 13C{1H} NMR
(75.46 MHz, C6D6, 293 K, δ): 154.5 (vt, N = 9.7, C-arom), 142.7 (s,
C-arom, SiHPh2), 137.2 (s, CH-arom SiHPh2), 132.1 (vt, N = 4.8, C-
arom), 131.4 (s, CH-arom SiHPh2), 128.0 (s, CH-arom), 127.4 (s,
CH-arom SiHPh2), 125.1 (vt, N = 32.6, C-arom), 124.5 (vt, N = 5.3,
CH-arom), 34.4 (s, C(CH3)2), 33.0, 30.8 (both s, C(CH3)2), 27.1 (vt,
N = 22.5, PCH(CH3)2), 26.6 (vt, N = 26.7, PCH(CH3)2), 20.4, 19.5,
19.3, 17.6 (all s, PCH(CH3)2). 31P{1H} NMR (121.49 MHz, C6D6,
293 K, δ): 29.9 (s). 29Si{1H} NMR (59.63 MHz, C6D6, 293 K, δ):
−36.3 (t, JSi−P = 10).
arom), 6.92 (dd, JH−H = 7.4, JH−H = 1.3, 2H, CH-arom), 6.86 (t, JH−H
=
7.4, 2H, CH-arom), 2.32 (m, 4H, PCH(CH3)2), 1.15 (dvt, JH−H = 7.3,
N = 15.8, 12H, PCH(CH3)2), 1.13 (s, 6H, CH3), 1.08 (dvt, JH−H = 6.8,
N = 14.2, 12H, PCH(CH3)2), −4.90 (t, JH−P = 16.6, 2H, Ir−H).
13C{1H} NMR (75.46 MHz, C6D6, 293 K, δ): 156.9 (vt, N = 10.4, C-
arom), 145.1 (s, C-arom SiClPh2), 137.3 (s, CH-arom SiClPh2), 132.4
(vt, N = 5.1, C-arom), 130.1 (s, CH-arom SiClPh2), 128.2 (s, CH-
arom), 126.6 (s, CH-arom), 126.5 (s, CH-arom SiClPh2), 124.7 (vt, N
= 2.8, CH-arom), 124.5 (vt, N = 31.2, C-arom), 34.4 (s, C(CH3)2),
Reaction of 2 with HSiEt3: Preparation of IrHCl(SiEt3){xant-
(PiPr2)2} (6). Triethylsilane (27 μL, 0.16 mmol) was added to a
solution of 2 (100 mg, 0.15 mmol) in toluene (3 mL). After the
12115
dx.doi.org/10.1021/ic401931y | Inorg. Chem. 2013, 52, 12108−12119

Inorganic Chemistry
Article
29.4 (s, C(CH3)2), 24.6 (vt, N = 31.2, PCH(CH3)2), 18.9 (vt, N = 4.5,
PCH(CH3)2), 17.7 (s, PCH(CH3)2). 31P{1H} NMR (121.49 MHz,
C6D6, 293 K, δ): 47.9 (s). 29Si{1H} NMR (59.63 MHz, C6D6, 293 K,
δ): −4.8 (t, JSi−P = 20).
= 7.5, 2H, CH-arom), 2.52 (m, 2H, PCH(CH3)2), 1.56 (t, JH−H = 7.5,
9H, Si(CH2CH3)3), 1.39 (m, 12H PCH(CH3)2 + 6H Si(CH2CH3)3),
1.27 (s, 6H, CH3), 1.10 (dvt, JH−H = 6.7, N = 13.2, 12H, PCH(CH3)2).
13C{1H} NMR (100.62 MHz, C6D6, 293 K, δ): 155.9 (vt, N = 13.6, C-
arom), 131.8 (vt, N = 4.0, C-arom), 130.9 (s, CH-arom), 126.5 (s,
CH-arom), 126.7 (vt, N = 12.5, C-arom), 123.9 (s, CH-arom), 34.4 (s,
C(CH3)2), 30.4 (s, C(CH3)2), 26.6 (dvt, JC−Rh = 3.3, N = 20.7,
PCH(CH3)2), 20.6 (vt, N = 4.2, PCH(CH3)2), 18.5 (s, PCH(CH3)2),
13.7 (dt, JC−Rh = 5.6, JC−P = 3.2, Si(CH2CH3)3), 11.1 (s,
Si(CH2CH3)3). 31P{1H} NMR (161.98 MHz, C6D6, 293 K, δ): 46.0
(d, JP−Rh = 171.3). 29Si{1H} NMR (59.63 MHz, C6D6, 293 K, δ): 25.0
(dt, JSi−Rh = 54, JSi−P = 19).
Reaction of 6 with 2.0 equiv of H2SiPh2. In an NMR tube 6
(23.5 mg, 0.03 mmol) was dissolved in benzene-d6 (0.4 mL), and
diphenylsilane (11.5 μL, 0.06 mmol) was added. The tube was then
immersed in an oil bath at 50 °C, and the reaction was monitored by
1
1H and 31P{1H} NMR spectroscopy. After 26 h, the H and 31P{1H}
NMR spectra show signals corresponding to 6, 5, and 9 in a 50:26:24
molar ratio.
Reaction of RhH{xant(PiPr2)2} (8) with HSiEt3 at Low
Temperature: Spectroscopic Detection of RhH2(SiEt3){xant-
(PiPr2)2} (10). A screw-top NMR tube containing a solution of 8 (26.7
mg, 0.05 mmol) in toluene-d8 and cooled at 195 K was treated with
HSiEt3 (7.8 μL, 0.05 mmol). Immediately the NMR tube was
introduced in a NMR probe precooled at 258 K. The immediate and
quantitative conversion to RhH2(SiEt3){xant(PiPr2)2} (10) was
observed by 1H and 31P{1H} NMR spectroscopies (in solution at
Reaction of RhH{xant(PiPr2)2} (8) with HSiPh3 at Room
Temperature: Preparation of Rh(SiPh3){xant(PiPr2)2} (13).
