Syntheses of di- and trinuclear platinum complexes with multibridged germanium centers derived from unsymmetrical digermanes

Article abstract of DOI:10.1021/om3007147

A trigonal-bipyramidal Pt₃Ge₂ cluster was synthesized by the reaction of the zerovalent platinum complex [Pt(dppe)(η²- C₂H₄)] (dppe = 1,2-bis(diphenylphosphino)ethane) with the unsymmetrical digermane H₃GeGeEt₃ at a 3/2 molar ratio. The platinum centers formed a triangular plane bridged by two germylyne ligands, one of which maintained the Ge-Ge bond. To investigate the Pt ₃Ge₂ cluster formation process, the phenyl-substituted digermanes HPh₂GeGeMe₃ and H₂PhGeGeR ₃ (R = Me, Et), in which two hydrogen atoms and one hydrogen atoms of the reactive GeH₃ moiety were replaced by the bulkier phenyl group(s) together with the substitution of the GeEt₃ group by a GeMe₃ group, respectively, were used to simplify the reaction system. They provided the digermylplatinum hydride [Pt(dppe)(H)(GePh ₂GeMe₃)] (2) and the bis(μ-germylene)diplatinum complexes [Pt₂(dppe)₂(μ-GeHPh)(μ-Ge(Ph)GeR ₃)] (3, R = Me; 4, R = Et) in moderate yields, respectively. For 3 and 4, the first-formed digermylplatinum hydride I-1 underwent dissociation of one of the phosphorus donors followed by 1,2-germyl migration to give the corresponding bis(germyl)platinum complex I-2, as observed in the previously reported silicon system. On the one hand, the germyl migration did not take place in the case of 2, owing the Ge-Ge bond being less reactive than the Si-Si bond. Intermediates I-1 and I-2 coupled to each other to afford the germylene-bridged diplatinum complexes 3 and 4 accompanied by extrusion of H₂ and R₃GeH. In the case of H₃GeGeEt ₃, the corresponding bis(μ-germylene)diplatinum complex reacted with [Pt(dppe)(η²-C₂H₄)], resulting in the formation of the desired Pt₃Ge₂ cluster. The spiro-type Pt₄Ge complex was obtained only by changing mole equivalents of [Pt(dppe)(η²-C₂H₄)], demonstrating the usefulness of the present method using H₃GeGeEt₃, which can readily regulate the molar ratio.

Full text of DOI:10.1021/om3007147

Article
pubs.acs.org/Organometallics
Syntheses of Di- and Trinuclear Platinum Complexes with
Multibridged Germanium Centers Derived from Unsymmetrical
Digermanes
Hidekazu Arii, Rei Hashimoto, Kunio Mochida,* and Takayuki Kawashima
Department of Chemistry, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo 171-8588, Japan
S
* Supporting Information
ABSTRACT: A trigonal-bipyramidal Pt3Ge2 cluster was
synthesized by the reaction of the zerovalent platinum complex
[Pt(dppe)(η2-C2H4)] (dppe = 1,2-bis(diphenylphosphino)-
ethane) with the unsymmetrical digermane H3GeGeEt3 at a 3/
2 molar ratio. The platinum centers formed a triangular plane
bridged by two germylyne ligands, one of which maintained
the Ge−Ge bond. To investigate the Pt3Ge2 cluster formation process, the phenyl-substituted digermanes HPh2GeGeMe3 and
H2PhGeGeR3 (R = Me, Et), in which two hydrogen atoms and one hydrogen atoms of the reactive GeH3 moiety were replaced
by the bulkier phenyl group(s) together with the substitution of the GeEt3 group by a GeMe3 group, respectively, were used to
simplify the reaction system. They provided the digermylplatinum hydride [Pt(dppe)(H)(GePh2GeMe3)] (2) and the bis(μ-
germylene)diplatinum complexes [Pt2(dppe)2(μ-GeHPh)(μ-Ge(Ph)GeR3)] (3, R = Me; 4, R = Et) in moderate yields,
respectively. For 3 and 4, the first-formed digermylplatinum hydride I-1 underwent dissociation of one of the phosphorus donors
followed by 1,2-germyl migration to give the corresponding bis(germyl)platinum complex I-2, as observed in the previously
reported silicon system. On the one hand, the germyl migration did not take place in the case of 2, owing the Ge−Ge bond being
less reactive than the Si−Si bond. Intermediates I-1 and I-2 coupled to each other to afford the germylene-bridged diplatinum
complexes 3 and 4 accompanied by extrusion of H2 and R3GeH. In the case of H3GeGeEt3, the corresponding bis(μ-
germylene)diplatinum complex reacted with [Pt(dppe)(η2-C2H4)], resulting in the formation of the desired Pt3Ge2 cluster. The
spiro-type Pt4Ge complex was obtained only by changing mole equivalents of [Pt(dppe)(η2-C2H4)], demonstrating the
usefulness of the present method using H3GeGeEt3, which can readily regulate the molar ratio.
without a Ge−C bond is impractical, as it is difficult to regulate
the stoichiometry upon oxidative addition to a transition metal.
Clusters consisting of group 10 transition metals and
germanium atoms are limited to the planar trinuclear palladium
cluster [Pd4(dmpe)3(μ-GePh2)3] (dmpe = 1,2-bis-
(dimethylphosphino)ethane),9 in contrast with the silicon
derivatives,10−12 which are attributed to poor methods of
introducing a bridged-germanium donor into metal clusters.
Recently, we have developed a procedure to synthesize
platinum clusters containing silylyne ligands by using unsym-
metrical disilanes.13 The formation process is described as
follows: (i) oxidative addition of Si−H in disilane, (ii) 1,2-silyl
migration on the platinum center, (iii) dimerization of the
bis(silyl)platinum complex and subsequent reductive elimi-
nation of trialkylsilane, and (iv) addition of another platinum
species. Application of this method to germanium analogues
may induce the production of germanium-containing clusters.
