Unexpected formation of polydentate phosphinoalkyl-silyl and -germyl ligands from reaction of [MoH4(Ph2PCH2CH 2PPh2)2] with organosilanes and organogermanes: Novel activation of Mo-H, E-H (E = Si, Ge), and C-H bonds in the same system

Article abstract of DOI:10.1021/om0401298

Reaction of [MoH₄(Ph₂PCH₂CH ₂PPh₂)₂] (1) with PhEH₃ (E = Si, Ge) in refluxing toluene yielded the novel complexes [MoH₃{[Ph ₂PCH₂CH₂P(Ph)C₆H₄-o] ₂(Ph)E-P,P,P,P,E}] (E = Si (2), Ge (3)) with a quinquidentate ligand comprised of a P-P-E-P-P framework as a result of the oxidative addition involving E-H bond cleavage with concomitant selective activation of the ortho C-H bonds of the two dppe ligands. When secondary Ph₂SiH₂ was employed in a similar reaction with 1, a trihydrido complex with a tridentate ligand ([Ph₂PCH₂CH₂P-(Ph)C ₆H₄-o]Ph₂Si-P,P,Si) comprised of a P-P-Si framework was isolated. On the other hand, the reaction between Ph ₂GeH₂ and 1 proceeded with accompanying evolution of 1 mol of benzene to give 3; that is, in addition to the Ge-H and C-H activation, Ge-C(Ph) bond cleavage took place. It is concluded that the reaction path includes the intermediacy of silylene or germylene metal complexes via an α-migration process on the basis of deuterium-labeling studies.

Full text of DOI:10.1021/om0401298

3434
Organometallics 2005, 24, 3434-3441
Unexpected Formation of Polydentate
Phosphinoalkyl-Silyl and -Germyl Ligands from
Reaction of [MoH4(Ph2PCH2CH2PPh2)2] with
Organosilanes and Organogermanes: Novel Activation of
Mo-H, E-H (E ) Si, Ge), and C-H Bonds in the Same
System
Makoto Minato,* Da-Yang Zhou, Li-Bin Zhang, Ryo Hirabayashi,
Masaki Kakeya, Takaomi Matsumoto, Akifumi Harakawa,
Gosuke Kikutsuji, and Takashi Ito*
Department of Materials Chemistry, Graduate School of Engineering, Yokohama National
University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, Japan 240-8501
Received November 16, 2004
Reaction of [MoH4(Ph2PCH2CH2PPh2)2] (1) with PhEH3 (E ) Si, Ge) in refluxing toluene
yielded the novel complexes [MoH3{[Ph2PCH2CH2P(Ph)C6H4-o]2(Ph)E-P,P,P,P,E}] (E ) Si
(2), Ge (3)) with a quinquidentate ligand comprised of a P-P-E-P-P framework as a result
of the oxidative addition involving E-H bond cleavage with concomitant selective activation
of the ortho C-H bonds of the two dppe ligands. When secondary Ph2SiH2 was employed in
a similar reaction with 1, a trihydrido complex with a tridentate ligand ([Ph2PCH2CH2P-
(Ph)C6H4-o]Ph2Si-P,P,Si) comprised of a P-P-Si framework was isolated. On the other hand,
the reaction between Ph2GeH2 and 1 proceeded with accompanying evolution of 1 mol of
benzene to give 3; that is, in addition to the Ge-H and C-H activation, Ge-C(Ph) bond
cleavage took place. It is concluded that the reaction path includes the intermediacy of silylene
or germylene metal complexes via an R-migration process on the basis of deuterium-labeling
studies.
Introduction
elimination from the silyl- or germyl-hydridometal
complexes are generally accepted to be reversible; they
involve η2-E-H (E ) Si, Ge) σ complexes as the com-
mon intermediates. Recently Kubas and co-workers
have examined the reaction of molybdenum complexes,
Mo(CO)(R2PCH2CH2PR2)2 (R ) Ph or Et), with silanes5
and germanes.6 They observed the formation of σ-silane
or σ-germane complexes, which are in tautomeric equi-
librium with their oxidative addition products in solu-
tion. They pointed out that studies of the interaction
between such Mo(PP)2 (PP ) diphosphine) complexes
and the E-H bond may provide valuable insight into
the factors that influence catalytic transformations of
organosilanes and organogermanes.
Compounds that contain an interelement linkage1 of
M-E (M ) transition metals; E ) group 14 elements)
have a longstanding history in the field of organome-
tallic chemistry. They are highly important as active
species in catalytic addition of the linkage to unsatur-
ated organic substrates. Most of the effort in this area
has been focused on the synthesis of silicon complexes.2
A metal-silicon single bond is unique and often displays
unusual properties, such as unexpectedly short bond
distances or high bond energies, which are not yet fully
understood.3 In addition, the electron-releasing proper-
ties and strong trans influence of silyl ligands may alter
or enhance the catalytic performance of transition-metal
catalysts.4
We have reported versatile reactivities of the coordi-
natively unsaturated intermediate MoHn(dppe)2 (n ) 2,
0; dppe ) Ph2PCH2CH2PPh2), which is generated pho-
tochemically or thermally from [MoH4(dppe)2] (1),7
The oxidative addition of organosilanes or organoger-
manes to transition-metal complexes and their reductive
* To whom correspondence should be addressed. E-mail: minato@
ynu.ac.jp (M.M.). Tel: +81-45-339-3933. Fax: +81-45-339-3933.
(1) Tamao, K.; Yamaguchi, S. J. Organomet. Chem. 2000, 611, 3.
(2) (a) Tilley, T. D. In The Chemistry of Organic Silicon Compounds;
Patai, S., Rappoport, Z., Eds.; Wiley: New York, 1989; Chapter 24, p
1415. (b) Tilley, T. D. In The Silicon-Heteroatom Bond; Patai, S.,
Rappoport, Z., Eds.; Wiley: New York, 1991; Chapters 9 and 10, pp
245-309. (c) Pannell, K. H.; Sharm, H. Chem. Rev. 1995, 95, 1351. (d)
Eisen, M. S. In The Chemistry of Organic Silicon Compounds; Apeloig,
Y., Rappoport, Z., Eds.; Wiley: New York, 1998; Vol. 2, Chapter 35, p
2037. (e) Corey, J. Y.; Braddock-Wilking, J. Chem. Rev. 1999, 99, 175.
(3) (a) Aylett, B. J. Adv. Inorg. Chem. Radiochem. 1982, 25, 1. (b)
Cundy, C. S.; Kingston, B. M.; Lappert, M. F. Adv. Organomet. Chem.