Triphenylsilane (54.0 mg, 0.20 mmol) was added to a solution of 8
(100.0 mg, 0.18 mmol) in toluene (3 mL). After the resulting solution
was stirred for 1 h at room temperature, it was evaporated to dryness
to afford a dark residue. Addition of pentane afforded a red solid that
was washed with pentane (2 × 1 mL) and dried in vacuo. Yield: 120.0
mg (81%). Anal. Calcd. for C45H55OP2RhSi: C, 67.15; H, 6.89. Found:
C, 66.76; H, 6.62. HRMS (electrospray, m/z): calcd. for
C45H56OP2RhSi [M + H]+: 805.2625; found: 805.2616. IR (cm−1):
ν(C−O−C) 1103 (m). 1H NMR (300.13 MHz, C6H6, 293 K, δ): 8.38
(d, JH−H = 8.2, 6H, CH SiPh3), 7.30 (t, JH−H = 7.5, 6H, CH SiPh3),
7.21 (d, JH−H = 7.5, 3H, CH SiPh3), 7.20 (m, 2H, CH-arom), 7.12 (d,
JH−H = 7.6, 2H, CH-arom), 6.88 (t, JH−H = 7.6, 2H, CH-arom), 1.63
(m, 4H, PCH(CH3)2), 1.28 (s, 6H, CH3), 1.06 (dvt, JH−H = 7.2, N =
16.6, 12H, PCH(CH3)2), 0.99 (dvt, JH−H = 7.0, N = 13.0, 12H,
PCH(CH3)2). 13C{1H} NMR (75.46 MHz, C6D6, 293 K, δ): 155.9 (vt,
N = 13.8, C-arom), 149.1 (dt, JC−Rh= 2.7, JC−P = 2.3, C-arom SiPh3),
138.5 (s, CH-arom SiPh3), 131.7 (vt, N = 5.1, C-arom), 131.2 (s, CH-
arom), 126.8 (s, CH-arom SiPh3), 126.7 (s, CH-arom), 126.6(s, CH-
arom SiPh3), 125.6 (dvt, JC−Rh = 1.8, N = 14.5, C-arom), 124.1 (vt, N =
3.5, CH-arom), 34.4 (s, C(CH3)2), 30.5 (s, C(CH3)2), 25.5 (dvt, JC−Rh
= 3.0, N = 19.4, PCH(CH3)2), 20.5 (vt, N = 8.4, PCH(CH3)2), 17.9 (s,
PCH(CH3)2). 31P{1H} NMR (121.50 MHz, C6D6, 293 K, δ): 44.7 (d,
JP−Rh = 159). 29Si{1H} NMR (59.63 MHz, C6D6, 293 K, δ): 14.4 (dt,
JSi−Rh = 66, JSi−P = 21).
1
this temperature 12 was observed as a minor product with time). H
NMR (400.13 MHz, C7D8, 258 K, δ): 7.06 (m, 2H, CH-arom), 6.93
(dd, JH−H = 7.5, JH−H = 1.2, 2H, CH-arom), 6.85 (t, JH−H = 7.5, 2H,
CH-arom), 2.44 (m, 4H, PCH(CH3)2), 1.46 (t, JH−H = 7.7, 9H,
Si(CH2CH3)3), 1.32 (dvt, JH−H = 8.4, N = 15.9, 12H, PCH(CH3)2),
1.24 (m, 6H, Si(CH2CH3)3), 1.16 (s, 6H, CH3), 1.10 (dvt, JH−H = 6.7,
N = 13.5, 12H, PCH(CH3)2), −5.63 (dt, JH−Rh = 17.6, JH−P = 18.0, 2H,
RhH2). 13C{1H} NMR (100.62 MHz, C7D8, 258 K, δ): 156.8 (vt, N =
11.5, C-arom), 133.7 (vt, N = 4.7, C-arom), 129.0 (s, CH-arom), 125.0
(s, CH-arom), 123.5 (vt, N = 3.9, CH-arom), 122.7 (vt, N = 26.2, C-
arom), 34.8 (s, C(CH3)2), 26.2 (br, C(CH3)2), 25.0 (s, PCH(CH3)2),
19.4 (vt, N = 7.9, PCH(CH3)2), 18.2 (br, PCH(CH3)2), 16.8 (s,
Si(CH2CH3)3), 10.7 (s, Si(CH2CH3)3). 31P{1H} NMR (161.98 MHz,
C7D8, 258 K, δ): 61.6 (d, JP−Rh = 126). 29Si{1H} NMR (79.49 MHz,
C7D8, 258 K, δ): 33.0 (dt, JSi−Rh = 33, JSi−P = 9).
Reaction of RhH{xant(PiPr2)2} (8) with HSiPh3 at Low
Temperature: Spectroscopic detection of RhH2(SiPh3){xant-
(PiPr2)2} (11). A solution of HSiPh3 (12.9 mg, 0.05 mmol) in 0.5 mL
of toluene-d8 was added to a screw-top NMR tube containing 8 (27
mg, 0.05 mmol) and cooled at 195 K. Immediately the NMR tube was
introduced into a NMR probe precooled at 258 K. The immediate and
quantitative conversion to RhH2(SiPh3){xant(PiPr2)2} (11) was
observed by 1H and 31P{1H} NMR spectroscopies (in solution at
Reaction of Rh(SiClPh2){xant(PiPr2)2} (7) with NaBArF ·2H2O:
Preparation of [RhH{Si(OH)Ph2}{xant(PiPr2)2}]BArF4 (14).4Sodium
tetrakis{3,5-bis(trifluoromethyl)phenyl}borate (NaBArF ·2H2O) (150
4
mg, 0.17 mmol) was added to a red solution of 7 (100 mg, 0.13 mmol)
in fluorobenzene (3 mL). After being stirred for 1 h at room
temperature, the resulting yellowish solution was evaporated to
dryness, affording a yellowish residue. The addition of dichloro-
methane afforded a suspension that was filtered through Celite to
remove the sodium salts. The solution thus obtained was evaporated
to dryness. Addition of pentane afforded a white solid that was washed
with pentane (3 × 1 mL) and dried in vacuo. Yield: 160.0 mg (76%).