In this study, we prepared a platinum−germanium cluster
and investigated the reaction of the zerovalent platinum
complex [Pt(dppe)(C2H4)] (1; dppe = 1,2-bis-
(diphenylphosphino)ethane) with the unsymmetrical diger-
manes HnPh3−nGeGeR3 (R = Me, Et; n = 1−3). Moreover, the
INTRODUCTION
■
Transition-metal clusters containing main-group elements play
an important role in catalyzing various reactions in artificial
systems as well as in the active site of metalloproteins.1,2
A
metal−metal bond and a metal−metal interaction through a
main-group element in clusters function differently from those
of mononuclear transition-metal species. Transition-metal
clusters that consist of a heavier main-group element are
classified as heterobimetallic clusters and are expected to have
unique physiological properties.3 Among the heavier group 14
elements, germanium and tin are well-known as modifiers of
heterogeneous catalytic systems, and transition-metal clusters
containing these elements have been synthesized and have been
shown to possess catalytic activity.4 Adams and co-workers have
reported that the ruthenium−tin cluster [Ru4(μ4-
SnPh)2(CO)12] fixed on mesoporous silica catalyzes the
hydrogenation of olefins.5
Transition-metal−germanium clusters have been achieved by
the reaction of a low-valent transition-metal complex with a
monogermane (R3−nGeHn; n = 1−3)6,7 or a digermane,
(C5Me4H)Me2GeGeMe2(C5Me4H).8 Since the reaction re-
quires the scission of inactive Ge−C bonds, the transition-metal
center is restricted to elements from groups 8 and 9, which
have the high bond activation abilities necessary for oxidative
addition to the Ge−C bond. Use of the germane gas GeH4
Received: July 27, 2012
Published: September 10, 2012
© 2012 American Chemical Society
6635
dx.doi.org/10.1021/om3007147 | Organometallics 2012, 31, 6635−6641

Organometallics
Article
process of the unusual dephenylation of H2PhGeGeEt3 with
trifluoroacetic acid (CF3CO2H) was studied.
RESULTS AND DISCUSSION
■
Preparation of H3GeGeEt3. The dephenylation of a
phenyl-substituted germane using a common strong Brønsted
acid is one of the most popular methods to obtain a precursor
that can be converted to the corresponding hydrogermane by
hydrogenation.14 The HCl/AlCl3 system cannot control the
number of eliminated phenyl groups, affording a mixture of the
starting material and several dephenylated products. As an
alternative method, a relatively weak organic acid such as
CX3CO2H (X = F, Cl) provides stoichiometric dephenylation
of the germanium atom.15 During the exploration of a reaction
system suitable for dephenylation of H2PhGeGeEt3 to obtain
H3GeGeEt3, we unexpectedly noticed that treatment of
H2PhGeGeEt3 with CF3CO2H in CH2Cl2 directly generated
the desired product H3GeGeEt3 in 18% yield without a hydride
source such as LiAlH4. A combination of other acids
(CF3SO3H and p-toluenesulfonic acid) and solvents (toluene
and CHCl3) led to recovery of the starting material or
formation of a complicated mixture of several compounds. By
Figure 1. Crystal structure of 2, showing 50% probability thermal
ellipsoids. The hydrogen atoms except for H(1h) are omitted for
clarity. Selected bond lengths (A) and angles (deg): Pt(1)−P(1) =
2.2881(6), Pt(1)−P(2) = 2.2785(7), Pt(1)−Ge(1) = 2.4325(3),
Pt(1)-H(1h) = 1.63(3), Ge(1)−Ge(2) = 2.4386(4); P(1)−Pt(1)−
P(2) = 86.17(2), P(1)−Pt(1)−Ge(1) = 100.740(18), P(1)−Pt(1)−
H(1h) = 179.2(10), P(2)−Pt(1)−Ge(1) = 169.711(17), P(2)−
Pt(1)−H(1h) = 93.1(9), Ge(1)−Pt(1)−H(1h) = 80.0(9).
1
monitoring the dephenylation with H NMR spectroscopy, no
conversion of the starting material was observed after addition
of the first dose of CF3CO2H. After the second dose of
CF3CO2H was added, the H NMR spectrum of the reaction
bond alignment was perpendicular to the platinum coordina-
tion plane to prevent steric repulsion between the trimethyl-
germyl group and one of the diphenylphosphino donors. The
1H NMR spectrum of 2 in C6D6 showed the Pt−H signal as a
doublet of doublets at −0.21 ppm, diagnostic of platinum
hydride bearing the supporting ligand dppe,18 although it
resonated at a magnetic field lower than the typical Pt−H
region (−5 to −1 ppm).17b,19 The 31P NMR spectrum
exhibited two resonances at 55.4 (1JPtP = 2033 Hz) and 59.3
ppm (1JPtP = 1996 Hz) flanked with 195Pt satellites assignable to
the two inequivalent phosphorus atoms trans to the digermyl
1
mixture exhibited H3GeGeEt3 formation accompanied by an
unidentified product with a broad signal around 1.0−1.2 ppm,
which disappeared upon LiAlH4 treatment followed by
concentration.16 Use of CF3CO2D in CD2Cl2 produced
deuterated benzene and undeuterated product H3GeGeEt3,
indicating that the hydrogen atom of H3GeGeEt3 did not
originate from the acid or the solvent. We presume that
dephenylation of H2PhGeGeEt3, giving H2(CF3COO)-
GeGeEt3, followed by its disproportionation results in the
formation of H3GeGeEt3 and H(CF3CO2)2GeGeEt3, the latter
of which seems to decompose rapidly, because LiAlH4
treatment did not increase the yield of H3GeGeEt3 after the
second dose of CF3CO2H.16 For the scope of substrates,
however, this method could not be applied to the direct
hydrogenation of other phenyl-substituted monogermanes
(Ph3GeH, Ph2GeH2) and digermanes (HPh2GeGeEt3,
Ph3GeGeEt3).
1
ligand and the hydride, respectively. The two near JPtP values
correlated with the Pt−P bond length results. In comparison
with silicon analogues,20 the larger coupling constant JPtP and
1
the shorter Pt−P bond length associated with the germanium
donor illustrated, as expected, the weaker trans influence of the
digermyl ligand.
Complex 2 did not change even at 110 °C in toluene-d8,
because of its high thermal stability. In fact, the trimethylgermyl
group behaved as an inert substituent. The secondary germane
Mes2GeH2 (Mes = 2,4,6-trimethylphenyl)17b and the sterically
encumbered primary germane TripGeH3 (Trip = 9-tripty-
cyl)17d were reacted with the zerovalent platinum complex
[Pt(PPh3)2(η2-C2H4)] to afford the corresponding germylpla-
tinum hydrides stable at room temperature. Meanwhile, use of
Reaction with HPh2GeGeMe3. The reaction of 1 with
HPh2GeGeMe3 in toluene at room temperature afforded the
digermylplatinum hydride [Pt(dppe)(H)(GePh2GeMe3)] (2)
in 39% yield by the oxidative addition of the Ge−H bond to the
platinum center (Scheme 1). Using X-ray diffraction analysis
21
17c
Scheme 1. Reaction of 1 with HPh2GeGeMe3
the sterically less hindered Ph2GeH2 and MesGeH3
generated the germyl-bridged diplatinum complexes in the
presence of the same platinum complex [Pt(PPh3)2(η2-C2H4)].
Digermane HPh2GeGeMe3 was employed like a bulky tertiary
germane because the trimethylgermyl group did not migrate to
the platinum center, in contrast to the disilane system.17 These
insights suggest that the sterically less hindered digermanes
H2PhGeGeR3 (R = Me, Et) and H3GeGeEt3, due to the
decreased number of phenyl groups on the germanium atom,
were required to prepare a multinuclear platinum−germyl
cluster.
