An η3-H2SiR2 adduct of [{PhB-(CH 2PiPr2)3}FeIIH]

Article abstract of DOI:10.1002/anie.200502527

Reaction of the high-spin iron(II) alkyl complex [{PhB(CH ₂PiPr₂)₃}FeMe] with phenylsilane or mesitylsilane affords unusual diamagnetic silane adducts of the iron(II) hydride [{PhB(CH₂PiPr₂)₃}FeH]. An η³ bonding mode in these silane adducts has been established by NMR spectroscopy, X-ray crystallography, and DFT methods. Rapid interconversion ofs the hydride positions in solution via a silylene intermediate is proposed. (Chemical Equation Presented)

Full text of DOI:10.1002/anie.200502527

Communications
Silanes
DOI: 10.1002/anie.200502527
An h3-H2SiR2 Adduct of [{PhB-
(CH2PiPr2)3}FeIIH]**
Christine M. Thomas and Jonas C. Peters*
The tripodal tris(phosphino)borate ligand [PhB(CH2PiPr2)3]À
(abbreviated [PhBPiPr3]) stabilizes iron complexes in a wide
IV [1]
range ofoxidation states, including high-valent Fe
.
[(PhBPiPr3)FeLn] systems are, moreover, known to mediate a
[*] C. M. Thomas, Professor J. C. Peters
Division of Chemistry and Chemical Engineering
Arnold and Mabel Beckman Laboratories of Chemical Synthesis
California Institute of Technology
Pasadena, CA 91125 (USA)
Fax: (+1)626-577-4088
E-mail: jpeters@caltech.edu.
[**] This work was supported by the NSF (CHE-01232216) and BP (MC2
program). Larry Henling and Dr. Mike Day are acknowledged for
crystallographic assistance, and Erin J. Daida is acknowledged for
executing several preliminary screen reactions. We also thank the
referees of this manuscript for several insightful suggestions.
Supporting information for this article is available on the WWW
under http://www.angewandte.org or from the author.
776
ꢀ 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2006, 45, 776 –780

Angewandte
Chemie
II
number oftwo-electron redox transformations, including Fe
/
FeIV oxidative group transfer and oxidative addition/reductive
elimination processes.[1a,c] In the latter context, it was recently
demonstrated that four-coordinate iron alkyl species of the
type [(PhBPiPr3)FeIIR] undergo facile hydrogenolysis to gen-
erate iron(iv) trihydrides ofthe type [(PhBP 3)FeIV(H)3-
iPr
(PR3)] that can be likewise generated by H2 addition to
[(PhBPiPr3)FeII(H)(PR3)] precursors.[1c] These complexes
mediate catalytic olefin hydrogenation, most likely through
uncommon FeII/FeIV oxidative addition/reductive elimination
Scheme 1. Reaction of 1 with phenylsilane.
steps.[1c] Motivated by these findings, we have examined the
methane loss is detected by 1H NMR spectroscopy. The
31P{1H} NMR spectrum of 2 reveals a broad singlet at d =
76 ppm, which is consistent with a C3v-symmetric structure.
All three phosphorus nuclei remain magnetically equivalent
in the 31P{1H} NMR spectrum at temperatures as low as
À808C. The 1H NMR spectrum of 2 reveals a hydride signal at
d = À13.5 ppm with a complicated splitting pattern (see
below).
iPr
reactivity ofthese ofur-coordinate [(PhBP
3)FeIIR] alkyl
species with silane substrates for comparison with their
reactivity towards H2, anticipating that structurally distinctive
iron silylene species might be generated. Herein, we report
the structural and spectroscopic characterization ofunusual
h3-silane adducts ofiron( ii), namely [(PhBPiPr3)FeII(H)(h3-
H2SiR2)]. As described below, the available structural,
spectroscopic, and theoretical data also suggest the possibility
that the [(PhBPiPr3)FeII(H)(h3-H2SiR2)] systems described
herein equilibrate via silylene intermediates ofthe type
[(PhBPiPr3)FeIV(H)3(SiR2)].[2] Such silylene intermediates
would be isoelectronic with the previously reported
[(PhBPiPr3)FeIV(H)3(PR3)] but appear to be too high in
energy relative to their ground state [(PhBPiPr3)FeII(H)(h3-
H2SiR2)] isomers to be directly observed.
