Preparation of oligogermanes via the hydrogermolysis reaction

Article abstract of DOI:10.1021/om060115x

The hydrogermolysis reaction has been shown to be useful for the formation of germanium-germanium bonds. The Ge - Ge bond forming reaction involves a germanium amide and a germanium hydride and requires the use of acetonitrile as the solvent. A key factor in the formation of the Ge - Ge bond involves reaction of the germanium amide R₃GeNMe₂ with acetonitrile solvent to furnish an α-germylated nitrile R₃GeCH₂CN which contains a labile Ge - C bond. This species undergoes subsequent reaction with a germanium hydride R₃GeH to form the Ge - Ge bond. Using this method, the digermanes Buⁿ₃GeGePh₃ and Et ₃GeGePh₃ have been obtained and their X-ray crystal structures have been determined. The preparation of three synthons for stepwise oligogermane chain buildup, R₂Ge(NMe₂)CH ₂CH₂OEt (R = Et, Bu, Ph), has also been achieved. These synthons react with Ph₃GeH in CH₃CN to afford the corresponding digermanes, which in the case of R = Et and Bu undergo subsequent reaction with DIBAL-H to generate a digermane hydride. The ethyl and n-butyl digermane hydrides then are subsequently reacted with an additional equivalent of the appropriate synthon to produce the corresponding trigermanes, and repetition of these two steps furnishes the tetragermanes Ph ₃GeGe(R₂)Ge(R₂)Ge(R₂)CH ₂CH₂OEt (R = Et, Bu). Thus, in this study two new series of oligomeric organogermanium species have been prepared and fully characterized.

Full text of DOI:10.1021/om060115x

Organometallics 2006, 25, 3211-3219
3211
Preparation of Oligogermanes via the Hydrogermolysis Reaction
Esla Subashi,† Arnold L. Rheingold,‡ and Charles S. Weinert*,†
Department of Chemistry, Oklahoma State UniVersity, Stillwater, Oklahoma, 74078, and Department of
Chemistry and Biochemistry, UniVersity of California-San Diego, La Jolla, California 92093-0303
ReceiVed February 3, 2006
The hydrogermolysis reaction has been shown to be useful for the formation of germanium-germanium
bonds. The Ge-Ge bond forming reaction involves a germanium amide and a germanium hydride and
requires the use of acetonitrile as the solvent. A key factor in the formation of the Ge-Ge bond involves
reaction of the germanium amide R3GeNMe2 with acetonitrile solvent to furnish an R-germylated nitrile
R3GeCH2CN which contains a labile Ge-C bond. This species undergoes subsequent reaction with a
germanium hydride R3GeH to form the Ge-Ge bond. Using this method, the digermanes Bun GeGePh3
3
and Et3GeGePh3 have been obtained and their X-ray crystal structures have been determined. The
preparation of three synthons for stepwise oligogermane chain buildup, R2Ge(NMe2)CH2CH2OEt (R )
Et, Bu, Ph), has also been achieved. These synthons react with Ph3GeH in CH3CN to afford the
corresponding digermanes, which in the case of R ) Et and Bu undergo subsequent reaction with DIBAL-H
to generate a digermane hydride. The ethyl and n-butyl digermane hydrides then are subsequently reacted
with an additional equivalent of the appropriate synthon to produce the corresponding trigermanes, and
repetition of these two steps furnishes the tetragermanes Ph3GeGe(R2)Ge(R2)Ge(R2)CH2CH2OEt (R )
Et, Bu). Thus, in this study two new series of oligomeric organogermanium species have been prepared
and fully characterized.
systems remain less developed. However, a variety of oligomeric
organogermanes have been prepared,4,6,7,39-62 and many of these
species exhibit properties that are dependent on the number of
catenated germanium atoms and/or the identity of the organic
side groups.4,6,7,11,12,63 For example, it has been shown that a
series of linear permethylated oligogermanes exhibits a decreas-
ing ionization potential as the length of the Ge-Ge chain is
Introduction
There is current interest in the preparation of catenated
compounds of the heavier group 14 elements due to their
inherent σ-delocalization1-3 which often results in interesting
and useful optical and electronic properties in these systems.1-12
The preparation of both oligomeric and polymeric linear species
has been investigated and the properties of these systems are
tunable, as they rely on the number of catenated atoms in the
chain as well as on the substituents attached to the element-
element backbone.
(15) Shankar, R.; Saxena, A.; Brar, A. S. J. Organomet. Chem. 2002,
650, 223-230.
(16) Kashimura, S.; Ishifune, M.; Yamashita, N.; Bu, H.-B.; Takebayashi,
M.; Kitajima, S.; Yoshiwara, D.; Kataoka, Y.; Nishida, R.; Kawasaki, S.;
Murase, H.; Shono, T. J. Org. Chem. 1999, 64, 6615-6621.
(17) Kimata, Y.; Suzuki, H.; Satoh, S.; Kuriyama, A. Organometallics
1995, 14, 2506-2511.
(18) Lacave-Goffin, B.; Hevesi, L.; Devaux, J. J. Chem. Soc., Chem.
Commun. 1995, 769-770.
(19) Miller, R. D.; Jenkner, P. K. Macromolecules 1994, 27, 5921-
5923.
The synthesis and properties of oligomeric and polymeric
silicon-13-23 and tin-containing24-38 systems have been exten-
sively investigated while those of the related germanium
* To whom correspondence should be addressed. E-mail: weinert@
chem.okstate.edu.
† Oklahoma State University.
(20) Hengge, E. F. J. Inorg. Organomet. Polym. 1993, 3, 287-303.
(21) Kimata, Y.; Suzuki, H.; Satoh, S.; Kuriyama, A. Chem. Lett. 1994,
1163-1164.
‡ University of California-San Diego.
(1) Miller, R. D.; Michl, J. Chem. ReV. 1989, 89, 1359-1410.
(2) Balaji, V.; Michl, J. Polyhedron 1991, 10, 1265-1284.
(3) Ortiz, J. V. Polyhedron 1991, 10, 1285-1297.
(22) Jones, R. G.; Benfield, R. E.; Cragg, R. H.; Swain, A. C.; Webb, S.
J. Macromolecules 1993, 26, 4878-4887.
(4) Bulten, E. J.; Noltes, J. G. J. Organomet. Chem. 1969, 16, P8-P10.
(5) Dra¨ger, M.; Ross, L.; Simon, D. ReV. Silicon, Germanium, Tin, Lead
Cmpds. 1983, 7, 299-445.
(23) Benfield, R. E.; Cragg, R. H.; Jones, R. G.; Swain, A. C. J. Chem.
Soc., Chem. Commun. 1992, 1022-1024.
(24) Choffat, F.; Smith, P.; Caseri, W. J. Mater. Chem. 2005, 15, 1789-
1792.
(6) Mochida, K.; Chiba, H. J. Organomet. Chem. 1994, 473, 45-54.
(7) Mochida, K.; Hata, R.; Shimoda, M.; Matsumoto, F.; Kurosu, H.;
Kojima, A.; Yoshikawa, M.; Masuda, S.; Harada, Y. Polyhedron 1996, 15,
3027-3032.
(25) Thompson, S. M.; Schubert, U. Inorg. Chim. Acta 2004, 357, 1959-
1964.
(26) Deacon, P. R.; Devylder, N.; Hill, M. S.; Mahon, M. F.; Molloy,
K. C.; Price, G. J. J. Organomet. Chem. 2003, 687, 46-56.
(27) Lu, V. Y.; Tilley, T. D. Macromolecules 2000, 33, 2403-2412.
(28) Okano, M.; Matsumoto, N.; Arakawa, M.; Tsuruta, T.; Hamano,
H. Chem. Commun. 1998, 1799-1800.
(29) Mochida, K.; Hayakawa, M.; Tsuchikawa, T.; Yokoyama, Y.;
Wakasa, M.; Hayashi, H. Chem. Lett. 1998, 91-92.
(30) Babcock, J. R.; Sita, L. R. J. Am. Chem. Soc. 1996, 118, 12481-
12482.
(31) Holder, S. J.; Jones, R. G.; Benfield, R. E.; Went, M. J. Polymer
1996, 37, 3477-3479.
(32) Lu, V.; Tilley, T. D. Macromolecules 1996, 29, 5763-5764.
(33) Imori, T.; Lu, V.; Cai, H.; Tilley, T. D. J. Am. Chem. Soc. 1995,
117, 9931-9940.
(8) Sita, L. R. Organometallics 1992, 11, 1442-1444.
(9) Sita, L. R. Acc. Chem. Res. 1994, 27, 191-197.
(10) Sita, L. R. AdV. Organomet. Chem. 1995, 38, 189-243.
(11) Rivie`re, P.; Rivie`re-Baudet, M.; Satge´, J. In ComprehensiVe
Organometallic Chemistry II; Abel, E. W., Stone, F. G. A., Wilkinson, G.,
Eds.; Pergamon: New York, 1995; Vol. 2, pp 137-216.