(XRD), it was determined that the platinum center in 2 had
four-coordinate square-planar geometry with a GeP2H donor
set (Figure 1), and the two Pt−P and Pt−Ge bond lengths
were similar to those reported previously.17 The similarity of
the two Pt−P bond lengths means that the trans influence of a
digermyl ligand was close to that of a hydride. The Ge−Ge
Reaction with H2PhGeGeR3. The reactions of 1 with
H2PhGeGeR3 in toluene at room temperature afforded the
bis(μ-germylene)diplatinum complexes [Pt2(dppe)2(μ-
6636
dx.doi.org/10.1021/om3007147 | Organometallics 2012, 31, 6635−6641

Organometallics
Article
GeHPh)(μ-Ge(Ph)GeR3)] (R = Me (3), Et (4)) in 42% and
29% yields, respectively (Scheme 2), accompanied by extrusion
Scheme 2. Reaction of 1 with H2PhGeGeR3
22
1
of H2 and R3GeH detected by H NMR experiments. The
crystal structures of 3 and 4 showed a Pt2Ge2 core with a
rhombus framework in which a mirror plane existed on the
Ge−Ge alignment. No differences between 3 and 4 were
observed. These complexes revealed that the two platinum
centers had a four-coordinate square-planar geometry with a
Ge2P2 donor set and were bridged by different germylenes: that
is, a germylphenylgermylene and hydrophenylgermylene
(Figure 2). The coordination plane of the platinum atom was
disordered, as shown by the slightly large dihedral angle of
16.06(2)° for 3 and 22.10(2)° for 4, as defined by the P−Pt−P
and the Ge−Pt−Ge planes, since one of the diphenylphosphino
groups in dppe prevented steric repulsion to the trialkylgermyl
group on the Ge(Ph)GeR3 ligand. The Pt−Ge and Pt−P bond
lengths were within the typical range of the corresponding
single bonds. The Pt(1)···Pt(1)* and Ge(1)···Ge(3) atomic
distances were much longer than the diagnostic Pt−Pt and
Ge−Ge single bonds,23 respectively, indicating much weaker
interaction between the atoms. By the DFT calculation
reported by Sakaki et al., the model complex
[Pt2(dipe)2(Ge2H4)] (dipe = 1,2-diphosphinoethane) repre-
sented a completely cleavage of the Ge−Ge bond and a
formation of the Pt−Ge covalent bond to be characterized a
bis(μ-germylene)diplatinum complex.24 In addition, it was
found that the two phenyl groups on the germylene ligands
were oriented cis to each other.
Complexes 3 and 4 are rare examples of metal centers
bridged by two different germylenes as well as a bis(μ-
germylene)platinum species, in contrast with many reports of
analogous bis(μ-silylene)diplatinum complexes, which have
been synthesized by dimerization of a monomeric bis(silyl)
platinum or silyl platinum hydride.25,26 In contrast, the
monomeric bis(germyl)platinum complex bearing the bis-
(diphenylphosphino)ethane (dppe) ligand involves Ge−Ge
bond formation by 1,2-germyl migration on the platinum
center to convert to the digermylplatinum hydride reported by
Ishii and co-workers.17d The Braddock-Wilking and Osakada
groups, independently, have reported secondary germane
oligomerization on the platinum center to afford the
platinagermacycle consisting of the formed tetragermane.26
The behavior suggests that 1,2-germyl migration for Ge−Ge
bond activation is not thermodynamically favored and depends
on the coordination sphere of the platinum center. Therefore,
the formation of 3 and 4 was interpreted as follows: the
digermylplatinum hydride I-1 afforded by the Ge−H oxidative
Figure 2. Crystal structures of 3 (top) and 4 (bottom), showing 50%
probability thermal ellipsoids. The hydrogen atoms, except for that on
Ge(3), are omitted for clarity. Selected bond lengths (A) and angles
(deg) for 3: Pt(1)−P(1) = 2.2939(10), Pt(1)−P(2) = 2.2859(10),
Pt(1)−Ge(1) = 2.4786(4), Pt(1)−Ge(3) = 2.4612(4); P(1)−Pt(1)−
P(2) = 85.95(4), Ge(1)−Pt(1)−Ge(3) = 69.744(17), Pt(1)−Ge(1)−
Pt(1)* = 109.61(2), Pt(1)−Ge(3)−Pt(1)* = 110.76(2). Selected
bond lengths (A) and angles (deg) for 4: Pt(1)−P(1) = 2.3092(9),
Pt(1)−P(2) = 2.2700(9), Pt(1)−Ge(1) = 2.4875(4), Pt(1)−Ge(3) =
2.4486(4); P(1)−Pt(1)−P(2) = 85.83(4), Ge(1)−Pt(1)−Ge(3) =
69.188(16), Pt(1)−Ge(1)−Pt(1)* = 109.50(2), Pt(1)−Ge(3)−
Pt(1)* = 112.12(2).
addition of H2PhGeGeR3 to the platinum atom in 1 was
converted to the bis(germyl)platinum intermediate I-2 by slow
1,2-germyl migration; the intermediates I-1 and I-2 coupled to
each other to afford the diplatinum complexes bridged by the
germylene ligand, which maintains a Ge−Ge bond.28
1
The H NMR spectra of 3 and 4 in C6D6 exhibited the
unsymmetrical ethylene linker and phenyl groups in dppe, and
the signals assignable to Ge−H were observed as multiplets at
3.7−4.0 and 3.5−3.8 ppm, respectively, which were shifted to a
higher magnetic field relative to that of H2PhGeGeR3 (R = Me,
4.40 ppm; R = Et, 4.42 ppm). The 31P NMR spectra of 3 and 4
in C6D6 showed two inequivalent phosphorus atoms as a
doublet of doublets flanked with 195Pt satellites at 56.7/58.0
and 55.2/57.6 ppm, respectively. The other phosphorus
resonance was also observed as a singlet at 57.1 ppm, despite
the use of a recrystallized sample of 3,29 which was associated
with the bis(μ-germylene)diplatinum complex [Pt(dppe)(μ-
GeHPh)]2 bridged by the same two germylene ligands. The
trimethylgermyl group in I-1 (R = Me) took advantage of the
1,2-germyl migration, which enhanced the formation of I-2
followed by homodimerization to produce [Pt(dppe)(μ-
6637
dx.doi.org/10.1021/om3007147 | Organometallics 2012, 31, 6635−6641

Organometallics
Article
GeHPh)]2. Unfortunately, complexes 3 and 4 did not
transform into a higher dimensional cluster, regardless of the
addition of 1.