Anal. Calcd. for C71H64BF24O2P2RhSi: C, 53.00; H, 4.00. Found: C,
53.40; H, 4.42. HRMS (electrospray, m/z): calcd. for C39H52O2P2RhSi
[M]+: 745.2261; found: 745.2294. IR (cm−1): ν(O−H) 3643 (w);
1
this temperature 13 was observed as a minor product with time). H
NMR (400.13 MHz, C7D8, 258 K, δ): 7.53 (d, JH−H = 5.8, 6H, CH-
arom), 7.27 (t, JH−H = 7.2, 6H, CH-arom), 7.22 (m,, 2H, CH-arom),
7.19 (d, JH−H = 1.9, 3H, CH-arom), 6.95 (d, JH−H = 7.5, 2H, CH-
arom), 6.84 (t, JH−H = 7.5, 2H, CH-arom), 2.08 (m, 4H, PCH(CH3)2),
1.24 (s, 6H, CH3), 1.01 (dvt, JH−H = 7.8, N = 15.4, 12H, PCH(CH3)2),
0.95 (dvt, JH−H = 6.3, N = 14.1, 12H, PCH(CH3)2), −5.02 (dt, JH−Rh
=
19.3, JH−P = 16.1, 2H, RhH2). 13C{1H} NMR (100.62 MHz, C7D8, 258
K, δ): 157.1 (vt, N = 11.4, C-arom), 148.9 (s, C-arom), 138.4 (s, CH-
arom), 136.1 (s, CH-arom), 133.8 (vt, N = 4.3, C-arom), 130.0 (s, CH-
arom), 129.3 (s, CH-arom), 128.3 (s, CH-arom), 123.9 (vt, N = 6.6,
CH-arom), 122.9 (vt, N = 26.0, C-arom), 35.0 (s, C(CH3)2), 29.8 (s,
C(CH3)2), 25.1 (vt, N = 19.7, PCH(CH3)2), 20.5, 17.7 (both s,
PCH(CH3)2). 31P{1H} NMR (161.98 MHz, C7D8, 258 K, δ): 59.3 (d,
JP−Rh = 120). 29Si{1H} NMR (79.49 MHz, C7D8, 258 K, δ): 9.4 (dt,
JSi−Rh = 42, JSi−P = 12).
1
ν(C−O−C) 1090 (m). H NMR (300.13 MHz, CD2Cl2, 233 K, δ):
7.80−7.30 (m, 28H, CH-arom), 3.25 (s, 1H, OH), 2.49 (m, 4H,
PCH(CH3)2), 1.91 (s, 3H, CH3), 1.75 (m, 4H, PCH(CH3)2), 1.34 (m,
3H CH3 + 6H PCH(CH3)2), 1.04 (m, 6H, PCH(CH3)2), 0.97 (m, 6H,
PCH(CH3)2), 0.21 (m, 6H, PCH(CH3)2), −17.43 (dt, JH−Rh = 39.4,
JH−P = 12.5, 1H, Rh−H). 13C{1H} NMR (75.47 MHz, CD2Cl2, 233 K,
Reaction of RhH{xant(PiPr2)2} (8) with HSiEt3 at Room
Temperature: Preparation of Rh(SiEt3){xant(PiPr2)2} (12).
Triethylsilane (33 μL, 0.20 mmol) was added to a solution of 8
(100.0 mg, 0.18 mmol) in toluene (3 mL). After the resulting solution
was stirred for 5 min at room temperature, it was evaporated to
dryness to afford a red residue. Addition of pentane afforded a red
solid that was washed with pentane (2 × 0.5 mL) and dried in vacuo.
Yield: 70.0 mg (58%). Anal. Calcd. for C33H55OP2RhSi: C, 59.99; H,
8.39. Found: C, 59.90; H, 8.20. HRMS (electrospray, m/z): calcd. for
C33H56OP2RhSi [M + H]+: 661.2625; found: 661.2612. IR (cm−1):
ν(C−O−C) 1102 (m). 1H NMR (400.13 MHz, C6D6, 293 K, δ): 7.33
(m, 2H, CH-arom), 7.12 (d, JH−H = 7.5, 2H, CH-arom), 6.92 (t, JH−H
δ): 162.2 (q, JC−B = 49.9, C-B ArF ), 157.8 (vt, N = 12.7, C-arom),
4
140.2 (dt, JC−Rh = 1.3, JP−C = 2.7, C-arom Si(OH)Ph), 135.2 (s, CH-
F
arom Ar4 ), 134.3 (vt, N = 5.7, C-arom), 131.4 (s, CH-arom
F
Si(OH)Ph), 130.9 (s, CH-arom Si(OH)Ph), 130.4 (s, C-arom Ar4 ),
129.7 (s, CH-arom), 129.3 (qq, JC−F = 31.4, JC−B = 2.9, C-CF3 ArF ),
4
128.3 (s, CH-arom Si(OH)Ph2), 127.8 (vt, N = 5.5, CH-arom), 125.0
(q JC−F = 272, CF3 ArF ), 119.2 (vt, N = 25.6, C-arom), 117.9 (spt,
JC−F = 3.7, CH-arom ArF4), 35.8 (s, C(CH3)2), 34.2 (s, C(CH3)2), 26.8
4
(vt, N = 27.4, PCH(CH3)2), 25.2 (s, C(CH3)2), 23.5 (vt, N = 18.8,
PCH(CH3)2), 20.3, 20.0, 18.2, 17.0 (all s, PCH(CH3)2). 31P{1H}
NMR (121.50 MHz, CD2Cl2, 233 K, δ): 52.1 (d, JP−Rh = 119).