1973, 11, 253.
(4) (a) Brost, R. D.; Bruce, G. C.; Joslin, F. L.; Stobart, S. R.
Organometallics 1997, 16, 5669. (b) Minato, M.; Matsumoto, T.;
Ichikawa, M.; Ito, T. Chem. Commun. 2003, 2968. (c) Minato, M.; Zhou,
D.-Y.; Sumiura, K.; Hirabayashi, R.; Yamaguchi, Y.; Ito, T. Chem.
Commun. 2001, 2654.
(5) (a) Luo, X.-L.; Kubas, G. J.; Bryan, J. C.; Burns, C. J.; Unkefer,
C. J. J. Am. Chem. Soc. 1994, 116, 10312. (b) Luo, X.-L.; Kubas, G. J.;
Burns, C. J.; Bryan, J. C.; Unkefer, C. J. J. Am. Chem. Soc. 1995, 117,
1159.
(6) Vicent, J. L.; Luo, S.; Scott, B. L.; Butcher, R.; Unkefer, C. J.;
Burns, C. J.; Kubas, G. J.; Lledo´s, A.; Maseras, F.; Tomas, J.
Organometallics 2003, 22, 5307.
(7) Meakin, P.; Guggenberger, L. J.; Peet, W. G.; Muetterties, E.
L.; Jesson, J. P. J. Am. Chem. Soc. 1973, 95, 1467.
10.1021/om0401298 CCC: $30.25 © 2005 American Chemical Society
Publication on Web 05/28/2005

Polydentate Phosphinoalkyl-Silyl and -Germyl Ligands
Organometallics, Vol. 24, No. 14, 2005 3435
Scheme 1
toward various substrates involving the selective C-H,
C-O, O-H, or N-H bond cleavage.8 On the basis of
these studies, we have studied the reactivity of 1 toward
organosilanes and organogermanes. To our surprise, the
resulting polyhydrido complexes possess unusual quin-
tuply chelated ligands comprised of a P-P-E-P-P
framework. Preliminary accounts have been published.9
Results and Discussion
Reaction of 1 with 1 Equiv of Primary Silanes
and Germane in Toluene. Heating a toluene solution
of 1 under reflux in the presence of 1 equiv of PhEH3
for 3 h afforded the unanticipated complexes 2 (E ) Si)
and 3 (E ) Ge) as yellow solids (Scheme 1).
In the solid state, the complexes are stable indefinitely
under an inert atmosphere; in organic solvents, they are
also stable in the absence of oxygen. It is well-known
that polyhydrido silyl-containing transition-metal com-
plexes are often not isolated but, instead, lose dihydro-
gen to afford transition-metal silyl products. As a
consequence, relatively few polyhydrido transition-metal
silyl complexes have been characterized.10
Complexes 2 and 3 exhibited very similar spectro-
scopic features and will be described and discussed
together. The IR spectra of these complexes showed
ν(Mo-H) at 1714 cm-1 for 2 and at 1808 cm-1 for 3. We
could not observe the characteristic E-H absorptions11
at around 2100 cm-1, suggesting that these bonds are
absent in the resulting complexes.
Figure 1. ORTEP drawing of the molecular structure
of 3.
1
ligand was found to be 3:8. Low-temperature H NMR
(-50 °C, toluene-d8) only led to broadening of the
hydrido groups. However, we observed that, on raising
the temperature, these signals gradually coalesced and
finally became a simple quintet (2, 90 °C; 3, 105 °C).
Upon cooling of the samples to room temperature, the
signals returned to their original multiplet patterns.
T1 measurements in 1H NMR are a useful method for
distinguishing classical from nonclassical structures in
transition-metal polyhydrides.12 In complex 2, the T1
values measured at room temperature at 400 MHz were
found to be 90 ms for the signal at δ -4.45 ppm and 96
ms for the signal at δ -4.15 ppm. These values seem to
be consistent with a coordinate classical polyhydride.12c
The 31P{1H} NMR spectra of 2 and 3 revealed two
doublets (2, δ 81.4, 110.2; 3, δ 83.8, 113.8) with coupling
constant values of 61 (2) and 55 Hz (3), indicating the
presence of two chemically different P nuclei. There
were virtually no changes in the 31P{1H} NMR spectra
of 2 in toluene-d8 measured at room temperature and
at 90 °C.
To determine the bonding pattern for the new complex
3, a single-crystal X-ray analysis was carried out (Figure
1). Yellow crystals of 3 suitable for the analysis were
obtained by recrystallization from toluene/hexane at 0
°C. Selected bond lengths and angles are listed in Table
1. Although the hydride ligands were not able to be
located directly in the molecular structure, their pres-
ence was confirmed by means of 1H NMR spectroscopy
(vide supra). As shown in Figure 1, the structure reveals
a striking feature, in which the phenylgermanium group
and the two dppe ligands are now linked by new
carbon-germanium bonds. Thus, complex 3 contains
bonds between the germanium atom and the ortho
carbons of the phenyl groups in the dppe ligands
constructing a novel quinquidentate ligand. The forma-
tion of complex 3 is itself very novel, because activation
The 1H NMR spectra of the complexes in benzene-d6
at room temperature showed multiplet signals between
δ -3.9 and -4.7 ppm for 2 and between δ -3.7 and -4.6
ppm for 3. These signals in the high-field region are
assignable to Mo-H protons; they are analyzed as a set
of a broad triplet (2, δ -4.15; 3, δ -3.90) with apparent
coupling constant values of 33 (2) and 48 Hz (3) and a
broad quintet (2, δ -4.45; 3, δ -4.40) with apparent
coupling constant values of 35 (2) and 29 Hz (3). The
integration ratio of the former and the latter was found
to be 1:2. In addition, the ratio of the total intensity of
these signals to that of the CH2CH2 signals in the dppe
(8) (a) Ito, T.; Tosaka, H.; Yoshida, S.; Mita, K.; Yamamoto, A.
Organometallics 1986, 5, 735. (b) Ito, T.; Hamamoto, K.; Kurishima,
S.; Osakada, K. J. Chem. Soc., Dalton Trans. 1990, 1645. (c) Kurishima,
S.; Matsuda, N.; Tamura, N.; Ito, T. J. Chem. Soc., Dalton Trans. 1991,
1135. (d) Ito, T.; Kurishima, S.; Tanaka, M.; Osakada, K. Organome-
tallics 1992, 11, 2333. (e) Minato, M.; Kurishima, S.; Nagai, K.; Ito,
T.; Yamasaki, M. Chem. Lett. 1994, 2339. (f) Minato, M.; Sakai, H.;
Weng, Z.-G.; Zhou, D.-Y.: Kurishima, S.; Ito, T.; Yamasaki, M.; Shiro,
M.; Tanaka, M.; Osakada, K. Organometallics 1996, 15, 4863.