Table 1. Selected Bond Lengths (Å) and Angles (deg) of 5
Bond Lengths (Å)
Pt(1)−P(1)
Pt(1)−P(2)
Pt(1)−Ge(1)
Pt(1)−Ge(3)
Pt(2)−P(3)
Pt(2)−P(4)
Pt(2)−Ge(1)
2.2512(12)
2.2414(12)
2.4897(6)
2.4220(6)
2.2577(13)
2.2400(13)
2.4918(5)
Pt(2)−Ge(3)
Pt(3)−P(5)
Pt(3)−P(6)
Pt(3)−Ge(1)
Pt(3)−Ge(2)
Ge(1)−Ge(2)
Ge(1)−Ge(3)
2.4183(6)
2.2503(13)
2.2487(12)
2.4902(6)
2.4226 (6)
2.4307(7)
2.8172(7)
Reaction with H3GeGeEt3. The isolated digermane
H3GeGeEt3 is a liquid at room temperature; therefore, it is
suitable to use for a stoichiometric reaction, in sharp contrast
with GeH4 and MeGeH3, which are gases at room temperature.
We tried to synthesize H3GeGeMe3, but we failed to isolate it.
Treatment of 1 with H3GeGeEt3 at a 3/2 molar ratio in toluene
afforded the bis(μ3-germylyne)triplatinum complex
[Pt3(dppe)3(μ3-GeH)(μ3-GeGeEt3)] (5) in 9.5% yield
(Scheme 3). The reaction was accompanied by the extrusion
Bond Angles (deg)
P(1)−Pt(1)−P(2)
Ge(1)−Pt(1)−Ge(3)
P(3)−Pt(2)−P(4)
Ge(1)−Pt(2)−Ge(3)
P(5)−Pt(3)−P(6)
Ge(1)−Pt(3)−Ge(3)
87.37(5)
Pt(1)−Ge(1)−Pt(2)
Pt(1)−Ge(1)−Pt(3)
Pt(2)−Ge(1)−Pt(3)
Pt(1)−Ge(3)−Pt(2)
Pt(1)−Ge(3)−Pt(3)
Pt(2)−Ge(3)−Pt(3)
88.751(18)
86.914(16)
90.484(18)
92.070(18)
89.985(17)
93.905(19)
69.984(17)
87.13(5)
Scheme 3. Formation Process of 5 in the Reaction of 1 with
H3GeGeEt3
70.007(18)
87.26(5)
69.966(17)
diphenylphosphino group and the triethylgermyl one. The
Pt···Pt interatomic distances of 3.42−3.54 Å were similar to
those of the bis(μ3-silylyne)triplatinum complex
[Pt3(dppe)3(μ3-SiR)2] (R = H, Me) with a Pt3Si2 core,13
despite the substitution of main-group elements. The other
M3Ge2 clusters had the following M−M single-bond lengths:
[Fe3(CO)9(μ3-GeEt)2], 2.73 Å;6c [Fe3(CO)9(μ3-Ge{Fe-
(CO)2(η5-C5H5)}2)], 2.72 Å;6c [Ru3(CO)9(μ3-Ge{Ru-
8
(CO)2(η5-C5Me4H)})2], 2.90 Å. For the H NMR spectrum
of 5 in C6D6, the Ge−H peak was observed as a broad signal at
3.0−3.4 ppm due to coupling with six 31P and three 195Pt
nuclei. The relatively simple spectral pattern was attributed to
the 3-fold rotation axis along the Ge−Ge alignment, which
agreed with the two near phosphorus resonances at 34.26 and
34.35 ppm in the 31P NMR spectrum of 5.
1
of Et3GeH, which was detected by 1H NMR spectroscopy. The
crystal structure of 5 (Figure 3, Table 1) showed that the
To investigate the formation process of 5, a 31P NMR
experiment was performed with a molar ratio of [1] to
[H3GeGeEt3] of 1/1, because the reaction rate is too fast to
detect the reaction intermediates under stoichiometric
conditions (Figure 4). The 31P NMR spectrum at room
Figure 3. Crystal structure of 5, showing 50% probability thermal
ellipsoids. The hydrogen atoms, except for that on Ge(3), are omitted
for clarity.
Figure 4. 31P NMR spectra for the reaction of 1 with H3GeGeEt3 at a
molar ratio of 1/1 in toluene-d8 at room temperature (A) and at 80 °C
for 24 h (B).
complex contained a trigonal-bipyramidal core consisting of
three platinum atoms on the equatorial plane and two
germanium atoms in the apical positions. One of the two μ3-
bridged germylynes maintained the Ge−Ge bond, which was
the same as in the cases of 3 and 4. The platinum centers had
four-coordinated distorted-square-planar geometry, and the
Pt−Ge bond length (ca. 2.49 Å) associated with μ3-Ge(GeEt3)
was longer than that of μ3-GeH (ca. 2.42 Å), which was
attributed to minimizing the steric repulsion between the
temperature showed two sets of two singlets (δ 56.6 (1JPtP
=
2040 Hz)/59.4 (1JPtP = 1752 Hz) and 55.3 (1JPtP = 1824 Hz)/
56.3 (1JPtP = 2086 Hz)), and two doublets of doublets (δ 55.0
2
4
(1JPtP = 1917 Hz, JPP = 8.1 Hz, JPP = 6.2 Hz)/55.8 (1JPtP
=
3
2
4
1920 Hz, JPtP = 103 Hz, JPP = 8.0 Hz, JPP = 6.2 Hz)) with
195Pt satellites assignable to the digermylplatinum hydride (I-
6638
dx.doi.org/10.1021/om3007147 | Organometallics 2012, 31, 6635−6641

Organometallics
Article
1′), the bis(germyl)platinum complex (I-2′), and the bis(μ-
germylene)diplatinum complex (I-3), respectively. The two
doublets of doublets of I-3 were similar to those of 3 and 4,
indicating that the two different germylene ligands were
bridged between two platinum centers. Incubation at 80 °C
for 24 h allowed the consumption of monomer intermediates
(I-1′, I-2′) and the simultaneous appearance of 5, with the
remaining diplatinum complex I-3. The spectral data suggested
that the sterically less hindered germylene ligands in I-3,
generated from I-1′ with I-2′, might induce the addition of I-2′
followed by the formal reductive elimination of GeH4 and
Et3GeH to afford 5. The reaction of I-3 with 1 is considered to
proceed more rapidly than that with I-2′, because the reaction
took place under conditions using 1.5 mol equiv of 1 relative to
H3GeGeEt3.
those of the silicon analogue [Pt4(dppe)4(μ4-Si)] and other
complexes including the spiro-M4Ge fragment.30 Although the
formation of the M4E (E = Si, Ge) fragment was achieved by
treatment of SiH4 and GeH4, our method mentioned so far
using the unsymmetrical digermane H3GeGeEt3 as well as
disilane H3SiSiMe2 Bu is a safe and convenient procedure to
regulate the molar ratio to metal sources.
t
CONCLUSION
■
We prepared the 1,1,1-triethyldigermane H3GeGeEt3 by a
formally direct hydrogenation from H2PhGeGeEt3 in the
presence of CF3CO2H and studied the reaction of the
zerovalent platinum complex [Pt(dppe)(η2-C2H4)] (1) with
unsymmetrical digermanes to afford polyhedral platinum−
germanium clusters. The sterically bulky substituents on the
digermanes involved multinucleation of product, that is, the
digermylplatinum hydride 2 from HPh2GeGeMe3 and the
bis(digermylene)diplatinum complexes 3 and 4 from
H2PhGeGeR3, and the desired bis(digermylyne)triplatinum
complex 5 provided a trigonal-bipyramidal skeleton from
H3GeGeEt3. In contrast with the silicon system, the Ge−Ge
bond was relatively inert during the formation process and
remained in one of the two bridging germylene or germylyne
ligands. These results are consistent with the fact that Ge−Ge
bond formation on the platinum center often occurs.