12116
dx.doi.org/10.1021/ic401931y | Inorg. Chem. 2013, 52, 12108−12119

Inorganic Chemistry
Article
29Si{1H} NMR (59.63 MHz, CD2Cl2, 233 K): δ 26.1 (dt, JSi−Rh = 32,
JSi−P = 7).
arom), 73.8 (s, O-C), 31.7 (s, CH3). 29Si{1H} NMR (59.63 MHz,
CDCl3, 293 K, δ): −29.5 (s).
1
HSi(OPh)Ph2. H NMR (400.13 MHz, CDCl3, 293 K, δ): 7.65 (d,
Reactions of Alcoholysis of Diphenylsilane Catalyzed by
RhH{Si(OH)Ph2}{xant(PiPr2)2}]BArF4 (14). In a typical procedure, the
alcohol (except PhOH, that was dissolved in 200 μL of toluene) (1.57
mmol) was added via syringe to a solution of the catalyst (2.6 × 10−3
mmol), H2SiPh2 (1.57 mmol) in toluene (5 mL) placed into a 25 mL
flask attached to a gas buret and immersed in a 32 °C bath, and the
mixture was vigorously shaken (500 rpm) during the run. The reaction
was monitored by measuring the volume of the evolved hydrogen with
time until hydrogen evolution stopped. A representation of gas
evolution versus time is included as Supporting Information. The
solution was then passed through a column (silica gel) to remove the
catalyst. Removal of the solvent gave the silyl ether. The product was
JH−H = 6.4, 4H, CH-arom), 7.41−7.28 (m, 7H, CH-arom), 7.18−7.12
(m, 2H, CH-arom), 6.92 (m, 2H, CH-arom), 5.72 (s, 1H, Si-H).
13C{1H} NMR (100.61 MHz, CDCl3, 293 K, δ): 155.5 (s, C-arom),
134.8 (s, CH-arom), 133.0 (s, C-arom), 130.8 (s, C-arom), 129.8 (s,
CH-arom), 128.3 (s, CH-arom), 122.0 (s, CH-arom), 119.4 (s, CH-
arom). 29Si{1H} NMR (59.63 MHz, CDCl3, 293 K, δ): −19.8 (s).
Structural Analysis of Complexes 3, 6, 7, 9, 12, and 14.
Crystals suitable for the X-ray diffraction were obtained by slow
diffusion of pentane into solutions of 3 and 6 in toluene, of diethyl
ether into solutions of 14 in dichloromethane, and by slow evaporation
of benzene (7) or pentane (9 and 12). X-ray data were collected on a
Bruker Smart APEX (3, 6, 7) and Bruker Apex II CCD (9, 12, 14)
difractometers equipped with a normal focus, 2.4 kW sealed tube
source (Mo radiation, λ = 0.71073 Å) operating at 50 kV and 30 (7,
12) or 40 (3, 6, 9, 14) mA. Data were collected over the complete
sphere by a combination of four sets. Each frame exposure time was 10
s (7, 14), 20 s (3, 6), 30 s (9), or 40 s (12) covering 0.3° in ω. Data
were corrected for absorption by using a multiscan method applied
with the SADABS program.29 The structures were solved by the
Patterson (Rh atom of 3, 7, 12, and 14, and Ir atoms of 6 and 9) or
direct methods and conventional Fourier techniques and refined by
full-matrix least-squares on F2 with SHELXL97.30 Anisotropic
parameters were used in the last cycles of refinement for all non-
hydrogen atoms. The hydrogen atoms were observed or calculated and
refined freely or using a restricted riding model. Hydride ligands were
observed in the difference Fourier maps but refined with restrained
bond length. One of the benzene crystallization molecules of 7 and
1
analyzed by H, 13C{1H}, and 29Si{1H} NMR spectroscopy.
Spectroscopic Data of the Products of the Monoalcoholysis.
1
HSi(OMe)Ph2. H NMR (300.13 MHz, CDCl3, 293 K, δ): 7.58 (dd,
JH−H = 7.6, JH−H = 1.9, 4H, CH-arom), 7.42−7.24 (m, 6H, CH-arom),
5.37 (s, 1H, Si-H), 3.54 (s, 3H, CH3). 13C{1H} NMR (75.47 MHz,
CDCl3, 293 K, δ): 134.8 (s, CH-arom), 133.8 (s, C-arom), 130.5 (s,
CH-arom), 128.2 (s, CH-arom), 52.5 (s, O-CH3). 29Si{1H} NMR
(59.63 MHz, CDCl3, 293 K, δ): −14.5 (s).
1
HSi(OEt)Ph2. H NMR (300.13 MHz, CDCl3, 293 K, δ): 7.62 (dd,
JH−H = 7.7, JH−H = 1.8, 4H, CH-arom), 7.42−7.34 (m, 6H, CH-arom),
5.41 (s, 1H, Si-H), 3.84 (q, JH−H = 7.0, 2H, CH2), 1.24 (t, JH−H = 7.0,
3H, CH3). 13C{1H} NMR (75.47 MHz, CDCl3, 293 K, δ): 134.8 (s,
CH-arom), 134.3 (s, C-arom), 130.4 (s, CH-arom), 128.1 (s, CH-
arom), 60.7 (s, O-CH2), 18.3 (s, CH3). 29Si{1H} NMR (59.63 MHz,
CDCl3, 293 K, δ): −17.6 (s).