To assess the structure ofcomplex 2 in the solid state, X-
ray quality single crystals were grown by cooling a concen-
trated solution of 2 in diethyl ether to À358C. High-resolution
X-ray diffraction analysis provided the solid-state structure
shown in Figure 1.[10] The structure confirms that a 1,2-methyl
migration occurs from the iron center to the silicon center
during the transformation. A remarkably short Fe···Si dis-
tance of2.1280(7) Š is present that is very similar to the
Fe···Si distance of2.154(1) Š reported of r the only structur-
ally characterized example ofan iron silylene species,
Although silicon-containing transition-metal complexes
that exhibit h2-HSiR3 interactions are ubiquitous,[3,4] those
that exhibit well-characterized interactions between two or
more metal hydrides and a coordinated silicon atom are much
less common. These interactions have never-
[Cp*Fe(CO)(SiMes2)SiMe3]
(Mes = 2,4,6-Me3C6H2).[11]
Moreover, the geometry ofthe silicon atom of 2 is rigorously
theless been described in certain cases, such as in
the dinuclear complex [{(PR3)2(H)2Ru}2(h4-
[5]
SiH4)] ofSabo-Etienne and co-workers
and
in the mononuclear complexes [ReH4(PPh3)(h3-
H2SiR3)],[6] [(PCy3)2Ru(H)(h2-H2)(h3-H2SiPh3)]
(Cy = cyclohexyl),[7] [Ru(PPh3)3H3SiMeCl2],[8]
and [Cp*Ru(PPh3)(h3-H2SiMeCl2)] (Cp* =
C5Me5).[9] Metal hydride/silyl systems ofthese
types are often described as lying somewhere
along the continuum to oxidative addition, the
limit being full oxidative addition with earlier,
“arrested” addition stages also being com-
mon.[4a] To the best ofour knowledge, the
[(PhBPiPr3)FeII(H)(h3-H2SiR2)] complexes de-
scribed here are the first thoroughly character-
ized examples ofarrested silane adducts ofiron
that exhibit an h3 binding mode (i.e., Fe(h3-
H2SiR2)). The only other example ofthis binding
mode for a silane ligand of any transition-metal
complex appears to be the aforementioned
[5]
dinuclear ruthenium system ofSabo-Etienne.
A [(PhBPiPr3)FeII(H)(h3-H2SiR2)] species is
formed
by
the
reaction
between
[(PhBPiPr3)FeMe] (1) and PhSiH3 (Scheme 1),
which leads to the quantitative formation of a
single diamagnetic red product (2), as evidenced
by 1H NMR spectroscopy. In contrast to the
Figure 1. Solid-state molecular structure of [(PhBPiPr3)FeII(H)(H2SiPhMe)] (2) and
[(PhBPiPr3)FeII(H)(H2SiMesMe)] (3) showing 50% displacement ellipsoids. Only one of the two
independent molecules present in the asymmetric unit of 3 is shown. Hydrogen atoms other
previously reported reaction of 1 with H2,[1c] no than the hydrides of interest have been omitted for clarity.
Angew. Chem. Int. Ed. 2006, 45, 776 –780
ꢀ 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
777

Communications
Table 1: Interatomic distances for 2 as determined by X-ray crystallog-
raphy and a DFT (B3LYP/LACVP**) geometry optimization.