On the other hand, a change of the molar ratio of 1 to
H3GeGeEt3 to 4/1 resulted in the formation of the spiro-type
tetraplatinum complex [Pt4(dppe)4(μ4-Ge)] (6) in 36% yield
(Scheme 4). The 1H NMR spectrum during the formation of 6
Scheme 4. Formation of Spiro-Pt4Ge Cluster 6 for the
Reaction of 1 with H3GeGeEt3
EXPERIMENTAL SECTION
■
General Procedure. All experiments were carried out using
standard vacuum line and Schlenk techniques in an Ar atmosphere or
drybox. All the reagents were of the highest grade available and were
used without further purification. All solvents used for the syntheses
were distilled according to the general procedure. Benzene-d6 and
toluene-d8 were distilled from potassium metal under an Ar
atmosphere. HPh2GeGeMe3 and [Pt(dppe)(C2H4)] (1) were
synthesized according to the previously reported methods.31,32 The
NMR spectral measurements were performed on a JEOL AL-300
NMR spectrometer at 300 MHz for 1H and 122 MHz for 31P. The 1H
chemical shifts were corrected relative to the residual protonated
solvent according to the literature.33 The 31P chemical shift is
corrected relative to external H3PO4 (0 ppm). Elemental analysis was
performed on a Thermo Scientific FLASH 2000 corrected by
acetoanilide.
was so complex that the observed species could not be
assigned, which is not apparent for the formation process of 6.
X-ray diffraction analysis of 6 (Figure 5) showed that the
germanium atom had a tetragonal geometry with a Pt4 donor
set, of which the two diplatinum units {Pt2(dppe)} with a Pt−
Pt single bond were bridged by two dppe ligands. The Pt−Ge
bond lengths were 2.42−2.45 Å, diagnostic of a typical Pt−Ge
bond length, and the Pt−Ge−Pt bond angles were similar to
Synthesis of H2PhGeGeMe3. To PhGeH3 (0.820 g, 5.40 mmol)
t
in THF (10 mL) was added a pentane solution of BuLi (3.4 mL, 5.4
mmol) at −80 °C, and the solution was stirred and gradually warmed
to −60 °C. Me3GeCl (0.820 g, 5.40 mmol) was added to the resulting
solution and cooled to −80 °C. After continuous stirring at room
temperature, the organic layer was washed with water and dried by
anhydrous sodium sulfate. The reaction solution was filtered, and
volatiles were removed from the filtrate under reduced pressure
carefully. Purification by trap-to-trap distillation afforded
H2PhGeGeMe3 as a colorless oil. Yield: 0.43 g (30%). 1H NMR
(benzene-d6): δ 7.5−7.4 (m, 2H, Ph), 7.2−7.1 (m, 3H, Ph), 4.40 (s,
2H, GeH), 0.28 (s, 9H, CH3). 13C NMR (benzene-d6): δ 135.8 (Ph),
134.5 (Ph ipso), 128.6 (Ph), 128.5 (Ph), −0.9 (Me). EI-MS: m/z (%
relative intensity) 270 (M+, 10), 253 (M+ − H2 − Me, 9), 151 (M+ −
H2 − GeMe3, 42), 119 (M+ − GePhH2, 100).
Synthesis of H2PhGeGeEt3. H2PhGeGeEt3 was synthesized by
the same method as for H2PhGeGeMe3, except for use of Et3GeCl
instead of Me3GeCl and scaling up to 38.0 mmol for all reagents.
1
Figure 5. Crystal structure of 6, showing 50% probability thermal
ellipsoids. The hydrogen atoms are omitted for clarity. Selected bond
lengths (A) and angles (deg): Pt(1)−Pt(2) = 2.6395(4), Pt(3)−Pt(4)
= 2.6788(5), Pt(1)−Ge(1) = 2.4382(8), Pt(2)−Ge(1) = 2.4506(9),
Pt(3)−Ge(1) = 2.4436(9), Pt(4)−Ge(1) = 2.4236(9); Pt(1)−Ge(1)−
Pt(2) = 65.36(2), Pt(3)−Ge(1)−Pt(4) = 66.78(2).
Yield: 6.70 g (57%). H NMR (benzene-d6): δ 7.6−7.5 (m, 2H, Ph),
7.2−7.1 (m, 3H, Ph), 4.42 (s, 2H, GeH), 1.03 (t, 9H, J = 7.8 Hz,
CH2CH3), 0.87 (q, 6H, J = 8.1 Hz, CH2CH3). 13C NMR (benzene-
d6): δ 135.9 (Ph), 134.6 (Ph ipso), 128.5 (Ph), 128.4 (Ph), 10.1
(CH2CH3), 6.0 (CH2CH3). Anal. Calcd for H2PhGeGeEt3
(C12H22Ge2): C, 46.26; H, 7.12. Found: C, 46.49; H, 7.26. EI-MS:
6639
dx.doi.org/10.1021/om3007147 | Organometallics 2012, 31, 6635−6641

Organometallics
Article
m/z (% relative intensity) 312 (M+, 7), 283 (M+ − Et, 10), 255 (M+ +
H − Et2, 16), 225 (M+ − Et3, 22), 151 (M+ − H2 − GeMe3, 37), 161
(M+ − GePhH2, 100), 151 (M+ − H2 − GeEt3, 91).
CH2CH3), 0.33 (q, 6H, J = 7.6 Hz, CH2CH3). 31P{1H} NMR
(benzene-d6): δ 34.35 (s, 1JPtP = 2197 Hz, 3JPtP = 83 Hz), 34.26 (s, 1JPtP
3
= 2572 Hz, JPtP = 83 Hz). IR (KBr, cm−1): ν(Ge−H) 1959 m. Anal.
Calcd for 5·C6H6 (C90H94Ge3P6Pt3): C, 49.94; H, 4.38. Found: C,
50.21; H, 4.01.
Synthesis of H3GeGeEt3. CF3COOH (1.80 g, 16.0 mmol) was
added to a CH2Cl2 solution (45 mL) of H2PhGeGeEt3 (5.00 g, 16.0
mmol) at −50 °C, and the solution was stirred overnight at 0 °C. After
removal of all volatiles under reduced pressure, CH2Cl2 (45 mL) and
CF3COOH (1.80 g, 16.0 mmol) were added to the residue at −50 °C.