HSi(OnBu)Ph2. 1H NMR (400.13 MHz, CDCl3, 293 K, δ): 7.60 (dd,
JH−H = 7.8, JH−H = 1.7, 4H, CH-arom), 7.39−7.32 (m, 6H, 2H, CH-
arom), 5.40 (s, 1H, Si-H), 2.19 (t, JH−H = 6.5, 2H, CH2), 1.57 (m, 2H,
CH2), 1.36 (m, 2H, CH2), 0.86 (t, JH−H = 7.4, 3H, CH3). 13C{1H}
NMR (100.61 MHz, CDCl3, 293 K): δ 134.8 (s, CH-arom), 134.3 (s,
C-arom), 130.4 (s, CH-arom), 128.1 (s, CH-arom), 64.7 (s, O-CH2),
34.7 (s, CH2), 19.1 (s, CH2), 13.9 (s, CH3) . 29Si{1H} NMR (59.63
MHz, CDCl3, 293 K, δ): −17.4 (s).
two of the CF3 groups of the BArF anion of 14 were found to be
4
disordered. These disordered atoms were refined isotropically with
restrained geometry. For all structures, the highest electronic residuals
were observed in the close proximity of the metal centers and make no
chemical sense.
Crystal Data for 3. C39H52ClOP2RhSi·0.5C7H8, MW 811.26,
colorless, prism (0.15 × 0.13 × 0.09), monoclinic, space group C2/
c, a: 31.6766(18) Å, b: 11.6863(7) Å, c: 22.6325(13) Å, β =
107.2060(10)°, V = 8003.2(8) Å3, Z = 8, Dcalc: 1.347 g cm−3, F(000):
3400, T = 100(2) K, μ 0.635 mm−1. 39319 measured reflections (2θ:
4−57°, ω scans 0.3°), 9550 unique (Rint = 0.0454); minimum/
maximum transmission factors 0.748/0.862. Final agreement factors
were R1 = 0.0471 (7392 observed reflections, I > 2σ(I)) and wR2 =
0.1203; data/restraints/parameters 9550/0/436; GOF = 1.056.
Largest peak and hole 1.683 and −0.504 e/Å3.
Crystal Data for 6. C33H56ClIrOP2Si, MW 786.46, colorless, prism
(0.18 × 0.07 × 0.06), monoclinic, space group C2/c, a: 38.867(3) Å, b:
9.4817(8) Å, c: 18.9847(16) Å, β = 90.5580(10)°, V = 6995.9(10) Å3,
Z = 8, Dcalc: 1.493 g cm−3, F(000): 3200, T = 100(2) K, μ 4.043 mm−1.
31 121 measured reflections (2θ: 4−57°, ω scans 0.3°), 8313 unique
(Rint = 0.0428); minimum/maximum transmission factors 0.582/
0.862. Final agreement factors were R1 = 0.0441 (7026 observed
reflections, I > 2σ(I)) and wR2 = 0.1140; data/restraints/parameters
8313/1/368; GOF = 1.064. Largest peak and hole 4.199 and −2.541
e/Å3.
1
HSi(OnOctyl)Ph2. H NMR (400.13 MHz, CDCl3, 293 K, δ): 7.61
(dd, JH−H = 7.8, JH−H = 1.6, 4H, CH-arom), 7.40−7.33 (m, 6H, CH-
arom), 5.40 (s, 1H, Si-H), 3.75 (t, JH−H = 6.4, 2H, CH2), 1.58 (m, 2H,
CH2), 1.35−1.15 (m, 10H, CH2), 0.86 (t, JH−H = 6.7, 3H, CH3).
13C{1H} NMR (100.61 MHz, CDCl3, 293 K, δ): 134.8 (s, CH-arom),
134.3 (s, C-arom),130.4 (s, CH-arom), 128.1 (s, CH-arom), 65.1 (s,
O-CH2), 32.5, 32.0, 29.4, 25.9, 22.8 (all s, CH2), 14.3 (s, CH3).
29Si{1H} NMR (59.63 MHz, CDCl3, 293 K, δ): −17.4 (s).
1
HSi(OCH2Ph)Ph2. H NMR (400.13 MHz, CDCl3, 293 K, δ): 7.62
(dd, JH−H = 7.9, JH−H = 1.5, 4H, CH-arom), 7.41−7.28 (m, 11H, CH-
arom), 5.47 (s, 1H, Si-H), 4.83 (s, 2H, CH2). 13C{1H} NMR (100.61
MHz, CDCl3, 293 K, δ): 140.2 (s, C-arom), 134.8 (s, CH-arom), 133.8
(s, C-arom), 130.6, 128.4, 128.2, 127.4, 126.9 (all s, CH-arom), 66.7 (s,
CH2). 29Si{1H} NMR (59.63 MHz, CDCl3, 293 K, δ): −16.1 (s).
1
HSi(OiPr)Ph2. H NMR (300.13 MHz, CDCl3, 293 K): δ 7.60 (dd,
JH−H = 7.6, JH−H = 1.9, 4H, CH-arom), 7.43−7.29 (m, 6H, CH-arom),
5.44 (s, 1H, SiH), 4.15 (sept, JH−H = 6.1, 1H, CH), 1.21(d, JH−H = 6.1,
6H, CH3). 13C{1H} NMR (75.47 MHz, CDCl3, 293 K): δ 135.0 (s, C-
arom), 134.8 (s, CH-arom), 130.3 (s, CH-arom), 128.1 (s, CH-arom),
67.5 (s, O-CH), 25.4 (s, CH3). 29Si{1H} NMR (59.63 MHz, CDCl3,
293 K, δ): −20.5 (s).
Crystal Data for 7. C39H50ClOP2RhSi·2C6H6, MW 919.40, red,
prism (0.22 × 0.13 × 0.09), triclinic, space group P1, a: 10.2599(7) Å,
̅
b: 11.9553(8) Å, c: 20.3304(14) Å, α = 77.8960(10)°, β =
84.2760(10)°, γ = 71.9240(10)°, V = 2316.3(3) Å3, Z = 2, Dcalc
:
HSi(OCy)Ph2. 1H NMR (400.13 MHz, CDCl3, 293 K, δ): 7.61 (dd,
JH−H = 7.8, JH−H = 1.7, 4H, CH-arom), 7.39−7.31 (m, 6H, CH-arom),
5.38 (s, 1H, Si-H), 3.72 (m, 1H, CH), 1.57, 1.77−1.11 (m, 10H, CH2).