planar (aC2-Si-Fe + aC2-Si-C1 + aC1-Si-Fe = 3608) if
one considers its connectivity to the phenyl, methyl, and iron
substituents only. These structural data suggested a Si atom
with silylene character and led to our initial, but ultimately
incorrect, assignment of 2 as a silylene trihydride ofstructure
type B (Scheme 1). All three hydride positions could be
located in the difference Fourier map and refined, and careful
examination reveals that two ofthe hydrides (H1 and H3) are
located within bonding distance ofboth the iron and the
Experimental [Š]
Calculated [Š]
À
Fe Si
À
Fe H1
2.1280(7)
1.553(1)
1.482(1)
1.566(2)
1.464(1)
2.001(2)
1.552(2)
2.166
1.555
1.484
1.569
1.469
2.073
1.554
À
Fe H2
À
Fe H3
À
Si H1
À
Si H2
À
Si H3
À
À
À
silicon centers (Fe H1: 1.55 Š; Fe H3: 1.57 Š; Si H1:
À
1.46 Š; Si H3: 1.55 Š). The third hydride (H2) is located
outside the typical bonding radius ofthe silicon atom
tions is less than 20 kJmolÀ1. Interactions below this energy
are ignored by NBO analaysis.[13,15] Therefore, the experi-
mentally observed close contact between the iron center and
(2.00 Š)[4b] and resides appreciably closer to the Fe center
À
(Fe H2: 1.48 Š). These data are inconsistent with the silylene
À
À
structure B.
the silicon–hydride bonds Si H1 and Si H3 is best charac-
terized as h3 in character. Likewise, any interaction between
the iron hydride H2 and the Si center would also be
characterized as an attractive interaction, although likely
one ofa much weaker nature ifit is present at all. Complexes
2 and 3 are therefore best described as h3 silane adducts ofan
iron(ii) hydride (structure type A in Scheme 1) and not as
iron(iv) silylene trihydrides (structure type B).
As there is inevitable uncertainty in accurately locating
the positions ofhydrogen atoms close to much heavier atoms
such as Si and Fe by X-ray crystallography, a related complex
was prepared for additional structural support of the assign-
ment. In an analogous reaction to that shown in Scheme 1,
complex 1 reacts with one equivalent ofmesitylsilane
(H3SiMes) to generate a diamagnetic red product (3) in
quantitative yield. Complex 3 displays analogous NMR data
to that of 2, with a 31P{1H} shift at d = 79 ppm and a hydride-
type 1H NMR resonance at d = À13.4 ppm, which also
suggests a highly symmetric structure in solution. X-ray
quality crystals could be obtained in a similar way, and one of
the two independent molecules present in the asymmetric
unit is shown in Figure 1.[12] As in the case of 2, two ofthe
three hydrides are located within bonding distance ofthe
Further inspection ofthe solution-state NMR data
available for 2 confirms that a significant Si···H interaction
is also maintained in the solution phase. A T1min measurement
of177 ms ( À308C, [D8]toluene) was determined for the
hydride resonance ofthe 1H NMR spectrum. This large value
would appear to rule out the presence ofa nonclassical
dihydrogen adduct species (h2-H2) but does not help to
distinguish between a classical hydride formulation versus the
2
À
À
À À
silicon atom in each molecule (Si H5: 1.56 and 1.62 Š; Si
H6: 1.67 and 1.74 Š), while the third hydride appears to be
outside the bonding radius ofthe Si atom (Si···H4: 2.14 and
1.97 Š). The Fe···Si distances in both molecules for 3 (2.131(1)
h -Si H Fe interaction suggested by the crystallographic and
DFT data.[16,17] Simulation ofthe hydride signal (Figure 2)
and 2.141(1) Š) are essentially identical to that in
(2.1280(7) Š). Regardless ofthe inevitable uncertainty in
2
the specific Fe···H and Si···H distances, the significant
similarity between the structures of 2 and 3 strongly suggests
the presence oftwo 3-centered Fe-H-Si interactions in the
solid state and one Fe-H(hydride) interaction.
For additional structural examination ofthe hydride
positions, a density functional (DFT) geometry optimization
ofthe structure of 2 was performed using the Jaguar package
(B3LYP/LACVP**).[13,14] All ofthe atoms of 2 were used in
the calculation, and the structure was minimized using the
experimentally determined crystallographic coordinates as an
À
À
initial estimate. The resulting Fe H and Si H bond lengths
were very similar to those determined by crystallography
(Table 1). Interestingly, perturbing the crystallographic coor-
dinates to provide a more threefold symmetric structure
without Si-H interactions as a starting point led to the same
structural minimum. It is gratifying to note that the DFT
model locates two short and one much longer Si···H distance,
which is in accord with the h3-H2SiR2 adduct formulation.