The solution was stirred for 3 days at room temperature and then was
evaporated under reduced pressure. The residue was dissolved in Et2O
(40 mL), the ether solution was added dropwise to a suspension of
LiAlH4 (0.61 g, 16.0 mmol) in Et2O (30 mL) on ice bath, and the
suspension was stirred for 24 h.16 The reaction mixture was quenched
by the addition of H2O and filtered, and the solvent was removed from
the filtrate by careful distillation. Purification by trap-to-trap distillation
[Pt4(dppe)4(μ4-Ge)] (6). To a toluene solution (2 mL) of 1 (20 mg,
32 μmol) was added a toluene solution (1 mL) of H3GeGeEt3 (1.9
mg, 8.1 μmol) at −30 °C, and the resulting solution was allowed to
stand for 3 weeks at room temperature. Hexane (2 mL) was added,
and the solution was allowed to stand for 1 week to afford dark brown
crystals. Yield: 7.0 mg (36%). 1H NMR (benzene-d6): δ 7.74 (br s, 4H,
Ph), 7.5−7.3 (br, 4H, Ph), 7.27 (br s, 4H, Ph), 7.1−6.7 (m, 20H, Ph),
6.73 (t, 4H, J = 7.5 Hz, Ph), 6.65 (t, 4H, J = 7.5 Hz, Ph), 4.2−3.9 (br,
4H, CH2P), 3.1−2.8 (br, 4H, CH2P), 2.47 (br s, 8H, CH2P). Anal.
Calcd for 6·2.5(toluene) (C121.5H116GeP8Pt4): C, 54.51; H, 4.37.
Found: C, 54.41; H, 4.08.
1
afforded H3GeGeEt3 as a colorless oil. Yield: 0.69 g (18%). H NMR
X-ray Crystallography. Single crystals suitable for XRD analyses
were obtained from toluene/hexane solutions for 2−4 and benzene/
hexane solutions for 5 and 6. Each crystal was mounted on a glass
fiber, and the diffraction data were collected on a Bruker APEX II
CCD detector using graphite-monochromated Mo Kα radiation at 123
K (Table S1).
All the structures were solved by a combination of direct methods
and Fourier techniques, and all the non-hydrogen atoms were
anisotropically refined by full-matrix least-squares calculations. The
atomic scattering factors and anomalous dispersion terms were
obtained from ref 35. The refinement of all structures was carried
out by full-matrix least-squares methods of SHELXL-97.36
(benzene-d6): δ 3.15 (s, 3H, GeH3), 1.01 (t, 9H, CH2CH3), 0.79 (q,
6H, J = 8.8 Hz, CH2CH3). 13C NMR (benzene-d6): δ 7.0 (CH2CH3),
6.1 (CH2CH3). EI-MS: m/z (% relative intensity) 236 (M+, 7), 207
(M+ − Et, 20), 179 (M+ + H − Et2, 37), 161 (M+ − GePhH2, 100).
Preparation of Platinum Complexes. [Pt(dppe)(H)-
(GePh2GeMe3)] (2). To HPh2GeGeMe3 (28 mg, 80.4 μmol) in
toluene (1 mL) was added a toluene solution (1 mL) of 1 (50.0 mg,
80.4 μmol) at room temperature, and hexane (2 mL) was added to the
resulting solution. The solution was allowed to stand for 2 days to
afford colorless crystals. Yield: 29.6 mg (39%). 1H NMR (benzene-d6):
δ 7.82 (d, 8H, J = 6.9 Hz, Ph), 7.27 (t, 4H, J = 8.4 Hz, Ph), 7.1−6.8
(m, 18H, Ph), 2.0−1.6 (m, 4H, PCH2), 0.59 (s, 9H, GeMe3), −0.21
1
2
2
(dd, 1H, JPtH = 1019 Hz, JPH = 175 Hz (trans), JPH = 11 Hz (cis),
1
PtH). 31P{1H} NMR (benzene-d6): δ 59.3 (s, JPtP = 1996 Hz), 55.4
ASSOCIATED CONTENT
1
■
(s, JPtP
= 2033 Hz). Anal. Calcd for 2·0.2(toluene)
(C42.4H45.6Ge2P2Pt): C, 53.18; H, 4.80. Found: C, 53.11; H, 4.76.34
[Pt2(dppe)2(μ-GeHPh)(μ-Ge(Ph)GeMe3)] (3). To H2PhGeGeMe3
(22 mg, 82 μmol) in toluene (1 mL) was added a toluene solution
(2 mL) of 1 (50.0 mg, 80.4 μmol) at −30 °C, and the resulting
solution was allowed to stand for 24 h. Hexane (1 mL) was added to
the resulting solution. The solution was allowed to stand for 2 days to
afford yellow crystals. Yield: 27.8 mg (42%). 1H NMR (benzene-d6): δ
7.99 (t, 4H, J = 8.4 Hz, Ph), 7.75 (t, 4H, J = 7.2 Hz, Ph), 7.6−7.4 (m,
4H, Ph), 7.2−6.6 (m, 48H, Ph), 4.0−3.7 (m, 1H, GeH), 2.1−1.2 (m,
8H, CH2P), 0.47 (s, 9H, GeMe3). 31P{1H} NMR (benzene-d6): δ 58.0
(d, 1JPtP = 1831 Hz, 3JPtP = 175 Hz, 2JPP2 = 20 Hz, 4JPP = 9.4 Hz), 56.7
* Supporting Information
S
A figure giving selected 31P NMR spectra for the reaction of 1
with H2PhGeGeEt3 and a table and CIF files giving
crystallographic data for the platinum−germanium complexes
2−6. This material is available free of charge via the Internet at
http://pubs.acs.org.
AUTHOR INFORMATION
■
Corresponding Author
1
3
4
*Tel: +81-3-3986-0221. Fax: +81-3-5992-1029. E-mail: kunio.
mochida@gakushuin.ac.jp.
(d, JPtP = 1863 Hz, JPtP = 265 Hz, JPP = 20 Hz, JPP = 9.4 Hz)
1
3
([Pt(dppe)(μ-GeHPh)]2: 57.1 (s, JPtP = 1792 Hz, JPtP = 336 Hz)).
IR (KBr, cm−1): ν(Ge−H) 1982 m, 1905 m. Anal. Calcd for
(3)0.9·([Pt(dppe)(μ-GeHPh)]2)0.1 (C66.7H67.2Ge2.9P4Pt2): C, 50.27; H,
4.25. Found: C, 49.83; H, 4.00.
Notes
The authors declare no competing financial interest.