13C{1H} NMR (100.61 MHz, CDCl3, 293 K, δ): 135.0 (s, C-arom),
134.7 (s, CH-arom), 130.3 (s, CH-arom), 128.1 (s, CH-arom), 73.1 (s,
O-CH), 35.4, 25.7, 24.2 (all s, CH2) . 29Si{1H} NMR (59.63 MHz,
CDCl3, 293 K, δ): −20.9 (s).
1.318 g cm−3, F(000): 964, T = 120(2) K, μ 0.557 mm−1. 27059
measured reflections (2θ: 2−57°, ω scans 0.3°), 10623 unique (Rint
=
0.0386); minimum/maximum transmission factors 0.642/0.862. Final
agreement factors were R1 = 0.0460 (8775 observed reflections, I >
2σ(I)) and wR2 = 0.0940; data/restraints/parameters 10623/0/488;
GOF = 1.071. Largest peak and hole 0.747 and −0.793 e/Å3.
Crystal Data for 9. C39H52ClIrOP2Si·1/4(C5H12), MW 872.52,
colorless, irregular prism (0.16 × 0.14 × 0.10), monoclinic, space
group C2/c, a: 23.228(3) Å, b: 23.110(3) Å, c: 17.543(2) Å, β =
122.110(2)°, V = 7976.6(16) Å3, Z = 8, Dcalc: 1.453 g cm−3, F(000):
3540, T = 100(2) K, μ 3.554 mm−1. 43 448 measured reflections (2θ:
HSi(OtBu)Ph2. 1H NMR (400.13 MHz, CDCl3, 293 K, δ): 7.60 (dd,
JH−H = 7.7, JH−H = 1.8, 4H, CH-arom), 7.40−7.30 (m, 6H, CH-arom),
5.55 (s, 1H, Si-H), 1.31 (s, 9H, CH3). 13C{1H} NMR (100.61 MHz,
CDCl3, 293 K, δ): 136.2 (s, C-arom), 134.6, 130.0, 128.0 (all s, CH-
12117
dx.doi.org/10.1021/ic401931y | Inorg. Chem. 2013, 52, 12108−12119

Inorganic Chemistry
Article
2−59°, ω scans 0.3°), 10458 unique (Rint = 0.0488); minimum/
maximum transmission factors 0.487/0.704. Final agreement factors
were R1 = 0.0323 (7537 observed reflections, I > 2σ(I)) and wR2 =
0.0804; data/restraints/parameters 10458/5/435; GOF = 0.941.
Largest peak and hole 2.390 and −1.020 e/Å3.
(4) Alos
́ ́
, J.; Bolano, T.; Esteruelas, M. A.; Olivan, M.; Onate, E.;
̃ ̃
Valencia, M. Inorg. Chem. 2013, 52, 6199.
(5) Recent findings on Rh(POP) chemistry: (a) Goldman and co-
workers have described the synthesis and reactivity of related rhodium
complexes with xant(PtBu2)2 and 2,5-bis((di-tert-butylphosphino)
methyl)furan. See: Haibach, M. C.; Wang, D. Y.; Emge, T. J.;
Krogh-Jespersen, K.; Goldman, A. S. Chem. Sci. 2013, 4, 3683. (b)
Weller and co-workers have reported on the hydroacylation of alkynes
catalyzed by Rh-DPEphos complexes. See: Pawley, R. J.; Huertos, M.
A.; Lloyd-Jones, G. C.; Weller, A. S.; Willis, M. C. Organometallics
2012, 31, 5650. (c) Haynes and co-workers have isolated an acetyl-
Rh-xantphos complex during the study of the mechanism of methanol
carbonylation. See: Williams, G. L.; Parks, C. M.; Smith, C. R.; Adams,
H.; Haynes, A.; Meijer, A. J. H. M.; Sunley, G. J.; Gaemers, S.
Organometallics 2011, 30, 6166. (d) Julian and Hartwig have
discovered a Rh-POP catalyst for the intramolecular hydroamination
of aminoalkenes. See: Julian, L. D.; Hartwig, J. F. J. Am. Chem. Soc.
2010, 132, 13183.
(6) Esteruelas, M. A.; Olivan
5339.
(7) Corey, J. Y. Chem. Rev. 2011, 111, 863.
(8) (a) Roy, A. K. Adv. Organomet. Chem. 2008, 55, 1. (b) Normand,
A. T.; Cavell, K. J. Eur. J. Inorg. Chem. 2008, 2781. (c) Troegel, D.;
Stohrer, J. Coord. Chem. Rev. 2011, 255, 1440.
(9) See for example: (a) Esteruelas, M. A.; Herrero, J.; Lop
Martín, M.; Oro, L. A. Organometallics 1999, 18, 1110. (b) Díaz, J.;
Crystal Data for 12. C33H55OP2RhSi, MW 660.71, dark red, prism
(0.17 × 0.12 × 0.07), orthorhombic, space group P2(1)2(1)2(1), a:
8.5450(9) Å, b: 18.3095(19) Å, c: 22.353(2) Å, V = 3497.3(6) Å3, Z =
4, Dcalc: 1.255 g cm−3, F(000): 1400, T = 100(2) K, μ 0.637 mm−1. 37
385 measured reflections (2θ: 3−59°, ω scans 0.3°), 9055 unique (Rint
= 0.0629); minimum/maximum transmission factors 0.747/0.944.
Final agreement factors were R1 = 0.0337 (7333 observed reflections, I
> 2σ(I)) and wR2 = 0.0665; Flack parameter 0.44(2); data/restraints/
parameters 9055/0/357; GOF = 0.955. Largest peak and hole 1.056
and −0.457 e/Å3.