Accordingly, a natural bond orbital (NBO) analysis predicts
Figure 2. Experimental (solid) and simulated (dotted) 1H NMR spec-
trum of 2 (500 MHz, 258C, C6D6) in the hydride region. See text for
discussion.
reveals that its complicated splitting pattern arises from first-
order coupling ofeach equivalent hydride to one trans
phosphorus atom (2JP-H = 27 Hz) and two cis phosphorus
atoms (2JP-H = 3 Hz). The coupling pattern is complicated by
second-order effects that result from phosphorus–phosphorus
coupling (2JP-P = 62 Hz). Accordingly, the hydride signal
appears as a singlet in the 1H{31P} NMR spectrum. The
second-order splitting pattern ofthe hydride signal in the
only two Si H bonding orbitals (Si H1, Si H3).[15] Likewise,
only one Fe H bonding orbital is predicted (Fe H2) and no
bonding orbital is located between Si and Fe. The cutoff
energy for locating a bond for donor–acceptor-type interac-
À
À
À
À
À
778
www.angewandte.org
ꢀ 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2006, 45, 776 –780

Angewandte
Chemie
1H NMR spectrum changes as the temperature ofthe solution
decreases, which indicates a fluxional process of some type
(see Supporting Information). Decoalescence of the signal,
however, likely occurs at temperatures well below those
examined (À808C).
Likewise, a number ofmechanistic pathways to account
for the overall formation of 2 and 3 can be envisioned. Two
plausible mechanisms are shown in Scheme 2. In view ofthe
propensity for the [PhBPiPr3]Fe scaffold to undergo two-
The 29Si{1H} NMR data obtained for 2 and 3 reveal signals
at d = 162 and 160 ppm,[18] respectively. These values are
significantly downfield of known classical transition-metal–
silyl adducts (d = À120 to 90 ppm) but are also upfield of
reported transition-metal silylenes (d = > 200 ppm).[4a,2]
Although monomeric complexes containing h2-HSiR3 inter-
actions display a wide range ofchemical shifts in the 29Si{1H}
NMR spectrum (from d = À28 to 55 ppm),[3,4a] the unusually
large downfield shifts observed for 2 and 3 are likely reflective
3
À
ofthe h nature ofthe silane ligand and the very close Fe Si
contact that results, as evident from the solid-state structures.
Closer inspection ofthe hydride signals for both 2 and 3
reveals the presence of 29Si satellites that provide JSi-H cou-
pling values of68 and 70 Hz, respectively. The rapid exchange
ofthe hydrides in solution means that the actual 29Si coupling
Scheme 2. Two possible mechanisms for the formation of 2.
can be determined by the following equation: Jobs = 1/3[2”
electron redox processes, it is perhaps most reasonable to
propose an oxidative addition/reductive elimination mecha-
nism as shown in path a.[1] In this scenario, the first step is
coordination ofsilane followed by an oxidative addition to the
FeII center. Reductive 1,2-methyl migration from iron to
silicon then affords an isomer of 2 (or 3). A sigma-bond
metathesis (pathway b) also provides a convenient and
potentially low energy methyl-migration pathway. No inter-
mediates could be detected when the reaction between 1 and
PhSiH3 was monitored by 1H NMR spectroscopy at low
temperature (À508C, [D8]toluene).
2
1JSi-H(h2)
+
2JSi-H(terminal)].[19] Ifit is assumed that JSi-H(terminal) is
1
zero, maximum JSi-H(h2) values of102 and 105 Hz are pre-
dicted for 2 and 3, respectively. An HMQC experiment was
undertaken for each species to confirm these coupling
constants and to assign the solution structures of 2 and 3
definitively.[20] The data reveal a direct correlation between
the 29Si NMR signals of 2 and 3 and their corresponding
hydride signals in the 1H NMR spectrum (see Supporting
À
Information). These data further confirm that Si H inter-
actions exist for 2 and 3 both in solution and in the solid state.