(9) (a) Zhou, D.-Y.; Minato, M.; Ito, T.; Yamasaki, M. Chem. Lett.
1997, 1017. (b) Zhou, D.-Y.: Zhang, L.-B.; Minato, M.; Ito, T.; Osakada,
K. Chem. Lett. 1998, 187. (c) Minato, M.; Hirabayashi, R.; Matsumoto,
T.; Yamaguchi, Y.; Ito, T. Chem. Lett. 2001, 960.
(10) Mo¨hlen, M.; Rickard, C. E. F.; Roper, W. R.; Salter, D. M.;
Wright, L. J. J. Organomet. Chem. 2000, 593-594, 458.
(12) (a) Hamilton, D. G.; Crabtree, R. H. J. Am. Chem. Soc. 1988,
110, 4126. (b) Bautista, M. T.; Earl, K. A.; Maltby, P. A.; Morris, R.
H.; Schweizer, C. T.; Sella, A. J. Am. Chem. Soc. 1988, 110, 7031. (c)
Luo, X.-L.; Crabtree, R. H. Inorg. Chem. 1990, 29, 2788.
(11) The IR spectra of PhEH3 showed ν(E-H) at 2157 cm-1 (E )
Si) and at 2072 cm-1 (E ) Ge).

3436 Organometallics, Vol. 24, No. 14, 2005
Minato et al.
Table 1. Interatomic Distances (Å) and Angles
(deg) for 3
Table 2. Preparation of
[MoH3{[Ph2PCH2CH2P(Ph)C6H4-o]2(R)E-P,P,P,P,E}]
Distances
substrate
Mo1-P1
Mo1-P3
Ge1-Mo1
Ge1-C7
2.456(4)
2.449(5)
2.587(2)
1.96(2)
Mo1-P2
Mo1-P4
Ge1-C1
Ge1-C47
2.457(5)
2.436(5)
2.03(2)
2.03(2)
amt of
RSiH3 (R)/
amt, mmol
amt of
yield,
%
compd 1, mmol
toluene, mL
2a
2b
2c
2d
2e
2f
0.251
0.224
0.570
0.334
0.580
0.223
0.301
p-CH3C6H4/0.254
o-CH3C6H4/0.896
C6F5/0.860
4-(CH3)2NC6H4/0.502
n-C6H13/0.860
cyclo-C6H11/0.334
PhGeH3/0.301
20
20
15
15
40
40
30
75
83
85
85
75
79
60
Angles
80.6(2)
80.8(2)
76.8(1)
119.1(1)
125.5(7)
106.6(5)
101.4(8)
P1-Mo1-P2
P3-Mo1-P4
Ge1-Mo1-P1
Ge1-Mo1-P3
Mo1-Ge1-C1
Mo1-Ge1-C47
C7-Ge1-C47
P2-Mo1-P3
P1-Mo1-P4
Ge1-Mo1-P2
Ge1-Mo1-P4
Mo1-Ge1-C7
C1-Ge1-C7
C47-Ge1-C1
102.0(2)
98.8(2)
111.6(6)
93.9(1)
78.8(1)
106.8(9)
101.9(9)
3
peatedly unsatisfactory, except for 2f.14 However, the
similarity of the 1H and 31P{1H} NMR spectra of 2 and
3, along with the results of the following section,
strongly suggests that 2 and 3 have similar structures.
Reaction of 1 with Excess Primary Silanes in
Toluene. When the reaction was carried out in the
presence of more than 2 equiv of PhSiH3, a yellow solid
of 4 was obtained in 78% yield (Scheme 2). We found
that 4 is also derived from 2 by its reaction with excess
PhSiH3 in refluxing toluene. The fact that 4 and 2 were
obtained in a stepwise manner starting from 1 strongly
suggests that 4 is formed via oxidative addition of the
second molecule of PhSiH3 to 2.
X-ray-quality crystals of 4 were successfully grown
from a toluene/hexane solution. The molecular structure
is depicted in Figure 2; selected bond distances and
angles are listed in Table 4. There are two Si atoms in
the molecule: one (Si1) is present in the usual terminal
SiH2Ph ligand and another (Si2) contains bonds between
the silyl atom and the ortho carbons of the phenyl
groups in the dppe ligands, constructing a novel quin-
quidentate ligand.
The coordination environment of the molybdenum
atom is found to be entirely analogous to that of 3.
Hence, the reaction proceeded in a manner similar to
that in the case of the PhGeH3 system. Combustion
analysis data for the diffraction-quality crystals were
in accord with the formulation of the complex deter-
mined by the diffraction study. Although the hydride
ligands were not able to be located directly in the
molecular structure, their presence was confirmed by
means of 1H NMR spectroscopy (vide infra). It is
noteworthy that the Mo-Si1 bond distance of 2.620(2)
Å is slightly elongated relative to that of Mo-Si2 by
0.06 Å, suggestive of the exceptional character of the
silyl group as a trans-influencing ligand.15 The struc-
ture can be compared and contrasted with that of the
parent complex 1 and the germanium complex 3. The
P1-Mo-P3 bond angle of 101.39(7)° is nearly identical
to that found in 1 (101.56(2)°). In addition, the mean
Mo-P bond length of 2.471 Å in 4 is only slightly longer
than that exhibited by 1 (2.420 Å). These observations
indicate that the formation of the new bonds between
the silicon and the ortho carbons of the phenyl groups
of not only the Ge-H bonds but also two ortho C-H
bonds takes place in the same system.
The total of the bond angles P1-Mo1-P2,
P2-Mo1-P3, P3-Mo1-P4, and P4-Mo1-P1 is 362.2°,
which confirms the planarity of the P-P-Mo-P-P
moiety. A survey of the Cambridge Crystallographic
Database revealed that the Mo1-Ge1 bond distance of
2.587(2) Å lies in the usual region for Mo-Ge single-
bond lengths in molybdenum-germyl complexes
(2.5-2.7 Å). The most intriguing aspect of the structure
of 3 is that the Mo1-P1 bond length (2.456(4) Å) is
nearly equal to that of the Mo1-P2 bond (2.457(5) Å),
indicating that the resultant germanium-carbon link-
ages do not affect these bonds, although P1-Mo1-P4
is slightly compressed (98.8(2)°) and P2-Mo1-P3 is
slightly enlarged (102.0(2)°).