(12) Rivie`re, P.; Rivie`re-Baudet, M.; Satge´, J. In ComprehensiVe
Organometallic Chemistry; Wilkinson, G., Stone, F. G. A., Abel, E. W.,
Eds.; Pergamon: New York, 1982; Vol. 2, pp 399-518.
(13) Zuev, V. V.; Skvortsov, N. K. J. Polym. Sci. A: Polym. Chem.
2003, 41, 3761-3767.
(14) Bratton, D.; Holder, S. J.; Jones, R. G.; Wong, W. K. C. J.
Organomet. Chem. 2003, 685, 60-64.
10.1021/om060115x CCC: $33.50 © 2006 American Chemical Society
Publication on Web 05/13/2006

3212 Organometallics, Vol. 25, No. 13, 2006
Subashi et al.
increased.7 In a related series of perethylated oligogermanes,
the position of the absorbance maximum (λmax) undergoes a
red shift with increasing chain length,4 and the λmax in a group
of organopolygermanes also undergoes a bathochromic shift as
the steric bulk of the organic side groups is increased.6
Scheme 1
Traditional methods for the formation of germanium-
germanium bonds include germylene insertion into a Ge-X
bond (X ) N, O, or a halogen), Wurtz-type coupling reactions
involving organogermanium halides, reaction of organogerma-
nium anions with organogermanium halides, reaction of orga-
nolithium or Grignard reagents with germanium halides, thermal
decomposition of germylmercury compounds, and bond forma-
tion via hydrogermolysis reactions.5,11,12,63-65 An extensive series
of synthetic, spectroscopic, and structural investigations employ-
ing oligogermanes prepared by these methods was reported by
Dra¨ger et al.,39-56 but most of these studies were complicated
by low yields and/or the formation of mixtures of products. For
example, the preparation of Ge3Ph8 and Ge4Ph10 from GeCl4
and PhMgBr resulted in a mixture of these two products which
were also contaminated with Ge2Ph6 and GePh4. This mixture
required separation by HPLC giving the desired trigermane in
11% yield and the tetragermane in 18% yield.48 The preparation
of Ph3GeGe(Me)2GePh3 resulted in similar complications.45
Significant improvements in both product yield and selectivity
have been recently achieved by the reaction of triorganoger-
manium halides with an excess (10 equiv) of SmI2.57,58
The hydrostannolysis reaction has proven very useful for the
preparation of oligostannanes8-10,38,66 but the analogous reaction
is more difficult to perform in the case of germanium, typically
requiring the presence of electron-withdrawing substituents on
germanium to make the Ge-H bond more reactive. We are
interested in obtaining a library of fully characterized oligomeric
germanium systems to investigate the relationship between their
structures and their properties. Additionally, such a catalog of
compounds would be useful as small-molecule models for both
polymeric systems and functionalized germanium surfaces
bearing organic substituents. We have employed the hydrog-
ermolysis reaction for the stepwise preparation of discrete linear
oligogermanes in good to excellent yields as single molecules
rather than mixtures of products, and these results are the focus
of this paper.
(34) Sita, L. R.; Terry, K. W.; Shibata, K. J. Am. Chem. Soc. 1995, 117,
8049-8050.
Results and Discussion
(35) Imori, T.; Tilley, T. D. J. Chem. Soc., Chem. Commun. 1993, 1607-
1609.
To investigate the utility of the hydrogermolysis reaction for
(36) Adams, S.; Dra¨ger, M.; Mathiasch, B. J. Organomet. Chem. 1987,
326, 173-186.
the formation of Ge-Ge bonds, we prepared the digermanes 1,
(37) Adams, S.; Dra¨ger, M. J. Organomet. Chem. 1985, 288, 295-304.
(38) Sommer, R.; Schneider, B.; Neumann, W. P. Liebigs Ann. Chem.
1966, 692, 12-21.
2, and 3 starting with the germanium amides Bun GeNMe2 or
3
Et3GeNMe2 as shown in Scheme 1. Initially, the synthesis of 1
was attempted at room temperature using benzene as the solvent,
but no product was detected even using reaction times of up to
one week. Similarly, attempts to prepare 1 in refluxing benzene
or toluene were unsuccessful. However, when refluxing aceto-
nitrile was employed as the solvent, 1 was obtained in 83%
yield after 48 h.
(39) Dra¨ger, M.; Ross, L. Z. Anorg. Allg. Chem. 1980, 460, 207-216.
(40) Dra¨ger, M.; Ross, L.; Simon, D. Z. Anorg. Allg. Chem. 1980, 466,
145-156.
(41) Dra¨ger, M.; Ross, L. Z. Anorg. Allg. Chem. 1980, 469, 115-122.
(42) Dra¨ger, M.; Simon, D. Z. Anorg. Allg. Chem. 1981, 472, 120-128.
(43) Dra¨ger, M.; Ross, L. Z. Anorg. Allg. Chem. 1981, 476, 94-104.
(44) Dra¨ger, M.; Ha¨berle, K. J. Organomet. Chem. 1985, 280, 183-
196.
The formation of 1-3 can be most easily achieved by sealing
an acetonitrile solution of the reactants in a Schlenk tube and
heating at 80-90 °C for 48 h, and this technique was used for
the preparation of 1, 2, and 3, obtained in isolated yields of
87%, 84%, and 86%, respectively (Scheme 1). These yields are
generally higher than those usually obtained via other synthetic
methods. For example, But3GeGeBut3 was isolated in 16% yield
via the reduction of But3GeCl with lithium naphthalenide,62 Ph3-
GeGePh3 was obtained in 69% yield from the reaction of
(45) Dra¨ger, M.; Simon, D. J. Organomet Chem. 1986, 306, 183-192.
(46) Ha¨berle, K.; Dra¨ger, M. Z. Naturforsch. 1987, 42B, 323-329.
(47) Ha¨berle, K.; Dra¨ger, M. J. Organomet. Chem. 1986, 312, 155-
165.
(48) Roller, S.; Simon, D.; Dra¨ger, M. J. Organomet. Chem. 1986, 301,
27-40.
(49) Roller, S.; Dra¨ger, M. J. Organomet. Chem. 1986, 316, 57-65.
(50) Ross, L.; Dra¨ger, M. J. Organomet. Chem. 1980, 194, 23-32.
(51) Ross, L.; Dra¨ger, M. J. Organomet. Chem. 1980, 199, 195-204.
(52) Ross, L.; Dra¨ger, M. Z. Anorg. Allg. Chem. 1981, 472, 109-119.
(53) Ross, L.; Dra¨ger, M. Z. Naturforsch. 1983, 38B, 665-673.
(54) Ross, L.; Dra¨ger, M. Z. Anorg. Allg. Chem. 1984, 515, 141-146.
(55) Ross, L.; Dra¨ger, M. Z. Anorg. Allg. Chem. 1984, 519, 225-232.
(56) Simon, D.; Ha¨berle, K.; Dra¨ger, M. J. Organomet. Chem. 1984,
267, 133-142.
PhMgBr with GeCl4,59,60 and the coupling reaction of Bun GeK
3
and Me3GeCl furnished Bun GeGeMe3 in approximately 60%
3
yield.67 Digermanes can be obtained from the corresponding
trialkylgermanium hydrides when SmI2 is used as the reductant
in 39-96% yield, including Et3GeGePh3 which was isolated in
(57) Yokoyama, Y.; Hayakawa, M.; Azemi, T.; Mochida, K. J. Chem.
Soc., Chem. Commun. 1995, 2275.
(58) Azemi, T.; Yokoyama, Y.; Mochida, K. J. Organomet Chem. 2005,
690, 1588-1593.
(59) Glockling, F.; Hooton, K. A. J. Chem. Soc. 1962, 3509-3512.
(60) Glockling, F.; Hooton, K. A.; Kotz, J. C.; Laubengayer, A. W. Inorg.
Synth. 1966, 8, 31-34.
(61) Rivie`re, P.; Satge´, J. Bull. Soc. Chim. Fr. 1971, 3221-3231.
(62) Weidenbruch, M.; Grimm, F.-T.; Herrndorf, M.; Scha¨fer, A.; Peters,
K.; von Schnering, H. G. J. Organomet. Chem. 1988, 341, 335-343.
(63) Glockling, F. The Chemistry of Germanium; Academic Press:
London, 1969.
96% yield and Me3GeGeBun which was isolated in 59%
3
yield.57,58 This procedure thus can offer some synthetic advan-
tages over our method when certain organic substituents are
present.
The use of acetonitrile as the solvent is necessary for the
success of these reactions. Germanium amides are known to
react with acetonitrile resulting in R-germylated nitriles R3-
(64) Weinert, C. S. In ComprehensiVe Organometallic Chemistry III;
Crabtree, R. H., Mingos, D. M. P., Eds.; Elsevier: Oxford, 2006, in press.
(65) Lesbre, M.; Mazerolles, P.; Satge´, J. The Organic Compounds of
Germanium; Wiley-Interscience: London, 1971.
(66) Shibata, K.; Weinert, C. S.; Sita, L. R. Organometallics 1998, 17,
2241-2248.
(67) Bulten, E. J.; Noltes, J. G. Tetrahedron Lett. 1966, 4389-4392.