On the basis ofthe structural, spectroscopic, and DFT
data, 2 and 3 are assigned as iron(ii) hydride complexes
Methane loss does not occur during the course ofthe
reaction between 1 and phenylsilane or mesitylsilane, whereas
such loss occurs readily when 1 is exposed to H2.[1c] To probe
the possibility that reversible methane loss and reactivation
might be occurring prior to methyl migration, a deuterium-
labeling study was undertaken. The deuterated methyl
species, [(PhBPiPr3)FeCD3] ([CD3]-1), is generated by addition
2
3
À
featuring two h -Si H interactions that give rise to h -H2SiR2
adducts of[(PhBP 3)FeIIH]. Although a third, very weak
iPr
attractive interaction with the hydride ligand cannot be fully
dismissed,[4d] such an interaction would need to be regarded as
highly distinct from that of the other two H atoms, in which a
strong interaction with both Si and Fe is evident. Whereas
three-centered, two-electron bonding interactions in 2 and 3
are apparent in their solid-state structures, all three hydrides
undergo rapid exchange in solution and appear to be chemi-
cally equivalent. It seems plausible to us that an iron(iv)
silylene trihydride, shown as structure type B in Scheme 1,
could be responsible for the rapid interconversion of the
hydride positions on the NMR time scale. As noted above,
isolobal [(PhBPiPr3)FeIV(H)3(PR3)] species are chemically
of[D ]MeLi to [(PhBPiPr3)FeCl]. Reaction between [CD3]-1
3
and
PhSiH3
results
in
the
formation
of
[(PhBPiPr3)Fe(H)(H2SiPhCD3)] ([CD3]-2) as the sole product,
as evidenced by 1H NMR data (see Supporting Information).
Likewise, the reaction between 1 and PhSiD3 results in the
formation of [(PhBPiPr3)Fe(D)(D2SiPhMe)] ([D],[D2-silyl]-2).
These experiments appear to rule out any incipient methane
formation prior to methyl migration.
Finally, 1 exhibits selectivity for primary silane substrates.
No reaction is observed between 1 and secondary or tertiary
silane substrates (e.g., Ph2SiH2 and Et3SiH) over extended
periods, presumably because such silanes cannot lead to the
thermodynamically stable h3-silane adduct structures. Secon-
dary silane substrates do react, however, if 1 is exposed to H2
in their presence. For example, 1 reacts with MePhSiH2 to
produce 2 quantitatively under a blanket ofhydrogen
(Scheme 3). Examination ofthis reaction sequence at low
temperature (À208C, [D8]toluene) reveals methane loss and
the initial formation of the previously reported trihydride
species [(PhBPiPr3)FeH3] prior to product formation.[1c]
[(PhBPiPr3)FeH3] gradually decays as 2 appears. This sequence
À
stable within this system, and the extremely short Fe Si
bond length, together with the planar nature around the Si
center with respect to the methyl, phenyl, and iron substitu-
ents, suggests that virtually no structural reorganization
would be required at the Si center under such a scenario.
An alternative mechanism for interconversion concerns an
intermediate in which the Si center interacts equivalently with
all three H atoms. This would give rise to a [(PhBPiPr3)Fe(h4-
H3SiR2)] intermediate. The possibility ofa weak interaction
between the Si center and the hydride ligand in the ground-
state structures of 2 and 3 would set the stage for this type of
dynamic pathway.[3g]
Angew. Chem. Int. Ed. 2006, 45, 776 –780
ꢀ 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
779

Communications
2
À
[4] For reviews that cover h -Si H interactions, see: a) J. Y. Corey, J.
Braddock-Wilking, Chem. Rev. 1999, 99, 175; b) U. Schubert,
Adv. Organomet. Chem. 1990, 30, 151; c) G. I. Nikonov, J.
Organomet. Chem. 2001, 635, 24; d) Z. Lin, Chem. Soc. Rev.
2002, 31, 239; e) G. J. Kubas, MetalDihydrogen and Sigma Bond
Complexes: Structure, Theory, and Reactivity, Kluwer Academic,
New York, 2001.