The structure can be compared with that of the
parent complex 113 and the closely related molybde-
num-germanium complex MoH(GeH2Ph)(CO)(Et2PCH2-
CH2PEt2)2 (A).6 The Ge1-C1 bond distance of 2.03(2)
Å is similar to that of 1.998(3) Å in A. On the other
hand, the Mo1-Ge1 bond distance of 2.587(2) Å is
considerably shorter than that of 2.6693(5) Å in A.
Presumably this is due to the chelating constraint
imposed by the P-P-Ge-P-P framework. The
P2-Mo1-P3 bond angle of 102.0(2)° is nearly identical
with that found in 1 (101.56(2)°). In addition, the mean
Mo-P bond length of 2.450 Å in 3 is only slightly longer
than that exhibited by 1 (2.420 Å).
Subsequently, the reactivity of 1 toward a series of
primary silanes was studied. Various kinds of primary
silanes containing ortho-hindered (2b), electron-with-
drawing (2c), electron-donating (2d), and even aliphatic
substituents (2e,f) reacted with 1 to give the corre-
sponding complexes similar to 2. Preparative and
selected spectroscopic data are compiled in Tables 2
and 3.
In 1H NMR, the hydride resonances for the C6F5
compound 2c are shifted to lower field by about 0.2 ppm,
while those for the 4-Me2NC6H4 compound 2d are
shifted to higher field by about 0.05 ppm versus the
corresponding resonances for the phenyl compound 2.
A higher field shift compared to 2 is also observed in
the pair 2e,f. Taking into account the electronic effect
of these substituents, the present results are expected.
At present, the structure of 2 remains somewhat
ambiguous, as no crystals suitable for X-ray diffraction
are available and combustion analyses have been re-
(14) Microanalyses were performed, but none of the products, except
for 2f (Anal. Calcd for C58H60P4MoSi: C, 69.31; H, 6.02. Found: C,
69.56; H, 6.10), could be analyzed properly; carbon percentage values
were found to be approximately 2-4% below their calculated values,
and reproducibility was poor on samples that were clean as determined
by 1H NMR. In silicon compounds, carbon contents are occasionally
too low due to formation of silicon carbide. See: So¨ldner, M.; Sandor,
M.; Schier, A.; Schmidbaur, H. Chem. Ber. 1997, 130, 1671.
(15) Appleton, T. G.; Clark, H. C.; Manzer, L. E. Coord. Chem. Rev.
1973, 10, 335.
(13) Pombeiro, A. J. L.; Hills, A.; Hughes, D. L.; Richards, R. L. Acta
Crystallogr., Sect. C 1995, 23.

Polydentate Phosphinoalkyl-Silyl and -Germyl Ligands
Organometallics, Vol. 24, No. 14, 2005 3437
Table 3. Selected Spectroscopic Data for [MoH3{[Ph2PCH2CH2P(Ph)C6H4-o]2(R)E-P,P,P,P,E}]
1H NMR (J, Hz)
IRa/cm-1
ν(Mo-H)
compd
δ(Mo-H)
δ(other)
31P NMR (J, Hz)
2
1714
1705
1718
-4.45 (br quint, 2H, JHP ) 35)
-4.15 (br t, 1H, JHP ) 33)
1.6-2.6 (m, 8H, C2H4)
81.4 (d, 2P, JPP ) 61)
110.2 (d, 2P, JPP ) 61)
83.6 (d, 2P, JPP ) 58)
112.8 (d, 2P, JPP ) 58)
76.9 (dd, 1P, JPP ) 25, 48)
87.1 (dd, 1P, JPP ) 33, 65)
108.0 (dd, 1P, JPP ) 25, 48)
109.0 (dd, 1P, JPP ) 33, 65)
82.0 (d, 2P, JPP ) 61)
109.0 (d, 2P, JPP ) 61)
82.0 (d, 2P, JPP ) 59)
110.0 (d, 2P, JPP ) 59)
80.4 (d, 2P, JPP ) 61)
110.2 (d, 2P, JPP ) 61)
80.1 (d, 2P, JPP ) 63)
109.5 (d, 2P, JPP ) 63)
83.8 (d, 2P, JPP ) 55)
113.8 (d, 2P, JPP ) 55)
6.6-7.8 (m, 43H, Ph protons)
2a
2b
-4.38 (br quint, 2H, JHP ) 29)
-4.05 (br t, 1H, JHP ) 31)
1.6-2.6 (m, 8H, C2H4), 2.2 (s, 3H, p-CH3-C6H4)
6.6-7.9 (m, 42H, Ph protons)
1.6-2.6 (m, 8H, C2H4), 2.1 (s, 3H, o-CH3-C6H4)
6.6-7.8 (m, 42H, Ph protons)
-4.38 (br quint, 2H, JHP ) 22)
-3.95 (dt. 1H, JHP ) 46, 22)
2c
2d
2e
2f
3
1736
1743
1704
1774
1808
-4.22 (br quint, 2H, JHP ) 27)
-4.03 (br t, 1H, JHP ) 27)
-4.50 (br quint, 2H, JHP ) 27)
-4.20 (br t, 1H, JHP ) 31)
-4.50 (br quint, 2H, JHP ) 24)
-4.40 (br t, 1H, JHP ) 30)
-4.55 (br quint, 2H, JHP ) 25)
-4.45 (br t, 1H, JHP ) 30)
-4.40 (br quint, 2H, JHP ) 29)
-3.90 (br t, 1H, JHP ) 48)
1.6-2.4 (m, 8H, C2H4)
6.6-7.8 (m, 38H, Ph protons)
1.8-2.4 (m, 8H, C2H4), 2.7 (s, 6H, NCH3)
6.8-7.8 (m, 42H, Ph protons)
0.6-1.6 (m, 13H, C6H13), 2.1-2.4 (m, 8H, C2H4)
6.5-7.5 (m, 38H, Ph protons)
0.9-1.9 (m, 11H, C6H11), 2.0-2.5 (m, 8H, C2H4)
6.5-7.5 (m, 38H, Ph protons)
1.6-2.6 (m, 8H, C2H4)
6.6-8.0 (m, 43H, Ph protons)
Table 4. Interatomic Distances (Å) and Angles
(deg) for 4
Scheme 2
Distances
Mo1-P1
Mo1-P3
Si1-Mo1
Si1-C1
2.455(2)
2.451(2)
2.620(2)
1.898(9)
1.913(3)
Mo1-P2
Mo1-P4
Si2-Mo1
Si2-C7
2.490(2)
2.487(2)
2.559(2)
1.899(8)
1.913(8)
Si2-C16
Si2-C46
Angles
P1-Mo1-P2
P1-Mo1-P3
Si1-Mo1-Si2
Mo1-Si2-C7
81.08(7)
101.39(7)
143.91(5)
126.2(2)
P2-Mo1-P4
P3-Mo1-P4
Mo1-Si1-C1
C16-Si2-C46
100.67(7)
79.44(7)
124.4(3)
106.6(3)
The spectroscopic data for 4 are consistent with the
solid-state structure. The high-field 1H NMR spectrum
for 4 is informative; it exhibited a complex multiplet
centered at δ -4.50 ppm and a broad quintet at -5.40
ppm for the Mo-H resonances due to coupling to 31P
nuclei. The integration ratio of the former and the latter
was found to be 1:1. No change was observed for the
signals on lowering the temperature in toluene-d8 to
-60 °C. The presence of two sets of hydride signals of
identical intensities at least at and below room temper-
ature may indicate that these two hydrides are located
separately in both sides of the pseudoequatorial plane
comprised of four phosphorus atoms of the dppe ligands.