Preparation of Oligogermanes Via Hydrogermolysis
Organometallics, Vol. 25, No. 13, 2006 3213
Scheme 2
GeCH2CN, which contain a reactive Ge-C bond, and bisger-
mylated nitriles (R3Ge)2CHCN can also be formed as a
byproduct.68-70 The reactions are catalyzed by the addition of
small amounts of Lewis acids such as ZnCl2. To determine if
an intermediate such as R3GeCH2CN plays a role in the
(5 mol % based on Bu3GeCH2CN) of acetonitrile. Thus, the
formation of an intermediate R3GeCH2CN species from the
germanium amide and acetonitrile solvent appears to be a key
factor in the success of the Ge-Ge bond formation process,
and the -CH2CN moiety might thus serve as a useful functional
group in future investigations.
formation of Ge-Ge bonds, the reaction of Bun GeNMe2 with
3
1
Ph3GeH in acetonitrile-d3 solvent was monitored by H NMR
The permutations of reactions of organotin and organoger-
manium hydrides and organotin and organogermanium amides
spectroscopy, and the observed reaction pathway is shown in
Scheme 2. Initially, a solution of Bun GeNMe2 in CD3CN was
were investigated in four separate H NMR experiments (eqs
1
3
prepared which exhibited a sharp resonance at δ 2.45 ppm in
its 1H NMR spectrum and a peak at δ 41.5 ppm in its 13C NMR
spectrum arising from the amide group. After heating the sample
for 1 h at 90 °C, both of these features had nearly disappeared,
indicating that most of the amide had been converted to Bu3-
GeCD2CN. A resonance at δ 2.29 ppm was also clearly visible
due to the formation of DN(CH3)2. At this point 1 equiv of
Ph3GeH and a small amount of Me4Ge (ca. 5 mg as an internal
standard) were added to the tube. The Ge-H resonance at δ 5.64
ppm was integrated versus the peak for Me4Ge at δ 0.14 ppm
to monitor the progress of the reaction. The Ge-H resonance at
δ 5.64 ppm had decreased slightly in intensity after heating the
3-6) in order to obtain a qualitative understanding of the relative
reactivities in these systems. Formation of the Sn-Sn bond was
1
sample for 3 h at 90 °C, and features in both the H and 13C
complete within 2 h (eq 3), while formation of the Ge-Sn bond
using the reactants shown in eq 4 was complete within 4 h.
However, complete formation of the Ge-Sn bond shown in eq
5 took 36 h, and formation of the digermane 3 required a
reaction time of 48 h (eq 6). These results agree with those
previously reported, which indicate that the Ge-N bond is
stronger than the Sn-N bond65,72 and that the Ge-H bond is
less reactive than the Sn-H bond in reactions with species
containing E-N bonds (E ) Ge, Sn, Pb).61,72-75 Thus, both of
these factors result in a more sluggish reaction for the formation
of Ge-Ge bonds versus reactions resulting in Sn-Sn bond
formation. Additionally, the reactions involving the tin amides
(eqs 3 and 5) also proceed to completion in toluene-d8 and
therefore involve hydrostannolysis of a Sn-N bond rather than
a Sn-C bond.
The X-ray crystal structures of digermanes 1 and 2 were
determined and ORTEP diagrams are shown in Figures 1 and
2, while selected bond distances and angles are collected in
Tables 1 and 2, respectively. Compound 1 contains two
crystallographically independent molecules in the unit cell which
have an average Ge-Ge distance of 2.4212(8) Å. The three
phenyl and three ethyl substituents in compound 2 are symmetry
related, and the Ge-Ge distance is 2.4253(7) Å. These distances
can be compared to those in other linear oligogermanes
including the related derivatives Me3GeGePh3, Ph3GeGePh3, and
But3GeGeBut3, which have Ge-Ge bond lengths of 2.418(1),76
2.437(2),39 and 2.710(1) Å (average between two molecules),62
respectively. Germanium-germanium bond lengths are depend-
ent on the size and electron-withdrawing or -donating ability
of the attached organic groups, and thus both the hexaphenyl
NMR spectra indicated that some 1 was being formed. The
progress of the reaction was monitored at regular intervals,
which showed that Ph3GeH was being continuously consumed
and compound 1 was being formed. After 20 h approximately
50% of the Ph3GeH had reacted, and after 50 h only a small
1
amount (ca. 5%) remained. Both the H and 13C NMR spectra
of the sample clearly indicated the clean formation of 1.
To fully ascertain if a R-germylated nitrile is a crucial
intermediate in the Ge-Ge bond forming process, we prepared
Bu3GeCH2CN from LiCH2CN 71 and Bu3GeCl (eq 1). The 13
C
NMR spectrum of this species contains a broadened resonance
at δ 16.0 ppm arising from the R-carbon of the -CH2CN group,
while a signal for the cyano carbon appears at δ 68.1 ppm. A
sample containing Bu3GeCH2CN and 1 equiv of Ph3GeH in
CD3CN was prepared and the reaction was monitored by NMR
spectroscopy. The initial 1H and 13C spectra taken after
approximately 10 min exhibited evidence of an immediate
reaction, as signals for 1 were already clearly visible. Heating
the sample for 50 min at 90 °C resulted in complete consumption
of Ph3GeH and quantitative formation of 1. Compound 1 was
also obtained on a preparative scale under these conditions and
was isolated in 89% yield (eq 2). The use of acetonitrile is again
essential for this reaction, as Bu3GeCH2CN does not react with
Ph3GeH in toluene even in the presence of a catalytic amount
(72) Creemers, H. M. J. C.; Noltes, J. G. J. Organomet. Chem. 1967, 7,
237-247.
(73) Neumann, W. P.; Ku¨hlein, K. Tetrahedron Lett. 1966, 7, 3419-
3421.
(68) Rivie`re-Baudet, M.; Rivie`re, P. J. Organomet. Chem. 1976, 116,
C49-C52.
(69) Rivie`re-Baudet, M. Main Group Met. Chem. 1995, 18, 353-385.
(70) Lappert, M. F.; Power, P. P.; Sanger, A. R.; Srivatava, R. C. Metal
and Metalloid Amides; Ellis Horwood Ltd.: West Sussex, England, 1980.
(71) Ohlsson, B.; Ullenius, C.; Jagner, S.; Grivet, C.; Wenger, E.; Ku¨ndig,
E. P. J. Organomet. Chem. 1989, 365, 243-267.
(74) Neumann, W. P.; Schneider, B.; Sommer, R. Liebigs Ann. Chem.
1966, 692, 1-11.
(75) Bochkarev, M. N.; Vyazankin, N. S.; Bochkarev, L. N.; Razuvaev,
G. A. J. Organomet. Chem. 1976, 110, 149-157.
(76) Pa´rka´nyi, L.; Ka´lma´n, A.; Sharma, S.; Nolen, D. M.; Pannell, K.
H. Inorg. Chem. 1994, 33, 180-182.

3214 Organometallics, Vol. 25, No. 13, 2006
Subashi et al.
Table 1. Selected Bond Distances (Å) and Angles (deg) for
the Two Crystallographically Independent Molecules of
Bu3GeGePh3 (1)
1a
1b
average
Ge(1)-Ge(2)
Ge(1)-C(21)
Ge(1)-C(31)
Ge(1)-C(41)
Ge(2)-C(1)
Ge(2)-C(5)
Ge(2)-C(9)
2.415(8) Ge(1′)-Ge(2′)
1.956(4) Ge(1′)-C(21′)
1.956(4) Ge(1′)-C(31′)
1.953(4) Ge(1′)-C(41′)
1.921(5) Ge(2′)-C(1′)
1.902(5) Ge(2′)-C(5′)
2.006(7) Ge(2′)-C(9′)
2.4270(8) 2.4212(8)
1.954(4) 1.955(4)
1.955(4) 1.956(4)
1.952(4) 1.953(4)
1.947(4) 1.934(4)
1.941(5) 1.922(5)
1.987(6) 1.997(6)
C(21)-Ge(1)-C(31) 107.2(2) C(21′)-Ge(1′)-C(31′) 106.8(2) 107.0(2)
C(21)-Ge(1)-C(41) 107.8(2) C(21′)-Ge(1′)-C(41′) 108.5(2) 108.2(2)
C(31)-Ge(1)-C(41) 108.3(2) C(31′)-Ge(1′)-C(41′) 106.9(2) 107.6(2)
C(21)-Ge(1)-Ge(2) 115.0(1) C(21′)-Ge(1′)-Ge(2′) 111.7(1) 113.4(1)
C(31)-Ge(1)-Ge(2) 111.3(1) C(31′)-Ge(1′)-Ge(2′) 110.3(1) 110.8(1)
C(41)-Ge(1)-Ge(2) 107.1(1) C(41′)-Ge(1′)-Ge(2′) 112.3(1) 109.7(1)
C(1)-Ge(2)-C(5)
C(1)-Ge(2)-C(9)
C(5)-Ge(2)-C(9)
113.8(3) C(1′)-Ge(2′)-C(5′)
105.9(3) C(1′)-Ge(2′)-C(9′)
107.3(4) C(5′)-Ge(2′)-C(9′)
109.9(2) 111.9(2)
106.8(2) 106.4(2)
107.5(3) 107.4(3)
Figure 1. ORTEP diagram of one of the crystallographically
independent molecules of Bu3GeGePh3 (1a). Thermal ellipsoids are
drawn at 50% probability.