[5] a) I. Atheaux, B. Donnadieu, J.-C. Daran, S. Sabo-Etienne, B.
Chaudret, K. Hussein, J.-C. Barthelat, J. Am. Chem. Soc. 2000,
122, 5664; b) R. Ben Said, K. Hussein, J.-C. Barthelat, I.
Atheaux, S. Sabo-Etienne, M. Grellier, B. Donnadieu, B.
Chaudret, Dalton Trans. 2003, 4139.
Scheme 3. Reaction of 1 with MePhSiH2 under H2.
[6] X.-L. Luo, D. Baudry, P. Boydell, P. Charpin, M. Nierlich, M.
Ephritikhine, R. H. Crabtree, Inorg. Chem. 1990, 29, 1511.
[7] K. Hussein, C. J. Marsden, J.-C. Barthelat, V. Rodriguez, S.
Conejero, S. Sabo-Etienne, B. Donnadieu, B. Chaudret, Chem.
Commun. 1999, 1315.
suggests that 1 reacts with H2 to generate a reactive hydride
source that is then trapped by silane, analogous to the
trapping ofsuch hydride species by the addition ofa
phosphine donor.[1c]
[8] N. M. Yardy, F. R. Lemke, Organometallics 2001, 20, 5670.
[9] A. L. Osipov, S. M. Gerdov, L. G. Kuzmina, J. A. K. Howard,
G. I. Nikonov, Organometallics 2005, 24, 587.
In conclusion, it has been found that the [(PhBPiPr3)FeMe]
À
complex reacts with primary aryl silanes to mediate Si H
[10] Crystallographic data for [(PhBPiPr3)FeII(H)(H2SiPhMe)] (2):
Mr = 660.51, red block, collection temperature = 100 K, triclinic,
bond activations and 1,2-methyl migrations that generate
unusual h3-H2SiRMe silane adducts of[(PhBP iPr3)FeIIH] (R =
Ph, Mes). These iron complexes serve as relatives to the
numerous Group 8 complexes ofthe general type [L 3M-
(ER3)H3] (E = Si, Sn; M = Fe, Ru, Os) now known.[21] The key
distinction to be drawn is that the complexes described herein
feature a less-substituted Si atom that strongly attracts two
À
¯
space group P1, a = 11.3852(12), b = 12.0036(13), c =
16.1029(17) Š, a = 95.172(2), b = 107.352(2), g = 95.805(2)8,
V= 2072.9(4) Š3, Z = 2, R1 = 0.0309 [I > 2s(I)], GOF = 1.068.
CCDC-273356 (2) contains the supplementary crystallographic
data for this paper. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
Fe H bonds—resulting in the formation of
a
[11] H. Tobita, A. Matsuda, H. Hashimoto, K. Ueno, H. Ogino,
Angew. Chem. 2004, 116, 223; Angew. Chem. Int. Ed. 2004, 43,
221.
[(PhBPiPr3)Fe(H)(h3-H2SiR2)] complex with a very short
Fe···Si distance that is distinct from, but closely associated
with, its silylene isomer [(PhBPiPr3)Fe(H)3(SiR2)].
[12] Crystallographic data for [(PhBPiPr3)Fe(H)(H2SiMesMe)] (3):
Mr = 702.59, red block, collection temperature = 100 K, ortho-
rhombic, space group P212121, a = 18.1126(13), b = 20.3251(14),
c = 21.6417(16) Š, V= 7967.2(10) Š3, Z = 8, R1 = 0.0609 [I >
2s(I)], GOF = 1.677. CCDC-27358 (3) contains the supplemen-
tary crystallographic data for this paper. These data can be
obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
[13] Jaguar 5.0, Schrodinger, LLC, Portland, Oregon, 2002.
[14] C. Lee, W. Yang, R. G. Parr, Phys. Rev. B 1988, 37, 785.
[15] NBO 5.0, E. D. Glendening, J. K. Badenhoop, A. E. Reed, J. E.
Carpenter, J. A. Bohmann, C. M. Morales, F. Weinhold, Theo-
retical Chemistry Institute, University ofWisconsin, Madison,
2001; http://www.chem.wisc.edu/ ꢀ nbo5.