[Pt2(dppe)2(μ-GeHPh)(μ-Ge(Ph)GeEt3)] (4). To H2PhGeGeEt3
(12.6 mg, 53.6 μmol) in toluene (1 mL) was added a toluene
solution (1 mL) of 1 (50.0 mg, 80.4 μmol) at room temperature, and
the resulting solution was stirred at 80 °C for 24 h. Hexane (1 mL)
was added to the resulting solution. The solution was allowed to stand
ACKNOWLEDGMENTS
■
This work was financially supported by a Grant-in-Aid for
Scientific Research on Priority Areas (No. 21550066) from the
Ministry of Education, Culture, Sports, Science and Technol-
ogy of Japan.
1
for 2 days to afford yellow crystals. Yield: 19.4 mg (29%). H NMR
(benzene-d6): δ 7.98 (t, 4H, J = 8.4 Hz, Ph), 7.85 (t, 4H, J = 8.1 Hz,
Ph), 7.6−7.4 (m, 2H, Ph), 7.3−6.7 (m, 50H, Ph), 3.8−3.5 (m, 1H,
GeH), 2.2−1.5 (m, 8H, CH2P), 1.19 (t, 9H, J = 7.7 Hz, CH2CH3),
0.89 (q, 6H, J = 7.7 Hz, CH2CH3). 31P{1H} NMR (benzene-d6): δ
57.6 (d, 1JPtP = 1810 Hz, 3JPtP = 185 Hz, 2JPP = 23 Hz, 4JPP = 9.4 Hz),
55.2 (d, 1JPtP = 1888 Hz, 3JPtP = 283 Hz, 2JPP = 23 Hz, 4JPP = 9.4 Hz).
IR (KBr, cm−1): ν(Ge−H) 1874 m. Anal. Calcd for 4
(C70H74Ge3P4Pt2): C, 51.04; H, 4.53. Found: C, 51.25; H, 4.49.
[Pt3(dppe)3(μ3-GeH)(μ3-GeGeEt3)] (5). To H3GeGeEt3 (12.6 mg,
53.5 μmol) in benzene (2 mL) was added a benzene solution (2 mL)
of 1 (50.0 mg, 80.4 μmol) at room temperature, and the resulting
solution was stirred at 80 °C for 2 days. Hexane (6 mL) was added to
the resulting solution. The solution was allowed to stand for 2 days to
afford orange crystals. Yield: 5.3 mg (9.5%). 1H NMR (benzene-d6): δ
8.3−8.2 (m, 12H, Ph), 7.30 (t, 18H, J = 7.2 Hz, Ph), 7.2−7.1 (m, 12H,
Ph), 6.98 (t, 6H, J = 6.9 Hz, Ph), 6.84 (t, 12H, J = 6.9 Hz, Ph), 3.4−3.0
(br, 1H, GeH), 2.1−1.7 (m, 12H, CH2P), 0.59 (t, 9H, J = 7.8 Hz,
REFERENCES
■
(1) Hogarth, G.; Kabir, S. E.; Nordlander, E. Dalton Trans. 2010, 39,
6153−6174.
(2) Santos, P. C. D.; Dean, D. R.; Hu, Y.; Ribbe, M. W. Chem. Rev.
2004, 104, 1159−1173.
(3) Adams, R. D. Chem. Rev. 1989, 89, 1703−1712.
(4) (a) Hungria, A. B.; Raja, R.; Adams, R. D.; Captain, B.; Thomas,
J. M.; Midgley, P. A.; Golovko, V.; Johnson, B. F. G. Angew. Chem., Int.
Ed. 2006, 45, 4782−4785. (b) Adams, R. D.; Blom, D. A.; Captain, B.;
Raja, R.; Thomas, J. M.; Trufan, E. Langmuir 2008, 24, 9223−9226.
(c) He, W.; Wang, L.; Sun, C.; Wu, K.; He, S.; Chen, J.; Wu, P.; Yu, Z.
Chem. Eur. J. 2011, 17, 13308−13317. (d) Dias, R. P.; Rocha, W. R.
Organometallics 2011, 30, 4257−4268. (e) Adams, R. D.; Trufan, E.
Philos. Trans. R. Soc. A 2010, 268, 1473−1493.
6640
dx.doi.org/10.1021/om3007147 | Organometallics 2012, 31, 6635−6641

Organometallics
Article
(5) Adams, R. D.; Boswell, E. M.; Captain, B.; Hungria, A. B.;
Midgley, P. A.; Raja, R.; Thomas, J. M. Angew. Chem., Int. Ed. 2007, 46,
8182−8185.
(6) (a) Foster, S. P.; Mackay, K. M.; Nicholson, B. K. Inorg. Chem.
1985, 24, 909−913. (b) Anema, S. G.; Mackay, K. M.; McLeod, L. C.;
Nicholson, B. K.; Whittaker, J. M. Angew. Chem., Int. Ed. Engl. 1986,
25, 759−760. (c) Anema, S. G.; Mackay, K. M.; Nicholson, B. K.; Tiel,
M. V. Organometallics 1990, 9, 2436−2442.
ppm (sept, J = 3.0 Hz) for Et3GeH was observed with a H2 signal at
4.51 ppm, although the ethyl groups of Et3GeH overlapped those of 4.
(23) Klinkhammer, K. W. The Chemistry of Organic Germanium, Tin
and Lead Compounds; Rappoport, Z., Ed.; Wiley: West Sussex, U.K.,
2002; Vol. 2, pp 283−357.
(24) Sakaki, S.; Yamaguchi, S.; Musashi, Y.; Sugimoto, M. J.
Organomet. Chem. 2001, 635, 173−186.
(25) (a) Zarate, E.; Tessier-Youngs, C. A.; Youngs, W. J. J. Am. Chem.
Soc. 1988, 110, 4068−4070. (b) Sanow, L. M.; Chai, M.; McConnville,
D. B.; Galat, K. J.; Simons, R. S.; Rinaldi, P. L.; Youngs, W. J.; Tessier,
C. A. Organometallics 2000, 19, 192−205. (c) Braddock-Wilking, J.;
Levchinsky, Y.; Rath, N. P. Organometallics 2001, 20, 474−480.
(26) (a) Braddock-Wilking, J.; Levchinsky, Y.; Rath, N. P. Inorg.
Chim. Acta 2002, 330, 82−88. (b) Tanabe, M.; Ito, D.; Osakada, K.
Organometallics 2008, 27, 2258−2267.
(27) (a) Braddock-Wilking, J.; Bandrowsky, T.; Praingam, N.; Rath,
N. P. Organometallics 2009, 28, 4098−4105. (b) Tanabe, M.;
Hanzawa, M.; Ishikawa, N.; Osakada, K. Organometallics 2009, 28,
6014−6019. (c) Tanabe, M.; Deguchi, T.; Osakada, K. Organometallics
2011, 30, 3386−3391.