C(1)-Ge(2)-Ge(1) 110.0(2) C(1′)-Ge(2′)-Ge(1′) 108.9(1) 109.5(1)
C(5)-Ge(2)-Ge(1) 112.5(2) C(5′)-Ge(2′)-Ge(1′) 112.3(1) 112.4(1)
C(9)-Ge(2)-Ge(1) 106.9(2) C(9′)-Ge(2′)-Ge(1′) 111.3(2) 109.1(2)
Table 2. Selected Bond Distances (Å) and Angles (deg) for
Et3GeGePh3 (2)
Ge(1)-Ge(2)
Ge(1)-C(1)
Ge(2)-C(7)
2.4253(7)
1.954(2)
1.959(2)
C(1)-Ge(1)-C(1_2)
C(7)-Ge(2)-C(7_2)
C(1)-Ge(1)-Ge(2)
Ge(1)-Ge(2)-C(7)
107.78(7)
109.75(9)
111.11(7)
109.19(9)
of these resonances can be used to monitor the progress of
1
subsequent reactions using H NMR spectroscopy.
Germanes 5a-c were each reacted with a slight excess of
Ph3GeH in a sealed Schlenk tube using acetonitrile as the solvent
over 48 h at 90 °C to furnish the digermanes 6a-c in yields of
75% (6a), 76% (6b), and 92% (6c) after purification by
Kugelrohr distillation to remove any unreacted Ph3GeH (Scheme
4). Care must be taken when purifying 6a in this fashion, as it
is substantially more volatile than 6b or 6c and can codistill
with the Ph3GeH. These digermanes have been characterized
by NMR (1H and 13C) spectroscopy and elemental analysis. The
1H NMR spectrum of 6a exhibits a triplet at δ 3.44 ppm (J )
7.8 Hz) and a quartet at δ 3.14 ppm (J ) 6.9 Hz) arising from
the protons of the methylene groups bound to the oxygen atom
of the ethoxyethyl substituent. For 6b and 6c these protons give
rise to triplets at δ 3.51 ppm (J ) 7.2 Hz) (6b) and δ 3.59 ppm
(J ) 7.8 Hz) (6c) and quartets at δ 3.18 ppm (J ) 7.2 Hz) (6b)
and δ 3.03 ppm (J ) 6.9 Hz) (6c).
In a method similar to that used by Sita for the related tin
species,8 compounds 6a and 6b could be converted to the
hydride-terminated digermanes 7a and 7b by reaction with di-
isobutylaluminum hydride (DIBAL-H), but more vigorous
reaction conditions were required in the case of germanium.
Although oligostannanes can be converted to the corresponding
hydrides at room temperature in ca. 1 h,8 using this reagent for
the preparation of the germanium hydrides in benzene required
a reflux period of 12 h. To obtain the hydrides in pure form,
the crude product mixtures were passed through a short silica
gel column using benzene as the eluent in order to remove any
aluminum-containing byproducts. Often subsequent distillation
was required to fully remove these contaminants. In addition,
the phenyl derivative 6c could not be converted to the
corresponding hydride 7c using DIBAL-H presumably due to
steric interactions between the phenyl substituents on the
digermane and the isobutyl groups of Bui2AlH. The yields of
Figure 2. ORTEP diagram of Et3GeGePh3 (2). Thermal ellipsoids
are drawn at 50% probability.
and hexa-tert-butyl derivatives are expected to exhibit longer
Ge-Ge bonds compared to Me3GeGePh3 and compounds 1 and
2 due to the presence of the more bulky Ph or But ligands. The
alkyl substituents in the three latter species all have the same
relative size and electron-donating characteristics and thus all
three digermanes exhibit similar Ge-Ge bond distances, as
expected.
To systematically construct chains of germanium atoms, we
prepared the three synthons 5a-c in good overall yields via
the three-step process shown in Scheme 3. Monochlorination
of the germanium dihydride reagents R2GeH2 proceeded in high
yield.77 These R2GeHCl reagents were used to hydrogermylate
ethyl vinyl ether to yield the chlorides 4a-c, which were
subsequently reacted with LiNMe2 to give the amide synthons
5a-c. The overall yields for the germanium amides relative to
the starting materials R2GeHCl are 82% (5a), 75% (5b), and
57% (5c), and the protons of the -NMe2 groups of these
products exhibit characteristic 1H NMR features at δ 2.57 ppm
(5a), δ 2.60 ppm (5b), and δ 2.78 ppm (5c). The disappearance
(77) Ohshita, J.; Toyoshima, Y.; Iwata, A.; Tang, H.; Kunai, A. Chem.
Lett. 2001, 886-887.

Preparation of Oligogermanes Via Hydrogermolysis
Organometallics, Vol. 25, No. 13, 2006 3215
Scheme 3
Scheme 4
7a (69%) and 7b (52%) are moderate, and we have attempted
to circumvent this difficulty by employing LiBH4 or LiBHEt3
as the hydride transfer reagent. However, neither of these
reagents served for the preparation of 7a-c under various
experimental conditions including refluxing in benzene, toluene,
or THF for 48 h.
The hydrides 7a and 7b exhibit characteristic Ge-H stretch-
ing bands at 1996 cm-1 (7a) and 2036 cm-1 (7b) in their
infrared spectra similar to other digermane hydrides.78 They also
exhibit a pentet in their 1H NMR spectra arising from the
terminal hydride at δ 4.91 ppm (J ) 3.0 Hz) (7a) and δ 4.40
ppm (J ) 3.6 Hz) (7b), which is broadened in each case due to
coupling with the highly quadupolar 73Ge nucleus. The complete
conversion of the starting digermanes 6a and 6b to the hydrides
7a and 7b is indicated by the absence of the methylene features
of the ethoxyethyl groups described above.
Compounds 7a and 7b were reacted with an additional
equivalent of the corresponding germanium amides 5a or 5b to
provide the trigermanes 8a and 8b in respective yields of 90%
and 94% (Scheme 4), which were also characterized by NMR
(1H and 13C) spectroscopy and elemental analysis. The 1H NMR
spectrum of 8a exhibits characteristic features at δ 3.28 ppm
(t, J ) 6.6 Hz) and δ 3.14 ppm (q, J ) 6.9 Hz) for the protons
of the methylene groups bound to oxygen in the ethoxyethyl
substituent, while for 8b these features appear at δ 3.51 ppm
(t, J ) 7.5 Hz) and δ 3.18 ppm (q, J ) 6.9 Hz). The chemical
shifts of these resonances are similar to those of the digermanes
6a and 6b.
contained in the ethyl or butyl side groups as well as the terminal
methyl group and the R-methylene group of the ethoxyethyl
substituent. The integrated ratio of the alkyl versus the aromatic
1
regions of the H NMR spectra of 6a is almost exactly 1:1 as
expected, while that of 8a is 1.61:1, which is close to the
predicted value of 1.67:1. A similar result was found for 6b
(1.57:1, calculated 1.53:1) and 8b (2.80:1, calculated 2.73:1).
Product compositions also were confirmed by 13C NMR
spectroscopy and by elemental analysis.
The trigermanes 8a and 8b were converted to the correspond-
ing hydrides 9a and 9b again in modest yields (9a, 41%; 9b,
33%), as shown in Scheme 4 and exhibit characteristic infrared
1
(νGe-H ) 1996 cm-1 (9a), 2000 cm-1 (9b)) and H NMR (δ
4.31 ppm (J ) 3.2 Hz) (9a), δ 4.91 ppm (J ) 3.0 Hz) (9b))
spectral features. Purification of these species required first
washing the crude products on a short silica column followed
by vacuum distillation of the resulting material. Washing on a
second silica column was required to obtain 9a and 9b in pure
1
form (as shown by H NMR spectroscopy) and this extensive
purification is likely the cause of the diminished yields of these
products. The hydrides 9a and 9b were subsequently employed
for the preparation of the tetragermanes 10a and 10b in yields
of 97% and 85% (Scheme 4), respectively, and the identities
of these compounds were again confirmed by integration of their
1H NMR spectra, giving alkyl:aromatic ratios of 2.32:1 for 10a
(calculated value 2.33:1) and 3.99:1 for 10b (calculated value
3.93:1). Both tetragermanes were further characterized by 13C
NMR spectroscopy and elemental analysis.
The overall yields of the tri- and tetragermanes can be
improved if the intermediate hydrides are not isolated but rather
reacted directly with additional equivalents of the germanium
amides 5. For example, reaction of the trigermane 8b with a
slight excess of DIBAL-H in refluxing benzene for 12 h
followed by removal of the solvent and treatment of the resulting
crude product with 1 equiv of 5b in CH3CN produced the
The composition of the products can be confirmed by
integration of the aromatic versus the alkyl region in the H
NMR spectra of both 6a,b and 8a,b. For each class of
compound, the alkyl region includes resonances for all protons
1
(78) Marchand, A.; Gerval, P. J. Organomet. Chem. 1978, 162, 365-
387.