The 31P{1H} NMR spectrum of 4 revealed two doublets
at δ 94.1 and at 72.5 ppm with a coupling constant value
of 70 Hz.
does not impose a significant effect upon the equa-
torial plane defined by the four phosphorus atoms. The
Mo1-Si2 bond distance is 2.559(2) Å, which is slightly
shorter than that of the Mo-Ge bond in 3 by ca. 0.03
Å. On the other hand, the mean Mo-P distance of 2.471
Å in 4 is slightly longer than that found in 3 (2.450 Å).
The Si2-C7 bond distance of 1.899(8) Å is shorter than
that of Ge1-C1 in 3 (2.03(2) Å), reflecting a difference
in their covalent radii (Ge ) 1.23 Å and Si ) 1.17 Å).
Reactions of
1 with excess C6F5SiH3 and 4-
Me2NC6H4SiH3 provided the analogous disilyl type
complexes [MoH2(Ar){[Ph2PCH2CH2P(Ph)C6H4-o]2(Ar)-
Si-P,P,P,P,Si}] (Ar ) C6F5 (4a), 4-Me2NC6H4 (4b)). In
contrast to these silanes, treatment of 1 with excess
p-CH3C6H4SiH3, o-CH3C6H4SiH3, and PhGeH3 did not
allow the synthesis of the corresponding disilyl and
digermyl type complexes, due to the highly unstable
nature of the products.
Reaction of 1 with Ph2EH2 in Toluene. When the
secondary silane Ph2SiH2 was employed in a similar
reaction with 1, the trihydride complex 5 with a tri-
dentate P-P-Si ligand was isolated in 87% yield
(Scheme 3).
X-ray-quality crystals of 5 were successfully grown
from a benzene/hexane solution. The molecular struc-
ture is depicted in Figure 3; selected bond distances and
Figure 2. ORTEP drawing of the molecular structure
of 4.

3438 Organometallics, Vol. 24, No. 14, 2005
Minato et al.
Table 6. Comparison of Structural Parameters for
Compounds 1 and 3-5
Mo-P bond
dist, Å
P-Mo-P bond angle, deg
compd
113
3
2.421a
2.450b
2.471b
2.465b
82.30(2)
80.6(2)
101.56(2)
102.0(2)
80.8(2)
98.8(2)
4
81.08(7) 79.44(7) 100.67(7) 101.39(7)
79.1(1) 79.2(2) 100.5(2) 95.4(1)
5
a Mean value of the two Mo-P distances. b Mean value of the
four Mo-P distances.
Scheme 4
Figure 3. ORTEP drawing of the molecular structure
of 5.
Scheme 3
bond between the E atom and the phenyl group has very
little impact on the bond lengths and the angles to the
resulting ligands.
The 31P{1H} NMR spectrum of 5 consisted of four
signals at δ 84.1, 85.1, 91.7, and 109.1 ppm with a 1:1:
1:1 peak area ratio, indicating the presence of four
inequivalent P nuclei, which is fully in accord with the
X-ray diffraction data. At room temperature, the 1H
NMR spectrum of 5 exhibited one broad shielded
resonance at δ -5.20 ppm due to the hydride ligands;
it is analyzed as a doublet of quartets with coupling
constant values of 16 and 29 Hz. This is in stark
contrast to complexes 2 and 4, in which the correspond-
ing hydride ligands were found to be inequivalent at
room temperature. However, at temperatures below -70
°C, three resonances (δ -2.0, -6.3, and -6.7) were
observed in the hydride region, indicating the non-
equivalence of the three hydride groups in 5.
Using methylphenylsilane (PhMeSiH2) as a reagent,
the methylated congener 5a was obtained in 73% yield.
The structural assignment is based upon comparing
spectroscopic data with those for 5 (see Experimental
Section).
Noteworthy is the reaction of 1 with the secondary
species Ph2GeH2, which resulted in the formation of 3
(85% yield). We confirmed that the reaction proceeds
with accompanying evolution of 1 mol of benzene
(Scheme 4).
Table 5. Interatomic Distances (Å) and Angles
(deg) for 5
Distances
Mo1-P1
2.503(4)
2.477(2)
2.541(2)
1.919(7)
1.70(6)
Mo1-P2
2.418(5)
2.460(5)
1.909(6)
1.917(6)
1.76(6)
Mo1-P3
Mo1-P4
Si1-Mo1
Si1-C53
Mo1-H(1Mo)
Mo1-H(3Mo)
Mo1-C48
Si1-C59
Mo1-H(2Mo)
1.72(6)
Angles
P1-Mo1-P2
P1-Mo1-P4
Mo1-Si1-C53
79.2(2)
100.5(2)
121.6(2)
P2-Mo1-P3
P3-Mo1-P4
C48-Si1-C59
95.4(1)
79.1(1)
100.9(3)
angles are listed in Table 5. The structure is well-
resolved, and the hydride atoms are clearly identified.
The ORTEP drawing shows that complex 5 contains a
new bond between the silyl atom and the ortho carbon
of the phenyl group in one of the dppe ligands. Accord-
ingly, even in the case of the secondary silane system,
activation of the Si-H bond and the ortho C-H bond
takes place.
The Mo1-Si1 bond length (2.541(2) Å) is remarkably
similar to that exhibited by 4 (2.559(2) Å). The Mo-P
bond length of 5 (2.465 Å (average)) is also similar to
that of 4 (2.471 Å (average)). The hydrides are located
on both sides of the pseudoequatorial plane comprised
of four phosphorus atoms of the dppe ligands.