Crystal Data for 14. C71H64BF24O2P2RhSi·OC4H10, MW 1683.09,
colorless, prism (0.23 × 0.22 × 0.17), triclinic, space group P1, a:
̅
10.1457(10) Å, b: 19.559(2) Å, c: 19.979(2) Å, α = 87.073(2) °, β =
88.661(2) °, γ = 77.015(2) °, V = 3858.0(7) Å3, Z = 2, Dcalc: 1.449 g
cm−3, F(000): 1716, T = 100(2) K, μ 0.382 mm−1. 42965 measured
reflections (2θ: 3−59°, ω scans 0.3°), 19600 unique (Rint = 0.0360);
minimum/maximum transmission factors 0.778/0.944. Final agree-
ment factors were R1 = 0.0498 (14559 observed reflections, I > 2σ(I))
and wR2 = 0.1389; data/restraints/parameters 19600/18/978; GOF =
1.062. Largest peak and hole 1.491 and −0.839 e/Å3.
́ ́
, M.; Velez, A. Inorg. Chem. 2013, 52,
́
ez, F. M.;
ASSOCIATED CONTENT
■
Esteruelas, M. A.; Herrero, J.; Moralejo, L.; Olivan
195, 187. (c) Esteruelas, M. A.; Herrero, J.; Olivan
́
, M. J. Catal. 2000,
, M. Organometallics
S
* Supporting Information
́
CIF files giving positional and displacement parameters,
crystallographic data, and bond lengths and angles of
compounds 3, 6, 7, 9, 12, and 14. NMR spectra of complexes
10 and 11 and a plot of hydrogen evolution versus time for the
monoalcoholysis of diphenylsilane catalyzed by complex 14.
This material is available free of charge via the Internet at
http://pubs.acs.org.
2004, 23, 3891. (d) Yang, J.; Brookhart, M. J. Am. Chem. Soc. 2007,
129, 12656. (e) Yang, J.; Brookhart, M. Adv. Synth. Catal. 2009, 351,
175.
(10) See for example: (a) Goikhman, R.; Aizenberg, M.; Shimon, L. J.
W.; Milstein, D. J. Am. Chem. Soc. 1996, 118, 10894. (b) Field, L. D.;
Messerle, B. A.; Rehr, M.; Soler, L. P.; Hambley, T. W. Organometallics
2003, 22, 2387. (c) Chandrasekhar, V.; Boomishankar, R.; Nagendran,
S. Chem. Rev. 2004, 104, 5847. (d) Muraoka, T.; Abe, K.; Haga, Y.;
Nakamura, T.; Ueno, K. J. Am. Chem. Soc. 2011, 133, 15365.
(11) (a) Yang, J.; White, P. S.; Schauer, C. K.; Brookhart, M. Angew.
Chem., Int. Ed. 2008, 47, 4141. (b) Yang, J.; White, P. S.; Brookhart, M.
J. Am. Chem. Soc. 2008, 130, 17509. (c) Park, S.; Brookhart, M. J. Am.
Chem. Soc. 2012, 134, 640.
(12) (a) Calimano, E.; Tilley, T. D. J. Am. Chem. Soc. 2008, 130,
9226. (b) Calimano, E.; Tilley, T. D. J. Am. Chem. Soc. 2009, 131,
11161. (c) Calimano, E.; Tilley, T. D. Organometallics 2010, 29, 1680.
(d) Calimano, E.; Tilley, T. D. Dalton Trans. 2010, 39, 9250.
(13) Gatard, S.; Chen, C.-H.; Foxman, B. M.; Ozerov, O. V.
Organometallics 2008, 27, 6257.
AUTHOR INFORMATION
■
Corresponding Author
*E-mail: maester@unizar.es.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
Financial support form the MINECO of Spain (Projects
CTQ2011-23459 and Consolider Ingenio 2010 CSD2007-
(14) Goikhman, R.; Aizenberg, M.; Ben-David, Y.; Shimon, L. J. W.;
Milstein, D. Organometallics 2002, 21, 5060.
(15) (a) Johnson, C. E.; Eisenberg, R. J. Am. Chem. Soc. 1985, 107,
00006), the Diputacion
and the European Social Fund is acknowledged. We are very
́ ́
General de Aragon (E-35), FEDER,
grateful to Dr. Enrique Onate for collecting the X-ray
̃
6531. (b) Esteruelas, M. A.; Lahoz, F. J.; Olivan
A. Organometallics 1995, 14, 3486. (c) Esteruelas, M. A.; Olivan
Oro, L. A. Organometallics 1996, 15, 814.
́
, M.; Onate, E.; Oro, L.
̃
diffraction data.
́
, M.;
REFERENCES
(16) See for example: (a) Osakada, K.; Koizumi, T.; Yamamoto, T.
Organometallics 1997, 16, 2063. (b) Osakada, K.; Sarai, S.; Koizumi,
T.; Yamamoto, T. Organometallics 1997, 16, 3973. (c) Turculet, L.;
Feldman, J. D.; Tilley, T. D. Organometallics 2004, 23, 2488.
(d) McBee, J. L.; Tilley, T. D. Organometallics 2009, 28, 5072.
■
(1) (a) Albrecht, M.; van Koten, G. Angew. Chem., Int. Ed. 2001, 40,
3750. (b) van der Boom, M. E.; Milstein, D. Chem. Rev. 2003, 103,
1759. (c) Singleton, J. T. Tetrahedron 2003, 59, 1837. (d) The
Chemistry of Pincer Compounds; Morales-Morales, D.; Jensen, C. M.,
Eds.; Elsevier Science: Amsterdam: The Netherlands, 2007.
(e) Benito-Garagorri, D.; Kirchner, K. Acc. Chem. Res. 2008, 41, 201.
(f) Whited, M. T.; Grubbs, R. H. Acc. Chem. Res. 2009, 42, 1607.
(g) Choi, J.; MacArthur, A. H. R.; Brookhart, M.; Goldman, A. S.