3216 Organometallics, Vol. 25, No. 13, 2006
Subashi et al.
Et3GeNMe2,85 Bu3GeNMe2,86 Bu3GeGePh3,78,87,88 Et3GeGePh3,78,88,89
and Bu3GeGeMe387 have been reported but were not fully charac-
terized, and their complete characterization is described below.
NMR spectra were recorded using a Varian Gemini 2000 instrument
operating at 300 MHz (1H) or 75.5 MHz (13C) and are referenced
to the solvent resonances. Infrared spectra were recorded using a
Perkin-Elmer 2000 FTIR system. UV/visible spectra were obtained
using a Hewlett-Packard Agilent UV/visible spectroscopy system.
Elemental analyses were conducted by Desert Analytics.
Synthesis of Et3GeNMe2. A flask was charged with Et3GeCl
(2.302 g, 11.79 mmol) dissolved in benzene (30 mL). To this was
added solid LiNMe2 (0.789 g, 15.5 mmol). The resulting suspension
was stirred for 12 h and then filtered through Celite to yield a clear
solution. The volatiles were removed in Vacuo to yield a slightly
turbid oil, which was distilled using a Kugelrohr oven (oven temp
) 100 °C at 0.11 Torr) to yield Et3GeNMe2 (1.371 g, 57%) as a
clear oil. 1H NMR (C6D6, 25 °C): δ 2.58 (s, 6H, GeN(CH3)2), 1.07
(t, J ) 8.4 Hz, 9H, GeCH2CH3), 0.80 (m, J ) 8.4 Hz, 6H, GeCH2-
CH3) ppm. 13C NMR (C6D6, 25 °C): δ 41.4 (-N(CH3)2), 9.3 (Ge-
(CH2CH3)3), 4.6 (Ge(CH2CH3)3) ppm.
Synthesis of Bu3GeNMe2. A flask was charged with 1.583 g
(5.666 mmol) of Bu3GeCl dissolved in benzene (30 mL). To this
was added solid LiNMe2 (0.354 g, 6.94 mmol). The resulting
suspension was stirred for 12 h and then filtered through Celite to
yield a clear solution. The volatiles were removed in Vacuo to yield
a slightly turbid oil, which was distilled using a Kugelrohr oven
(oven temp ) 105 °C at 0.09 Torr) to yield Bu3GeNMe2 (1.469 g,
90%) as a clear oil. 1H NMR (C6D6, 25 °C): δ 2.62 (s, 6H, GeN-
(CH3)2), 1.52-1.30 (m, 12H, GeCH2CH2CH2CH3), 0.93 (t, J )
7.2 Hz, 9H, GeCH2CH2CH2CH3), 0.89 (m, 6H, GeCH2) ppm. 13C
NMR (C6D6, 25 °C): δ 41.5 (-N(CH3)2), 27.4, 26.9, 14.1 (butyl
group carbons), 13.2 (-CH2CH2CH2CH3) ppm. Anal. Calcd for
C14H33GeN: C, 58.38; H, 11.55. Found: C, 58.28; H, 11.79.
Synthesis of Bu3Ge-GePh3 (1). A flask was charged with 0.770
g (2.67 mmol) of Bu3GeNMe2, which was dissolved in acetonitrile
(15 mL). To this was added a solution of Ph3GeH (0.864 g, 2.83
mmol) in acetonitrile (10 mL). The resulting solution was refluxed
under N2 for 48 h and allowed to cool, and the volatiles were
removed in Vacuo. Kugelrohr distillation (oven temp ) 180 °C at
0.10 Torr) of the crude material to remove excess Ph3GeH yielded
1 (1.21 g, 83%) as a white solid. 1H NMR (C6D6, 25 °C): δ 7.72-
7.64 (m, 6H, meta-H), 7.24-7.16 (m, 9H, ortho-H and para-H),
1.52-1.39 (m, 6H, GeCH2), 1.27 (sext, J ) 7.8 Hz, 6H, GeCH2-
CH2CH2CH3), 1.21-1.15 (m, 6H, GeCH2CH2CH2CH3), 0.81 (t, J
) 6.9 Hz, 9H, GeCH2CH2CH2CH3) ppm. 13C NMR (C6D6, 25
°C): δ 139.7, 135.7, 128.7, 128.6 (aromatic carbons), 28.8, 26.8,
14.5, 13.8 (butyl group carbons) ppm. Anal. Calcd for C30H42Ge2:
C, 65.77; H, 7.73. Found: C, 65.74; H, 7.80.
tetragermane 10b in 75% yield, a substantial improvement over
the 28% overall yield achieved when the hydride 9b was isolated
and purified. Excess DIBAL-H and the byproducts formed in
the hydride transfer reaction do not interfere with the hydrog-
ermolysis reaction, and this method thus could be useful for
extension of the Ge-Ge chain length beyond four germanium
atoms.
The tetragermanes 10a and 10b exhibit observable absorbance
maxima in their electronic spectra that appear as shoulders on
the CH3CN solvent peak at 235 nm (10a) and 241 nm (10b)
arising from the σ f σ* transition. The related spectra for the
di- (6a,b) and trigermanes (8a,b) as well as their respective
hydrides must have absorbance maxima that are not observed
above the solvent cutoff. The positions of λmax for 10a and 10b
are similar to those of other related species including the
tetragermane Et3Ge(GeEt2)2GeEt3 (λmax ) 234 nm) and the
hexagermane Et3Ge(GeEt2)4GeEt3 (λmax ) 258 nm).4 The related
tin-containing congeners exhibit a more substantial red shift of
their absorbance maxima, as illustrated for the related tetra-
stannane Bu3Sn(SnBu2)2SnOCH2CH2OEt, which has a λmax at
ca. 275 nm, and the hexastannane Bu3Sn(SnBu2)4SnCH2CH2-
OEt, which exhibits a λmax at 310 nm.8 The absorbance maxima
for related polygermanes79-83 such as poly(phenylmethyl)-
germane (Mw ) 6900, λmax ) 330 nm)82 or poly(dibutyl)-
germane (Mw ) 14000, λmax ) 325 nm)79 are also not as
significantly red shifted as their shorter-chain oligostannane
analogues. Further investigations are required to ascertain the
reason for this difference, although these data suggest that the
σ f σ* transition in oligostannanes occurs at a lower energy
than that of the germanium derivatives.
In conclusion, we have prepared and characterized two series
of oligogermanes by sequential chain buildup and have used
germanium amides and germanium hydrides for the formation
of Ge-Ge bonds. This reaction requires the use of acetonitrile
as the solvent and proceeds via the hydrogermolysis of a reactive
R-germylated nitrile intermediate. The methods used in this
study offer several advantages over previously employed
synthetic techniques including generally improved yields, the
formation of discrete molecules rather than product mixtures,
and direct control over the substituents attached to the Ge-Ge
backbone since the germanium atoms are added one at a time.
This method therefore will facilitate the preparation of oligomers
with diverse substitution patterns, which in turn permits the
tailoring of molecules that might exhibit certain optical and
electronic properties.
Experimental Section
Synthesis of Et3Ge-GePh3 (2). To a solution of Et3GeNMe2
(0.417 g, 2.00 mmol) in acetonitrile (15 mL) in a Schlenk tube
was added Ph3GeH (0.0.637 g, 2.10 mmol) in acetonitrile (15 mL).
The tube was sealed with a Teflon plug, and the reaction was heated
at 85 °C for 48 h. The solution was transferred to a Schlenk flask,
and the volatiles were removed in Vacuo. The crude product was
distilled in a Kugelrohr oven (oven temp ) 100 °C, P ) 0.05 Torr)
to remove excess Ph3GeH to yield 2 as a white solid (0.247 g,
General Considerations. All manipulations were carried out
under an inert atmosphere using standard Schlenk, glovebox, and
syringe techniques.84 Solvents were dried using a Glass Contour
solvent purification system. The starting materials Et3GeCl, Bu3-
GeCl, and Me3GeH were purchased from Gelest and ethyl vinyl
ether, AIBN, Ph3GeH, and LiNMe2 were purchased from Aldrich
and used without further purification. The hydrochlorides R2GeHCl
were prepared via the method of Kunai et al.77 The compounds
1
84%). H NMR (C6D6, 25 °C): δ 7.64-7.61 (m, 6H, meta-H),
7.23-7.16 (m, 9 H, ortho-H and para-H), 1.03 (m, 15H, Ge-
(CH2CH3)3) ppm. 13C NMR (C6D6, 25 °C): δ 139.2, 135.6, 128.7,
(79) Okano, M.; Takeda, K.; Toriumi, T.; Hamano, H. Electrochim. Acta
1998, 44, 659-666.
(80) Motonaga, M.; Nakashima, H.; Katz, S.; Berry, D. H.; Imase, T.;
Kawauchi, S.; Watanabe, J.; Fujiki, M.; Koe, J. R. J. Organomet. Chem.
2003, 685, 44-50.
(85) Highsmith, R. E.; Sisler, H. H. Inorg. Chem. 1969, 8, 1029-1032.