To compare the coordination environment of the
molybdenum atom of 5 with those of 1, 3, and 4, Table
6 presents a selected list of structural parameters for
the four compounds. As is evident from the data, these
parameters do not change significantly among the four
structures, indicating that the formation of the new
The result is in contrast to that found in a similar
reaction employing Ph2SiH2, in which the only isolated
product was complex 5, as described above. The reac-
tion between 1 and Ph2GeH2 was found to be very
sensitive to the reaction temperatures. At temperatures
of 100-105 °C, the intermediary 6 with tridentate
ligand, which is analogous to the silyl complex 5, was
formed (96%). We observed that 6 is converted easily
into 3 by heating the former in toluene at 110 °C.
To obtain some insights into the mechanism of the
formation of 3, we attempted the reaction of 1 with
selectively deuterium-labeled (C6D5)2GeH2 at 110 °C

Polydentate Phosphinoalkyl-Silyl and -Germyl Ligands
Organometallics, Vol. 24, No. 14, 2005 3439
Scheme 5
oxidative addition of the ortho C-H bond of the phenyl
group in the dppe ligand to the 16-electron reactive
intermediate MoH2(dppe)2 formed by H2 loss to give the
ortho-metalated species, oxidative addition of RR′SiH2,
reductive elimination to generate a new Si-C bond, and
intramolecular oxidative addition of the Si-H bond. A
similar reaction process in which a coordinatively
unsaturated species is first converted into the ortho-
metalated intermediate through the ortho C-H bond
scission in the dppe ligand was observed by Hidai and
co-workers.20 They reported that the thermal reaction
of trans-[M(N2)2(dppe)2] (M ) Mo, W) with dppe resulted
in the formation of the tetradentate phosphine ligand
o-C6H4(PPhCH2CH2PPh2). One proposed pathway for
this novel transformation involves cleavage of the P-Ph
bond in one dppe ligand and the ortho C-H bond of one
Ph group in the other dppe ligand. Although their
results add weight to the present mechanism, it must
be remembered that, in the reaction between 1 and
Ph2GeH2, intervention of the germylene intermediate
was postulated. Therefore, an analogous path that
includes the intermediacy of silylene metal complexes
via R-migration of hydrogen cannot be ruled out.21 In
an effort to determine which pathway is operative here,
a study with deuterium-labeled Ph2SiD2 was performed
(Scheme 6). If formation of 5 were to proceed via the
ortho-metalated intermediate, two deuterium atoms
would be incorporated in the final product (i), as shown
by path A of Scheme 6. On the other hand, if the silylene
intermediate were involved in the mechanism (path B),
complex i or monodeuterated ii would be obtained,
depending on whether H2 or DH is released. Thus, in
this case, the final product seems to be a 1:2 mixture of
i and ii on the basis of statistical considerations.
Detailed analysis of the reaction product using 1H
NMR revealed that the ratio of the total intensity of
hydrido signals to that of the CH2CH2 signals in the
dppe ligand was found to be 1.00:4.54. When the
reaction proceeds via the silylene pathway to yield a 1:2
mixture of i and ii, this ratio would be 1.00:4.80.
Therefore, we favor the silylene mechanism as a plau-
sible explanation of the present system. Presumably, in
the case of the primary silane RSiH3, the process repeats
to attach Si to the phenyl group in the other dppe ligand
to give the final products 2.
(Scheme 5). It was hoped that this reagent could be used
to determine whether the resulting benzene is derived
from the phenyl group in the dppe ligand16 or from the
phenyl group in diphenylgermane.
GC-MS analysis of the volatile products showed a
peak at m/z 83, which was ascribed to pentadeuterated
benzene, C6D5H, suggesting a cleavage of the Ge-C(Ph)
bond. This R-elimination reaction of 1 with Ph2GeH2 is
proposed to occur via intervention of the germylene
intermediate. The silyl complex 5 was found to be stable
to prolonged heating in toluene; similar transformation
into 2 did not take place at all. It is quite difficult to
rationalize these differences in the reactivity between
Ph2GeH2 and Ph2SiH2, because the strengths of chemi-
cal bonds in Ge-C(Ph) and Si-C(Ph) are similar.17 In
organogermanium compounds, intramolecular coordina-
tion between a germanium atom and a substituent
(halogen, O, S, etc.) in a position R to the germanium
has been known to favor a homolytic cleavage of the
Ge-C bond.18 Hence, the Mo(dπ)-GeC(Ph)(σ*) interac-
tion might have induced a weakening of the Ge-C bond.
In the case of the silyl-molybdenum complex 5, we may
suppose that such an interaction between the d electron
and antibonding orbital is weak, since the Si-C(σ*)
orbital lies much higher in energy than the Ge-C(σ*)
orbital. Similar reaction patterns in which a germyl-
metal complex suffers Ge-C bond cleavage by R-migra-
tion whereas the corresponding silyl-metal complex
does not have been observed for ruthenium systems of
the type L3Ru-ER3.19 However, to the best of our
knowledge, the present results show the first example
for the molybdenum system.
Consideration of the Formation Mechanism of
the Complexes 2 and 5. The reaction is a very complex
one, where Mo-H, Si-H, and C-H bond cleavage/
formation all occurs in the same system. There are two
possible mechanisms.9a The most plausible is a route
that incorporates a sequence of reactions involving
Conclusion
Reaction of [MoH4(dppe)2] (1) with a series of pri-
mary silanes and germanes REH3 in refluxing toluene
yielded the novel complexes [MoH3{[Ph2PCH2CH2P(Ph)-
C6H4-o]2(R)E-P,P,P,P,E}] (E ) Si (2), Ge (3)) with a
quinquidentate ligand comprised of a P-P-E-P-P
framework. Despite the difference in the electronic prop-
erties and the steric requirements of the starting silanes
and germanes, the resulting complexes exhibit similar
structural features, as determined by NMR spectros-
copy. When the secondary silane Ph2SiH2 was employed
in a similar reaction with 1, the trihydrido complex 5
with a tridentate ligand ([Ph2PCH2CH2P(Ph)C6H4-o]-
Ph2Si-P,P,Si) comprised of a P-P-Si framework was
(16) Hidai and co-workers reported that thermal reaction of the
related molybdenum N2 complex trans-[Mo(N2)2(dppe)2] resulted in
condensation of two dppe ligands with concurrent liberation of benzene;
see: Arita, C.; Seino, H.; Mizobe, Y.; Hidai, M. Bull. Chem. Soc. Jpn.
2001, 74, 561.