(7) (a) Adams, R. D.; Captain, B.; Smith, J. L., Jr. Inorg. Chem. 2005,
44, 1413−1420. (b) Adams, R. D.; Smith, J. L., Jr. Inorg. Chem. 2005,
44, 4276−4281. (c) Adams, R. D.; Boswell, E. M.; Captain, B.; Patel,
M. A. Inorg. Chem. 2007, 46, 533−540. (d) Adams, R. D.; Trufan, E.
Inorg. Chem. 2010, 49, 3029−3034. (e) Adams, R. D.; Trufan, E.
Organometallics 2010, 29, 4346−4353. (f) Adams, R. D.; Kan, Y.;
Zhang, Q. Organometallics 2011, 30, 328−333. (g) Adams, R. D.;
Fang, F.; Zhang, Q.; Hall, M. B.; Trufan, E. Organometallics 2012, 31,
2621−2630.
(8) Zhang, Y.; Wang, B.; Xu, S.; Zhou, X. Organometallics 2001, 20,
3829−3832.
(9) Tanabe, M.; Ishikawa, N.; Chiba, M.; Ide, T.; Osakada, K.;
Tanase, T. J. Am. Chem. Soc. 2011, 133, 18598−18601.
(10) Nickel complexes: (a) Yang, J.; Rosal, I. D.; Fasulo, M.;
Sangtrirutnugul, P.; Maron, L.; Tilley, T. D. Organometallics 2010, 29,
5544−5550. (b) Beck, R.; Johnson, S. A. Organometallics 2012, 31,
3599−3609.
(28) By monitoring the reaction of 1 with H2PhGeGeEt3 in toluene-
d8 with NMR spectroscopy, it was clarified that I-1 was rapidly formed
at −30 °C. Warming the solution to 80 °C afforded a mixture of I-1, I-
2, and the diplatinum complex 4, indicating the slow conversion of I-1
into I-2. See the Supporting Information.
(29) The ratio of 3 to [Pt(dppe)(μ-GeHPh)]2 was estimated to be
(11) Palladium complexes: (a) Chen, W.; Shimada, S.; Tanaka, M.
Science 2002, 295, 308−310. (b) Shimada, S.; Li, Y.-H.; Choe, Y.-K.;
Tanaka, M.; Bao, M.; Uchimaru, T. Proc. Natl. Acad. Sci. 2007, 104,
7758−7763. (c) Armbruster, F.; Meyer, J.; Baldes, A.; Burgos, P. O.;
1
ca. 9/1 by the H NMR spectrum and elemental analysis.
(30) (a) Gerlach, R. F.; Mackay, K. M.; Nicholson, B. K. J. Chem. Soc.,
Dalton Trans. 1981, 80−84. (b) Anema, S. G.; Mackay, K. M.;
Nicholson, B. K. J. Chem. Soc., Dalton Trans. 1996, 3853−3858.
́
Fernandez, I.; Breher, F. Chem. Commun. 2011, 47, 221−223.
(31) Castel, A.; Riviere, P.; Stage,
9, 205−210.
́
J.; Ko, H. Y. Organometallics 1990,
(12) Platinum complexes: (a) Osakada, K.; Tanabe, M.; Tanase, T.
Angew. Chem., Int. Ed. 2000, 39, 4053−4055. (b) Braddock-Wilking, J.;
Corey, J. Y.; Dill, K.; Rath, N. P. Organometallics 2002, 21, 5467−5469.
(c) Braddock-Wilking, J.; Corey, J. Y.; French, L. M.; Choi, E.;
Speedie, V. J.; Rutherford, M. F.; Yao, S.; Xu, H.; Rath, N. P.
Organometallics 2006, 25, 3974−3988. (d) Yamada, T.; Mawatari, A.;
Tanabe, M.; Osakada, K.; Tanase, T. Angew. Chem., Int. Ed. 2009, 48,
568−571.
(32) Head, R. H. J. Chem. Soc., Dalton Trans. 1982, 1637−1639.
(33) Fulmer, G. R.; Miller, A. J. M.; Sherden, N. H.; Gottlieb, H. E.;
Nudelman, A.; Stoltz, B. M.; Bercaw, J. E.; Goldberg, K. I.
Organometallics 2010, 29, 2176−2179.
(34) The solvent used in recrystallization could not be removed
completely.
(35) Ibers, J. A., Hamilton, W. C. International Tables for X-ray
Crystallography; Kynoch Press: Birmingham, U.K., 1974; Vol. IV.
(36) Sheldrick, G. M. Acta Crystallogr., Sect. A 2008, 64, 112−122.
(13) (a) Arii, H.; Takahashi, M.; Nanjo, M.; Mochida, K.
Organometallics 2009, 28, 4629−4631. (b) Arii, H.; Takahashi, M.;
Nanjo, M.; Mochida, K. Organometallics 2011, 30, 917−920.
(14) Amadoruge, M. L.; Weinert, C. S. Chem. Rev. 2008, 108, 4253−
4294.
(15) Simon, D.; Haberle, K.; Drager, M. J. Organomet. Chem. 1984,
̈
̈
267, 133−142.
(16) LiAlH4 hydrogenated the unidentified materials to remove them
as volatiles, which is convenient to isolate H3GeGeEt3 by trap-to-trap
distillation.
(17) (a) Habereder, T.; Noth, H. Appl. Organomet. Chem. 2003, 17,
̈
525−538. (b) White, C. P.; Braddock-Wilking, J.; Corey, J. Y.; Xu, H.;
Redekop, E.; Sedinkin, S.; Rath, N. P. Organometallics 2007, 26, 1996−
2004. (c) Arii, H.; Nanjo, M.; Mochida, K. Organometallics 2008, 27,
4147−151. (d) Nakata, N.; Fukazawa, S.; Ishii, A. Organometallics
2009, 28, 534−538.
(18) Arii, H.; Takahashi, M.; Nanjo, M.; Mochida, K. Dalton Trans.
2010, 39, 6434−6440.
(19) (a) Koizumi, T.; Osakada, K.; Yamamoto, T. Organometallics
1997, 16, 6014−6016. (b) Braddock-Wilking, J.; Corey, J. Y.; Trankler,
K. A.; Dill, K. M.; French, L. M.; Rath, N. P. Organometallics 2004, 23,
4576−4584. (c) Voigt, J.; Braun, T. Dalton Trans. 2011, 40, 12699−
12704.
(20) Zhu, J.; Lin, Z.; Marder, T. B. Inorg. Chem. 2005, 44, 9384−
9390.
(21) Braddock-Wilking, J.; Corey, J. Y.; White, C.; Xu, H.; Rath, N. P.
Organometallics 2005, 24, 4113−4115.
(22) The 1H signals of H2 and Me3GeH during the reaction of 1 with
H2PhGeGeMe3 in toluene-d8 were observed at 4.51 and 4.02 ppm
(dec, J = 3.3 Hz, Ge−H)/0.16 ppm (d, J = 3.3 Hz, GeMe),
respectively. In the case of H2PhGeGeEt3, the Ge−H signal at 3.88
6641
dx.doi.org/10.1021/om3007147 | Organometallics 2012, 31, 6635−6641