(86) Rijkens, F.; Janssen, M. J.; van der Kerk, G. J. M. Recl. TraV. Chim.
Pays-Bas 1965, 84, 1597-1609.
(87) Bulten, E. J.; Noltes, J. G. Recl. TraV. Chim. Pays-Bas 1972, 91,
1041-1056.
(88) Duffaut, N.; Dunogues, J.; Calas, R.; Gerval, J.; Rivie`re, P.; Satge´,
J.; Cazes, A. J. Organomet Chem. 1978, 149, 57-63.
(89) Rivie`re, P.; Satge´, J.; Dousse, G.; Rivie`re-Baudet, M.; Couret, C.
J. Organomet. Chem. 1974, 72, 339-350.
(81) Huo, Y.; Berry, D. H. Chem. Mater. 2005, 17, 157-163.
(82) Katz, S. M.; Reichl, J. A.; Berry, D. H. J. Am. Chem. Soc. 1998,
120, 9844-9849.
(83) Kobayashi, S.; Cao, S. Chem. Lett. 1993, 1385-1388.
(84) Shriver, D. F.; Drezdzon, M. A. The Manipulation of Air-SensitiVe
Compounds, 2nd ed.; John Wiley and Sons: New York, 1986.

Preparation of Oligogermanes Via Hydrogermolysis
Organometallics, Vol. 25, No. 13, 2006 3217
128.6 (aromatic carbons), 10.2, 6.1 (ethyl group carbons) ppm. Anal.
Calcd for C24H30Ge2: C, 62.16; H, 6.52. Found: C, 61.96; H, 6.61.
(0.509 g, 9.98 mmol). The resulting suspension was stirred at room
temperature for 7 h and was then filtered through Celite. The
volatiles were removed from the filtrate in Vacuo to yield 2.25 g
(92%) of 5a as a clear oil. 1H NMR (C6D6, 25 °C): δ 3.50 (t, J )
7.5 Hz, 2H, GeCH2CH2O), 3.29 (q, J ) 7.2 Hz, 2H, q, -OCH2-
CH3), 2.57 (s, 6H, -N(CH3)2), 1.24 (t, J ) 7.2 Hz, 3H,
-OCH2CH3), 1.17-1.05 (m, 6H, (CH3CH2)2Ge and GeCH2CH2-
O-), 0.87 (t, J ) 7.2 Hz, 6H, Ge(CH2CH3)2) ppm. 13C NMR (C6D6,
25 °C): δ 67.8 (-OCH2CH3), 65.8 (GeCH2CH2O-), 41.4
(-N(CH3)2), 15.5, 14.2, 8.8, 5.6 (aliphatic carbons) ppm. Anal.
Calcd for C10H25GeNO: C, 48.44; H, 10.16. Found: C, 47.55; H,
10.51.
Synthesis of Bu3Ge-GeMe3 (3). A solution of Me3GeH (0.113
g, 0.952 mmol) in acetonitrile (10 mL) was added to a solution of
Bu3GeNMe2 (0.226 g, 0.785 mmol) in acetonitrile (10 mL) in a
Schlenk tube. The tube was sealed with a Teflon plug, and the
reaction mixture was heated to 85 °C for 48 h. The solution was
transferred to a Schlenk flask, and the volatiles were removed in
Vacuo. The crude product was distilled in a Kugelrohr oven (oven
temp ) 85 °C, P ) 0.05 Torr) to remove excess staring material
1
to yield 3 as a colorless oil (0.244 g, 86%). H NMR (C6D6, 25
°C): δ 1.58-1.51 (m, 6H, GeCH2CH2CH2CH3), 1.42 (pent, J )
5.7 Hz, 6H, GeCH2CH2CH2CH3), 0.96 (m, 15H, GeCH2CH2CH2-
CH3 and GeCH2CH2CH2CH3), 0.26 (s, 9H, GeCH3) ppm. 13C NMR
(C6D6, 25 °C): δ 27.0, 26.8, 18.2, 14.0 (butyl groups), 1.4 (GeCH3)
ppm. Anal. Calcd for C15H36Ge2: C, 49.81; H, 10.03. Found: C,
50.11; H, 10.08.
Synthesis of Bu2Ge(NMe2)CH2CH2OEt (5b). To a solution of
4b (1.324 g, 4.482 mmol) in benzene (35 mL) was added solid
lithium dimethylamide (0.234 g, 4.59 mmol). The resulting suspen-
sion was stirred 8 h, followed by filtration through Celite to yield
a clear solution. Removal of the volatiles in Vacuo yielded 5b (1.42
g, 92%) as a clear oil. 1H NMR (C6D6, 25 °C): δ 3.54 (t, J ) 7.8
Hz, 2H, GeCH2CH2O), 3.31 (q, J ) 6.9 Hz, 2H, OCH2CH3), 2.60
(s, 6H, N(CH3)2), 1.53-1.26 (m, 10 H), 1.43 (t, J ) 6.9 Hz, 3H,
OCH2CH3), 0.92 (t, J ) 6.9 Hz, 6H, GeCH2CH2CH2CH3), 0.89
(m, 4H, GeCH2CH2CH2CH2CH3) ppm. 13C NMR (C6D6, 25 °C):
δ 68.0 (-OCH2CH3), 65.8 (GeCH2CH2O-), 41.4 (-N(CH3)2),
27.3, 26.9, 15.6, 15.0, 14.0, 13.6 (aliphatic carbons) ppm. Anal.
Calcd for C14H33GeNO: C, 55.31; H, 10.94. Found: C, 54.91; H,
11.00.
Synthesis of Et2Ge(Cl)CH2CH2OEt (4a). To a solution of Et2-
GeHCl (1.90 g, 11.4 mmol) in benzene (30 mL) in a Schlenk tube
was added ethyl vinyl ether (1.35 mL, 13.7 mmol) via syringe. A
solution of AIBN (0.038 g, 0.23 mmol) in benzene (2 mL) was
added to the reaction mixture. The tube was sealed with a Teflon
plug and heated at 85 °C for 18 h. The solution was transferred to
a Schlenk flask, and the volatiles were removed in Vacuo to yield
2.41 g (89%) of 4a as a clear oil. 1H NMR (C6D6, 25 °C): δ 3.33
(t, J ) 6.6 Hz, 2H, -GeCH2CH2O), 3.10 (q, J ) 7.2 Hz, 2H,
-OCH2CH3), 1.41 (t, J ) 7.2 Hz, 3H, -OCH2CH3), 1.16-1.04
(m, 6H, (CH3CH2)2Ge and GeCH2CH2O-), 0.97 (t, J ) 6.6 Hz,
6H, Ge(CH2CH3)2) ppm. 13C NMR (C6D6, 25 °C): δ 66.8 (-OCH2-
CH3), 66.0 (GeCH2CH2O-), 20.2, 15.2, 12.1, 8.2 (aliphatic carbons)
ppm. Anal. Calcd for C8H19ClGeO: C, 40.15; H, 8.00. Found: C,
39.25; H, 8.10.
Synthesis of Ph2Ge(NMe2)CH2CH2OEt (5c). To a solution of
4c (0.493 g, 1.47 mmol) in benzene (25 mL) was added solid
LiNMe2 (0.093 g, 1.8 mmol). The resulting suspension was stirred
at room temperature for 15 h and was then filtered through Celite.
The volatiles were removed from the filtrate in Vacuo to yield 0.436
g (86%) of 5c as a clear oil. 1H NMR (C6D6, 25 °C): δ 7.70-7.67
(m, 4H, meta-H), 7.21-7.17 (m, 6H, ortho-H and para-H), 3.58
(t, J ) 7.8 Hz, 2H, GeCH2CH2O), 3.10 (q, J ) 6.9 Hz, 2H, q,
-OCH2CH3), 2.78 (s, 6H, -N(CH3)2), 1.89 (t, J ) 7.8 Hz, 2H,
-GeCH2CH2O-), 1.00 (t, J ) 6.9 Hz 3H, OCH2CH3) ppm. 13C
NMR (C6D6, 25 °C): δ 136.9, 134.9, 129.3, 128.3 (aromatic
carbons), 67.2 (-OCH2CH3), 65.7 (GeCH2CH2O-), 41.4
(-N(CH3)2), 15.8, 15.3 (aliphatic carbons) ppm. Anal. Calcd for
C18H25GeNO: C, 62.85; H, 7.32. Found: C, 63.01; H, 7.54.