Received: July 19, 2005
Revised: October 12, 2005
Published online: December 21, 2005
Keywords: borates · iron · phosphanes · silanes
.
[1] a) T. A. Betley, J. C. Peters, J. Am. Chem. Soc. 2004, 126, 6252;
b) T. A. Betley, J. C. Peters, J. Am. Chem. Soc. 2003, 125, 10782;
c) E. J. Daida, J. C. Peters, Inorg. Chem. 2004, 43, 7474.
[2] For relevant examples oftransition-metal–silylene complexes,
see: a) J. C. Peters, J. D. Feldman, T. D. Tilley, J. Am. Chem. Soc.
1999, 121, 9871; b) B. V. Mork, T. D. Tilley, J. Am. Chem. Soc.
2004, 126, 4385; c) J. D. Feldman, J. C. Peters, T. D. Tilley,
Organometallics 2002, 21, 4065; d) P. B. Glaser, P. W. Wanandi,
T. D. Tilley, Organometallics 2004, 23, 693; e) C. Beddie, M. B.
Hall, J. Am. Chem. Soc. 2004, 126, 13564; f) P. Glaser, T. D.
Tilley, J. Am. Chem. Soc. 2003, 125, 13640.
[16] R. H. Crabtree, M. Lavin, L. Bonneviot, J. Am. Chem. Soc. 1986,
108, 4032.
[17] For comparison, the recently reported [(PhBPiPr3)Fe(H)3(PMe3)]
complex exhibits a T1min of140 ms. [1c]
[18] The 29Si{1H} signal for 3 appears as a sharp quartet (2JSi-P
61 Hz) while the signal for 2 is a broad singlet.
=
[19] F. L. Taw, R. G. Bergman, M. Brookhart, Organometallics 2004,
23, 886 – 890.
[3] For examples ofGroup 8 h2-silane adducts, see: a) S. C. Bart, E.
Lobkovsky, P. J. Chirik, J. Am. Chem. Soc. 2004, 126, 13794;
b) Y. Ohki, T. Kojima, M. Oshima, H. Suzuki, Organometallics
2001, 20, 2654; c) R. S. Simons, C. A. Tessier, Organometallics
1996, 15, 2604; d) E. Scharrer, M. Brookhart, J. Organomet.
Chem. 1995, 497, 61; e) U. Schubert, S. Gilbert, S. Mock, Chem.
Ber. 1992, 125, 835; f) E. Scharrer, S. Chang, M. Brookhart,
Organometallics 1995, 14, 5686; g) F. Delpech, S. Sabo-Etienne,
J.-C. Daran, B. Chaudret, K. Hussein, C. J. Marsden, J.-C.
Barthelat, J. Am. Chem. Soc. 1999, 121, 6668; h) I. Atheaux, F.
Delpech, B. Donnadieu, S. Sabo-Etienne, B. Chaudret, K.
Hussein, J.-C. Barthelat, T. Braun, S. B. Duckett, R. N. Perutz,
Organometallics 2002, 21, 5347; i) S. Lachaize, S. Sabo-Etienne,
B. Donnadieu, B. Chaudret, Chem. Commun. 2003, 214.
[20] R. M. Silverstein, F. X. Webster, The Spectrometric Identification
of Organic Compounds, 6th ed., Wiley, New York, 1998, chap. 6,
pp. 262.
[21] For examples, see: a) S. Gilbert, M. Knorr, S. Mock, U. Schubert,
J. Organomet. Chem. 1994, 480, 241; b) L. J. Procopio, D. H.
Berry, J. Am. Chem. Soc. 1991, 113, 4039; c) C. E. F. Rickard,
W. R. Roper, S. D. Woodgate, L. J. Wright, J. Organomet. Chem.
2000, 609, 177; d) K. Hubler, U. Hubler, W. R. Roper, P.
Schwerdtfeger, L. J. Wright, Chem. Eur. J. 1997, 3, 1608 – 1616.
780
www.angewandte.org
ꢀ 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2006, 45, 776 –780