Chem. Rev. 2011, 111, 1761. (h) Haibach, M. C.; Kundu, S.;
Brookhart, M.; Goldman, A. S. Acc. Chem. Res. 2012, 45, 947.
(e) Hoffmann, F.; Wagler, J.; Bohme, U.; Roewer, G. J. Organomet.
̈
Chem. 2012, 705, 59.
(17) Esteruelas, M. A.; Oro, L. A. Coord. Chem. Rev. 1999, 193−195,
557.
(18) See for example: (a) Fernandez, M. J.; Esteruelas, M. A.;
́
Covarrubias, M.; Oro, L. A.; Apreda, M.-C.; Foces-Foces, C.; Cano, F.
H. Organometallics 1989, 8, 1158. (b) Esteruelas, M. A.; Lahoz, F. J.;
(2) Asensio, G.; Cuenca, A. B.; Esteruelas, M. A.; Medio-Simon
Olivan, M.; Valencia, M. Inorg. Chem. 2010, 49, 8665.
(3) Esteruelas, M. A.; Honczek, N.; Olivan, M.; Onate, E.; Valencia,
M. Organometallics 2011, 30, 2468.
́
, M.;
Onate, E.; Oro, L. A.; Rodríguez, L. Organometallics 1996, 15, 823.
̃
́
́
́
(c) Vicent, C.; Viciano, M.; Mas-Marza, E.; Sanau, M.; Peris, E.
́
̃
Organometallics 2006, 25, 3713. (d) Sangtrirutnugul, P.; Tilley, T. D.
12118
dx.doi.org/10.1021/ic401931y | Inorg. Chem. 2013, 52, 12108−12119

Inorganic Chemistry
Article
Organometallics 2007, 26, 5557. (e) Bleeke, J. R.; Thananatthanachon,
T.; Rath, N. P. Organometallics 2008, 27, 2436.
(19) Square-planar rhodium(I)-silyl complexes are somewhat rare:
(a) Thorn, D.; Harlow, R. L. Inorg. Chem. 1990, 29, 2017.
(b) Aizenberg, M.; Milstein, D. Science 1994, 265, 359. (c) Hoffmann,
P.; Meier, C.; Hiller, W.; Heckel, M.; Riede, J.; Schmidt, U. J.
Organomet. Chem. 1995, 490, 51. (d) Mitchell, G. P.; Tilley, T. D.;
Yap, G. P. A.; Rheingold, A. L. Organometallics 1995, 14, 5472.
(e) Aizenberg, M.; Ott, J.; Elsevier, C. J.; Milstein, D. J. Organomet.
Chem. 1998, 551, 81.
(20) Hendriksen, D. E.; Oswald, A. A.; Ansell, G. B.; Leta, S.;
Kastrup, R. V. Organometallics 1989, 8, 1153.
(21) See for example: (a) van der Veen, L. A.; Keever, P. H.;
Schoemaker, G. C.; Reek, J. N. H.; Kamer, P. C. J.; van Leeuwen, P. W.
N. M.; Lutz, M.; Spek, A. L. Organometallics 2000, 19, 872. (b) Fox, D.
J.; Duckett, S. B.; Flaschenriem, C.; Brennessel, W. W.; Schneider, J.;
Gunay, A.; Eisenberg, R. Inorg. Chem. 2006, 45, 7197. (c) Marimuthu,
T.; Bala, M. D.; Friedrich, H. B. J. Coord. Chem. 2009, 62, 1407.
(d) Jian, Y.; Peng, S.; Li, X.; Wen, X.; He, J.; Jiang, L.; Dang, Y. Inorg.
Chim. Acta 2011, 368, 37. (e) Pontiggia, A. J.; Chaplin, A. B.; Weller,
A. S. J. Organomet. Chem. 2011, 696, 2870.
(22) (a) Bolano, T.; Castarlenas, R.; Esteruelas, M. A.; Onate, E. J.
̃
̃
Am. Chem. Soc. 2007, 129, 8850.
(23) Hubler, K.; Hunt, P. A.; Maddock, S. M.; Rickard, C. E. F.;
̈
Roper, W. R.; Salter, D. M.; Schwerdtfeger, P.; Wright, L. J.
Organometallics 1997, 16, 5076.
(24) Findlater, M.; Bernskoetter, W. H.; Brookhart, M. J. Am. Chem.
Soc. 2010, 132, 4534.
(25) See for example: (a) Luo, X. L.; Crabtree, R. H. J. Am. Chem.
Soc. 1989, 111, 2527. (b) Doyle, M. P.; High, K. G.; Bagheri, V.;
Pieters, R. J.; Lewis, P. J.; Pearson, M. M. J. Org. Chem. 1990, 55, 6082.
(c) Barber, D. E.; Lu, Z.; Richardson, T.; Crabtree, R. H. Inorg. Chem.
1992, 31, 4709. (d) Chang, S.; Scharrer, E.; Brookhart, M. J. Mol.
Catal. A: Chem. 1998, 130, 107.
(26) Werner, H. Angew. Chem., Int. Ed. Engl. 1983, 22, 927.
(27) (a) Kim, S.; Chang, H. Bull. Chem. Soc. Jpn. 1985, 58, 3669.
́
(b) DSa, B. A.; McLeod, D.; Verkade, J. G. J. Org. Chem. 1997, 62,
5057.
(28) Brookhart, M.; Grant, B.; Volpe, A. F., Jr. Organometallics 1992,
11, 3920.
(29) Blessing, R. H. Acta Crystallogr. 1995, A51, 33. SADABS: Area-
detector absorption correction; Bruker-AXS: Madison, WI, 1996.
(30) SHELXTL, Package v. 6.10; Bruker-AXS: Madison, WI, 2000.
Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112.
12119
dx.doi.org/10.1021/ic401931y | Inorg. Chem. 2013, 52, 12108−12119