Synthesis of Bu2Ge(Cl)CH2CH2OEt (4b). To a solution of Bu2-
GeHCl (1.28 g, 5.74 mmol) in benzene (20 mL) in a Schlenk tube
was added ethyl vinyl ether (1.00 mL, 10.2 mmol) via syringe. A
solution of AIBN (0.016 g, 0.097 mmol) in benzene (4 mL) was
added to the reaction mixture. The tube was sealed with a Teflon
plug and heated at 85 °C for 18 h. The solution was transferred to
a Schlenk flask, and the volatiles were removed in Vacuo to yield
1.40 g (82%) of 4b as a clear oil. 1H NMR (C6D6, 25 °C): δ 3.41
(t, J ) 7.2 Hz, 2H, -GeCH2CH2O), 3.15 (q, J ) 6.9 Hz, 2H,
-OCH2CH3), 1.58-1.49 (m, 4H, GeCH2CH2CH2CH3), 1.47 (t, J
) 6.9 Hz, 4H, GeCH2CH2CH2CH3), 1.32 (sext, J ) 7.2 Hz, 4H,
GeCH2CH2CH2CH3) 1.17-1.11 (m, 2H, GeCH2CH2O-), 1.01 (t,
J ) 6.9 Hz, 3H, -OCH2CH3), 0.89 (t, J ) 7.2 Hz, 6H, GeCH2-
CH2CH2CH3) ppm. 13C NMR (C6D6, 25 °C): δ 66.9 (-OCH2-
CH3), 66.1 (GeCH2CH2O-), 26.6, 26.1, 21.1, 20.0, 15.3, 13.8
(aliphatic carbons) ppm. Anal. Calcd for C12H27ClGeO: C, 48.79;
H, 9.21. Found: C, 48.13; H, 8.74.
Synthesis of Ph3GeGe(Et2)CH2CH2OEt (6a). To a solution of
5a (0.762 g, 3.07 mmol) in acetonitrile (15 mL) in a Schlenk tube
was added Ph3GeH (0.945 g, 3.10 mmol) in acetonitrile (10 mL).
The tube was sealed with a Teflon stopper, and the reaction mixture
was heated at 90 °C for 36 h. The solution was transferred to a
Schlenk flask, and the volatiles were removed in Vacuo, yielding a
pale yellow oil. Kugelrohr distillation of the crude product afforded
1
1.179 g (75%) of 6a as a clear oil. H NMR (C6D6, 25 °C): δ
7.66-7.60 (m, 6H, aromatics), 7.24-7.14 (m, 9H, aromatics), 3.44
(t, J ) 7.8 Hz, 2H, GeCH2CH2O), 3.14 (q, J ) 6.9 Hz, 2H, -OCH2-
CH3), 1.49 (t, J ) 6.9 Hz, 3H, -OCH2CH3), 1.17-1.01 ppm (m,
Synthesis of Ph2Ge(Cl)CH2CH2OEt (4c). To a solution of Ph2-
GeHCl (0.590 g, 1.82 mmol) in benzene (15 mL) in a Schlenk
tube was added ethyl vinyl ether (0.20 mL, 2.0 mmol) via syringe.
A solution of AIBN (0.0090 g, 0.055 mmol) in benzene (2 mL)
was added to the reaction mixture. The tube was sealed with a
Teflon plug and heated at 85 °C for 24 h. The solution was
transferred to a Schlenk flask, and the volatiles were removed in
Vacuo to yield 0.493 g (66%) of 4c as a clear oil. 1H NMR (C6D6,
25 °C): δ 7.64-7.61 (m, 4H, meta-H), 7.18-7.07 (m, 6H, ortho-H
and para-H), 3.58 (t, J ) 7.5 Hz, 2H, -GeCH2CH2O), 3.10 (q, J
) 7.2 Hz, 2H, -OCH2CH3), 1.90 (t, J ) 7.5 Hz, 2H, GeCH2-
CH2O-), 1.00 (t, J ) 7.2 Hz, 3H, -OCH2CH3) ppm. 13C NMR
(C6D6, 25 °C): δ 136.7, 134.0, 130.2, 128.5 (aromatic carbons),
66.1 (-OCH2CH3), 66.0 (GeCH2CH2O-), 22.0, 15.0 (aliphatic
carbons) ppm. Anal. Calcd for C16H19ClGeO: C, 57.30; H, 5.71.
Found: C, 57.47; H, 5.81.
12H, (CH3CH2)2Ge, (CH3CH2)2Ge, and GeCH2CH2O-) ppm. 13
C
NMR (C6D6, 25 °C): δ 139.2, 135.7, 128.7, 128.6 (aromatic
carbons), 68.7 (-OCH2CH3), 65.7 (GeCH2CH2O-), 15.5, 15.4,
10.3, 7.2 (aliphatic carbons) ppm. Anal. Calcd for C26H34Ge2O:
C, 61.50; H, 6.75. Found: C, 61.18; H, 6.96.
Synthesis of Ph3Ge-Ge(Bu)2CH2CH2OEt (6b). To a solution
of 5b (0.633 g, 2.18 mmol) in acetonitrile (15 mL) was added Ph3-
GeH (0.670 g, 2.20 mmol) in acetonitrile (10 mL). The solution
was refluxed for 48 h, and the volatiles were removed in Vacuo to
yield a yellow oil. The material was distilled in a Kugelrohr oven
to remove the remaining Ph3GeH, and the pot residue was isolated
to yield 0.930 g (76%) of 6b as a pale yellow oil. 1H NMR (C6D6,
25 °C): δ 7.68-7.65 (m, 6H, aromatics), 7.24-7.14 (m, 9 H,
aromatics), 3.51 (t, J ) 7.2 Hz, 2H, GeCH2CH2OEt), 3.18 (q, J )
7.2 Hz, OCH2CH3), 1.56 (t, J ) 7.5 Hz, 2H, GeCH2CH2O), 1.49-
1.41 (m, 4H, aliphatics), 1.31-1.18 (m, 8H, aliphatics), 1.08 (t, J
Synthesis of Et2Ge(NMe2)CH2CH2OEt (5a). To a solution of
4a (2.36 g, 9.86 mmol) in benzene (35 mL) was added solid LiNMe2

3218 Organometallics, Vol. 25, No. 13, 2006
Subashi et al.
) 6.9 Hz, 3H, OCH2CH3), 0.80 (t, J ) 7.2 Hz, 6H, -(CH2)3CH3)
ppm.. 13C NMR (C6D6, 25 °C): δ 139.1, 135.7, 128.7, 128.5
(aromatic carbons), 68.9 (-OCH2CH3), 65.6 (GeCH2CH2O-), 28.7,
26.7, 16.2, 15.4, 14.9, 13.7 (aliphatic carbons) ppm. Anal. Calcd
for C30H42Ge2O: C, 63.90; H, 7.51. Found: C, 63.55; H, 7.48.
mL). The reaction mixture was sealed in a Schlenk tube equipped
with a Teflon plug and was heated at 85 °C for 48 h. The solution
was transferred to a Schlenk flask, and the volatiles were removed
in Vacuo. The crude product was distilled in a Kugelrohr oven (oven
temp ) 100 °C, P ) 0.08 Torr) for 3 h to remove excess 5b. Yield
of 8b ) 2.555 g (94%). 1H NMR (C6D6, 25 °C): δ 7.73-7.65 (m,
6H, aromatics), 7.23-7.12 (m, 9 H, aromatics), 3.51 (t, J ) 7.5
Hz, 2H, GeCH2CH2OEt), 3.18 (q, J ) 6.9 Hz, 2H, -OCH2CH3),
1.62-1.04 (m, 24 H, aliphatics), 0.98-0.72 (m, 17 H, aliphatics)
ppm. 13C NMR (C6D6, 25 °C): δ 139.1, 135.8, 128.7, 128.5
(aromatic carbons), 68.8 (-OCH2CH3), 65.7 (GeCH2CH2O-), 31.9,
28.8, 26.8, 20.0, 16.3, 15.0, 14.0, 13.8, 10.4, 7.1 (aliphatic carbons)
ppm. Anal. Calcd for C38H60Ge4O: C, 60.79; H, 8.05. Found: C,
60.43; H, 8.39.
Synthesis of Ph3Ge-Ge(Ph)2CH2CH2OEt (6c). To a solution
of 5c (1.511 g, 4.392 mmol) in acetonitrile (40 mL) was added
Ph3GeH (1.339 g, 4.391 mmol) in acetonitrile (25 mL). The solution
was refluxed for 48 h, and the volatiles were removed in Vacuo to
yield a yellow oil. The material was distilled in a Kugelrohr oven
to remove the remaining Ph3GeH, and the pot residue was isolated
to yield 2.443 g (92%) of 6c as a white solid. 1H NMR (C6D6, 25
°C): δ 7.64-7.52 (m, 10 H, meta-H), 7.13-7.02 (m, 15 H, ortho-
and para-H), 3.59 (t, J ) 7.8 Hz, 2H, GeCH2CH2O-), 3.03 (q, J
) 6.9 Hz, 2H, -OCH2CH3), 2.08 (q, J ) 7.8 Hz, 2H, GeCH2-
CH2O-), 0.95 (t, J ) 6.9 Hz, 3H, -OCH2CH3) ppm. H, 13C NMR
(C6D6, 25 °C): δ 138.4, 138.1, 135.9, 135.5, 129.0, 128.9, 128.6,
128.5 (aromatic carbons), 68.4 (-OCH2CH3), 65.6 (GeCH2CH2O-
), 17.6, 15.2 (aliphatic carbons) ppm. Anal. Calcd for C34H34-
Ge2O: C, 67.63; H, 5.67. Found: C, 67.37; H, 5.44.