(17) Pilcher, G.; Skinner, H. A. In The Chemistry of the Metal-Carbon
Bond; Hartley, F. R., Patai, S., Eds.; Wiley: Chichester, U.K., 1982;
Vol. 1 (The Structure, Preparation, Thermochemistry, and Character-
ization of Organometallic Compounds), p 43.
(18) Riviere, P.; Riviere-Baudet, M.; Stage´, J. In Comprehensive
Organometallic Chemistry; Wilkinson, G., Stone, F. G. A., Abel, E. W.,
Eds.; Pergamon Press: Oxford, U.K., 1982; Vol. 2, p 399.
(19) (a) Reichl, J. A.; Popoff, C. M.; Gallagher, L. A.; Remsen, E. E.;
Berry, D. H. J. Am. Chem. Soc. 1996, 118, 9430. (b) Katz, S. M.; Reichl,
J. A.; Berry, D. H. J. Am. Chem. Soc. 1998, 120, 9844. (c) Dioumaev,
V. K.; Plo¨ssl, K.; Carroll, P. J.; Berry, D. H. J. Am. Chem. Soc. 1999,
121, 8391.
(20) Arita, C.; Seino, H.; Mizobe, Y.; Hidai, M. Chem. Lett. 1999,
611.
(21) Feldman, J. D.; Peters, J. C.; Tilley, T. D. Organometallics 2002,
21, 4065.

3440 Organometallics, Vol. 24, No. 14, 2005
Minato et al.
Scheme 6
recorded on a JEOL-JNM-270 spectrometer. 31P{1H} NMR
peak positions were referenced to external H3PO4 or PPh3.
isolated. On the other hand, the reaction between
Ph2GeH2 and 1 proceeded with accompanying evolution
of 1 mol of benzene to give 3. We have observed evidence
to suggest that the reaction path includes the interme-
diacy of silylene or germylene metal complexes via an
R-migration process. We believe that these new com-
plexes possess rich reaction chemistry. The properties
of the complexes and a range of further reactions are
currently being investigated in our laboratory.
X-ray Crystallography. Single crystals were mounted on
a Rigaku AFC7R four-circle diffractometer equipped with
graphite-monochromated Mo KR radiation and a rotating
anode generator. All diffraction studies were performed at 23
°C. The parameters used during the collection of diffraction
data are given in Table 7. The non-hydrogen atoms were
refined anisotropically. Hydrogen atoms were included but not
refined.
Reaction of 1 with 1 Equiv of Primary Silanes and
Germanes in Toluene. A solution of 1 (1.153 g, 1.286 mmol)
and phenylsilane (160 µl, 1.286 mmol) in toluene (90 mL) was
heated with stirring at 110 °C for 3 h. The solution was
initially yellow but gradually darkened to brown. The resulting
solution was concentrated to a volume of 45 mL under reduced
pressure. Hexane (25 mL) was then added, and the mixture
was allowed to stand for 12 h at 0 °C, whereupon yellow
precipitates separated. The product was collected by filtration,
washed with hexane (10 mL × 3), and then dried in vacuo to
give 2 (0.858 g, 66%). This procedure is also applicable to the
synthesis of the other complexes (2a-f and 3). Experiments
listed in Table 2 were carried out under essentially the same
conditions. A crystal of 3 suitable for X-ray crystallographic
analysis could be obtained by recrystallization from toluene/
hexane solution.
Experimental Section
General Procedures and Reagent Syntheses. Unless
otherwise noted, all manipulations were performed using
standard Schlenk techniques under purified argon or nitrogen.
Commercially available reagent grade chemicals were used as
such without any further purification. All solvents were dried
by standard methods and were stored under argon. Complex
1, organosilanes, and organogermanes were prepared by
literature procedures or modifications of these.7,22 Selectively
deuterium-labeled (C6D5)2GeH2 was prepared by reduction of
(C6D5)2GeCl2 (prepared from C6D5MgBr and GeCl4) with
LiAlH4 by a standard method.23 Ph2SiD2 was prepared by
reaction of Ph2SiCl2 with LiAlD4. All NMR spectra were
(22) (a) Molander, G. A.; Corrette, C. P. Organometallics 1998, 17,
5504. (b) Benkeser, R. A.; Landesman, H.; Foster, D. J. J. Am. Chem.
Soc. 1952, 74, 648.
(23) El-Maradny, A.; Tobita, H.; Ogino, H. Organometallics 1996,
15, 4954.
Reaction of 1 with Excess ArSiH3 in Toluene. A solution
of 1 (0.208 g, 0.232 mmol) and phenylsilane (173 µl, 1.39 mmol)
in toluene (20 mL) was heated with stirring at 110 °C for 3 h.

Polydentate Phosphinoalkyl-Silyl and -Germyl Ligands
Table 7. Crystal Data for Complexes 3-5
Organometallics, Vol. 24, No. 14, 2005 3441
washed with hexane (5 mL × 3), and then dried in vacuo to
give 5 (0.239 g, 87%). A yellow crystal suitable for X-ray
crystallographic analysis could be obtained by recrystallization
from benzene/hexane solution. A similar experiment employing
PhMeSiH2 gave 5a in 70% yield.
3
4
5
chem formula
fw
C58H54GeMoP4 C78H74MoP4Si2 C64H60MoP4Si
1043.49
monoclinic
Pn (No. 7)
2
12.465(3)
12.111(3)
16.631(6)
94.90(3)
2501(1)
1072.00
1287.45
1077.10
cryst syst
space group
Z
orthorhombic monoclinic
1
5. H NMR (C6D6, ppm): 1.6-2.6 (br, 8H, C2H4), -5.20 (d
Pbca (No. 61) P21/n (No. 14)
quart, 3H, JHP ) 16, 29 Hz, MoH3). 31P NMR (THF-d8, ppm):
109.1 (m, 1P), 91.7 (m, 1P), 85.1 (m, 1P), 84.1 (m, 1P). IR
(KBr): ν(Mo-H) 1732 cm-1. Anal. Calcd for C64H60MoSiP4: C,
71.37; H, 5.62. Found: C, 70.68; H, 5.49.
8
4
a, Å
44.862(5)
23.072(4)
12.859(5)
10.07(1)
23.07(1)
23.06(2)
93.0(2)
5351(6)
2240.00
1.337
b, Å
c, Å
â, deg
1
5a. H NMR (THF-d8, ppm): 1.6-2.6 (br, 8H, C2H4), 0.43
V, Å3
13309(4)
5376.00
1.285
(s, 3H, SiCH3), -4.80 (d quart, JHP ) 16, 29 Hz, 3H, MoH3).
F(000)
31P NMR (THF-d8, ppm): 115.8 (m, 1P), 92.6 (m, 3P). IR
d(calcd), g cm-3 1.385
(KBr): ν(Mo-H) 1714 cm-1
.
µ(Mo KR), cm-1 10.16
3.72
4.27
Reaction of 1 with Ph2GeH2 in Toluene. A solution of 1
(1.09 g, 1.220 mmol) and Ph2GeH2 (359 µl, 1.820 mmol) in
toluene (100 mL) was heated with stirring at 110 °C for 6 h.
The solution was initially yellow but gradually darkened to
brown. The resulting solution was concentrated to a volume
of 50 mL under reduced pressure. Hexane (50 mL) was then
added, and the mixture was allowed to stand for 12 h at 0 °C,
whereupon yellow precipitates separated. The product was
collected by filtration, washed with hexane (10 mL × 3), and
then dried in vacuo to give 3 (1.08 g, 85%). In this reaction,
GC analysis of the volatiles revealed the formation of ben-
zene (83%, based on 1). A similar experiment employing
(C6D5)2GeH2 gave C6D5H, which was identified by GC-MS
spectrometry (EI, 70 eV).
cryst size, mm 0.35 × 0.20 × 0.30 × 0.24 × 0.30 × 0.25 ×
0.02
0.24
0.20
20 (29.9-30.6)
32, 16, 8,4
2θ range, deg
scan rate,
deg min-1
no. of rflns
measd
no. of unique
rflns
no. of rflns
obsd
R
Rw
GOF
22 (28.7-29.9) 23.34-29.36
16.0
16.0
6368
6024
2863
9544
9542
4646
0
12 606
7286
(I > 3σ(I))
0.053
0.083
1.31
(I > 2σ(I))
(I > 3σ(I))
0.082
0.246
1.34
0.045
0.047
1.47
The solution was initially yellow but gradually darkened to
brown. The resulting solution was concentrated to a volume
of 10 mL under reduced pressure. Hexane (20 mL) was then
added, and the mixture was allowed to stand for 12 h at 0 °C,
whereupon yellow crystals in the form of flat plates suitable
for X-ray crystallographic analysis separated. The product
was collected by filtration and then dried in vacuo to give 4
(0.233 g, 78%). Similar experiments employing C6F5SiH3 and
4-Me2NC6H4SiH3 gave 4a (81%) and 4b (89%), respectively.
When the reaction was conducted at temperatures of
100-105 °C, complex 6, which is analogous to the silyl complex
5, was formed (96%).
1
6. H NMR (C6D6, ppm): 1.5-2.7 (br, 8H, C2H4), -4.30 (br
quint, 3H, MoH3). 31P NMR (C6D6, ppm): 115.5 (br d, 1P, JPP
) 46 Hz), 94.2 (m, 1P), 76.9 (m, 2P). IR (KBr): ν(Mo-H) 1812
cm-1
.
Acknowledgment. We are grateful to Prof. K.
Osakada of the Tokyo Institute of Technology, Dr. M.
Yamasaki of Rigaku Corp., and Dr. Y. Yamaguchi of
Yokohama National University for X-ray structure
analyses. We also thank Prof. K. Mochida of Gakushuin
University for a generous gift of GeCl4. We gratefully
acknowledge Dr. T. Koizumi of the Tokyo Institute of
Technology for T1 measurements and for helpful discus-
sion. We wish to thank Dr. M. Tanaka of the Tokyo
Institute of Technology and Dr. T. Fujiwara and Profes-
sor A. Nagasawa of Saitama University for the elemen-
tal analyses.
1
4. H NMR (C6D6, ppm): 4.20 (s, 2H, SiH2), -4.50 (br m,
1H, MoH), -5.40 (br quint, 1H, MoH). 31P NMR (THF-d8,
ppm): 94.1 (br d, 2P, JPP ) 70 Hz), 72.5 (br d, 2P, JPP ) 70
Hz). IR (KBr): ν(Si-H) 2083 cm-1, ν(Mo-H) 1742 cm-1. Anal.
Calcd for C78H76P4MoSi2 (4‚2(toluene)): C, 72.65; H, 5.94.
Found: C, 72.85; H, 5.93.
4a. 1H NMR (C6D6, ppm): 6.0-8.0 (m, 38H, Ph protons),
3.9-4.0 (br, 2H, SiH2), 1.6-2.8 (br, 8H, C2H4), -4.10 (br m,
1H, MoH), -5.20 (br m, 1H, MoH). 31P NMR (C6D6, ppm):
102.0 (br d, 2P, JPP ) 63 Hz), 71.0 (br d, 2P, JPP ) 63 Hz). IR
(KBr): ν(Si-H) 2142 cm-1, ν(Mo-H) 1711 cm-1
.
4b. 1H NMR (C6D6, ppm): 6.0-8.0 (m, 46H, Ph protons),
3.9-4.0 (br, 2H, SiH2), 2.8 (br, 12H, NCH3), 1.8-2.8 (br, 8H,
C2H4), -4.10 (br m, 1H, MoH), -5.30 (br m, 1H, MoH). 31P
NMR (C6D6, ppm): 100.0 (br d, 2P, JPP ) 71 Hz), 79.0 (br d,
2P, JPP ) 71 Hz). IR (KBr): ν(Si-H) 2132 cm-1, ν(Mo-H) 1712
Supporting Information Available: Listings of atomic
coordinates, anisotropic thermal parameters, and extensive
interatomic distances and angles for 5. This material is
available free of charge via the Internet at http://pubs.acs.org.
This data and the data for 3, 4 have also been deposited with
the Cambridge Crystallographic Data Centre, as CCDC Nos.
270366, 183312, and 100496, respectively. Copies of this
information may be obtained free of charge from The Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ, U.K. (fax,
+44-1223-336033; e-mail, deposit@ccdc.cam.ac.uk; web,
http://www.ccdc.cam.ac.uk).
cm-1
.
Reaction of 1 with PhRSiH2 in Toluene. A solution of 1
(0.229 g, 0.255 mmol) and Ph2SiH2 (283 µl, 1.53 mmol) in
toluene (20 mL) was heated with stirring at 110 °C for 5 h.
The solution was initially yellow but gradually darkened to
brown. The resulting solution was concentrated to dryness,
and the crude product was extracted with benzene (10 mL).
Hexane (25 mL) was then added, and the mixture was allowed
to stand for 12 h at room temperature, whereupon yellow
precipitates separated. The product was collected by filtration,
OM0401298