Synthesis of Ph3GeGe(Et2)Ge(Et2)H (9a). A solution of 8a
(0.217 g, 0.340 mmol) in benzene (15 mL) was treated with a 1.0
M hexane solution of DIBAL-H (0.35 mL, 0.35 mmol), and the
mixture was refluxed under N2 for 18 h. The volatiles were removed
in Vacuo to yield a clear oil, which was washed on a silica column
(1 in. h × 1 in. dia) using benzene as the eluent (30 mL). The
benzene was removed in Vacuo, and the resulting oil was distilled
using a Kugelrohr oven (oven temp ) 115 °C, P ) 0.07 Torr) to
remove any remaining impurities for 3 h to yield 9a as a clear oil
Synthesis of Ph3GeGe(Et2)H (7a). To a solution of 6a (0.600
g, 1.18 mmol) in benzene (20 mL) was added a 1.0 M solution of
DIBAL-H in hexane (1.22 mL, 1.22 mmol). The solution was
refluxed for 36 h, and the volatiles were removed in Vacuo to yield
a pale yellow oil. The crude material was filtered through a 1 in.
× 1 in. silica gel column using 25 mL of a 9:1 benzene/acetonitrile
solution as the eluent to yield 0.357 g (69%) of 7a as a cloudy
white liquid after removal of the solvent. 1H NMR (C6D6, 25 °C):
δ 7.67-7.61 (m, 6H, aromatics), 7.23-7.16 (m, 9H, aromatics),
4.91 (pent, J ) 3.0 Hz, 1H, Ge-H), 1.07-1.01 (m, 10H, Ge-
(CH2CH3)2) ppm. 13C NMR (C6D6, 25 °C): δ 139.2, 135.7, 128.7,
128.6 (aromatic carbons), 10.2, 6.2 (aliphatic carbons) ppm. IR
(Nujol): 1996.1 cm-1 (νGe-H). Anal. Calcd for C22H26Ge2: C, 60.65;
H, 6.01. Found: C, 60.81; H, 6.42.
1
(0.079 g, 41%). H NMR (C6D6, 25 °C): δ 7.64-7.61 (m, 6H,
aromatics), 7.22-7.17 (m, 9H, aromatics), 4.31 (pent, J ) 3.2 Hz,
1 H, Ge-H), 1.03 (m, 20 H, aliphatics) ppm. (13C NMR?) IR
(Nujol): 1996.4 cm-1 (νGe-H). We were not able to obtain a
satisfactory elemental analysis for 9a.
Synthesis of Ph3GeGe(Bu2)Ge(Bu2)H (9b). A solution of 8b
(1.965 g, 2.61 mmol) in benzene (40 mL) was treated with a 1.0
M hexane solution of DIBAL-H (2.88 mL), and the mixture was
refluxed under N2 for 48 h. The volatiles were removed in Vacuo
to yield a clear oil, which was washed on a silica column (1 in. h
× 1 in. dia) using benzene as the eluent (45 mL). The benzene
was removed in Vacuo, and the resulting oil was distilled using a
Ku¨gelrohr oven (oven temp ) 110 °C, P ) 0.05 Torr) for 5 h to
Synthesis of Ph3Ge-Ge(Bu)2H (7b). To a solution of 6b (1.286
g, 2.280 mmol) in benzene (15 mL) was added a 1.0 M solution of
diisobutylaluminum hydride (2.5 mL, 2.5 mmol) via syringe. The
resulting solution was refluxed for 18 h. The volatiles were removed
in Vacuo to yield a clear viscous oil. The crude material was
dissolved in hexane (5 mL) and filtered through a short column (1
in.) of silica gel using 45 mL of hexane as the eluent. The solvent
was removed in Vacuo to yield 0.585 g (52%) of 7b as a clear oil.
1H NMR (C6D6, 25 °C): δ 7.67-7.64 (m, 6H, aromatics), 7.24-
7.16 (m, 9H, aromatics), 4.40 (pent, J ) 3.6 Hz, 1H, Ge-H), 1.47-
1.34 (m, 4H, aliphatics), 1.24 (sext, J ) 7.8 Hz, 4H, GeCH2-
CH2CH2CH3), 1.17-1.08 (m, 4H, aliphatics), 0.80 (t, J ) 7.5 Hz,
6H, GeCH2CH2CH2CH3) ppm. 13C NMR (C6D6, 25 °C): δ 139.3,
135.7, 128.7, 128.6 (aromatic carbons), 28.7, 26.7, 14.0, 13.7
(aliphatic carbons) ppm. IR (Nujol): 2036.2 cm-1 (νGe-H). Anal.
Calcd for C26H34Ge2: C, 63.50; H, 6.96. Found: C, 63.60; H, 7.10.
1
remove impurities to yield 9b as a clear oil (0.580 g, 33%). H
NMR (C6D6, 25 °C): δ 7.74-7.63 (m, 6H, aromatics), 7.23-7.12
(m, 9H, aromatics), 4.91 (pent, J ) 3.0 Hz, 1H, Ge-H), 1.61-1.09
(m, 24H, aliphatics), 0.80 (t, J ) 7.2 Hz, 12H, -CH2CH2CH2CH3)
ppm. 13C NMR (C6D6, 25 °C): δ 139.2, 135.7, 128.7, 128.5
(aromatic carbons), 30.6, 28.7, 26.7, 26.2, 14.0, 13.7, 10.3, 7.05
(aliphatic carbons) ppm. IR (Nujol): 2000.0 cm-1 (νGe-H). We were
not able to obtain a satisfactory elemental analysis for 9b.
Synthesis of Ph3GeGe(Et2)Ge(Et2)Ge(Et2)CH2CH2OEt (10a).
To a solution of 9a (0.056 g, 0.099 mmol) in acetonitrile (10 mL)
was added a solution of 5a (0.025 g, 0.104 mmol) in acetonitrile
(10 mL). The reaction mixture was sealed in a Schlenk tube
equipped with a Teflon plug, and the reaction mixture was heated
at 85 °C for 48 h. The solution was transferred to a Schlenk flask,
and the volatiles were removed in Vacuo. The crude product was
distilled in a Kugelrohr oven (oven temp ) 115 °C, P ) 0.07 Torr)
to remove excess 5a, yielding 10a (0.073 g, 97%) as a viscous
clear oil. 1H NMR (C6D6, 25 °C): δ 7.62-7.59 (m, 6H, aromatics),
7.25-7.12 (m, 9H, aromatics), 3.59 (t, J ) 7.5 Hz, 2H, GeCH2CH2-
OEt), 3.30 (q, J ) 6.8 Hz, 2H, -OCH2CH3), 1.36 (t, J ) 7.8 Hz,
3H -OCH2CH3), 1.18-0.89 (m, 32 H, aliphatics) ppm. 13C NMR
(C6D6, 25 °C): δ 139.2, 135.6, 128.7, 128.6, 67.5 (-OCH2CH3),
65.8 (GeCH2CH2O-), 19.1, 15.5, 14.0, 10.5, 10.2, 8.6, 8.3, 6.1
(aliphatic carbons) ppm. UV/visible: λmax 241 (ꢀ ) 1.8 × 104 L
mol-1 cm-1). Anal. Calcd for C34H54Ge4O: C, 53.09; H, 7.08.
Found: C, 53.29; H, 7.22.
Synthesis of Ph3GeGe(Et2)Ge(Et2)CH2CH2OEt (8a). To a
solution of 7a (0.322 g, 0.739 mmol) in acetonitrile (10 mL) was
added a solution of 5a (0.185 g, 0.746 mmol) in acetonitrile (5
mL). The reaction was sealed in a Schlenk tube and heated to 90
°C for 72 h. The volatiles were removed in Vacuo to yield 0.425 g
1
(90%) of 8a as a pale yellow liquid. H NMR (C6D6, 25 °C): δ
7.62-7.58 (m, 6H, aromatics), 7.22-7.14 (m, 9H, aromatics), 3.28
(t, J ) 6.6 Hz, 2H, GeCH2CH2OEt), 3.14 (q, J ) 6.9 Hz, 2H,
-OCH2CH3), 1.04-0.97 (m, 17H, Ge(CH2CH3)2 and -OCH2CH3),
(0.90, t, 6H, Ge(CH2CH3)2), 0.74 (t, 2H, J ) 6.6 Hz, GeCH2CH2-
OEt) ppm. 13C NMR (C6D6, 25 °C): δ 139.2, 135.6, 128.7, 128.5
(aromatic carbons), 67.2 (-OCH2CH3), 65.9 (GeCH2CH2O-), 15.3,
14.0, 10.2, 8.6, 6.1, 5.6 (aliphatic carbons) ppm. Anal. Calcd for
C30H44Ge3O: C, 56.43; H, 6.94. Found: C, 57.23; H, 6.86.
Synthesis of Ph3GeGe(Bu2)Ge(Bu2)Ge(Bu2)CH2CH2OEt (10b).
To a solution of 9b (0.370 g, 0.540 mmol) in acetonitrile (10 mL)
was added a solution of 5b (0.174 g, 0.570 mmol) in acetonitrile
(10 mL). The reaction mixture was sealed in a Schlenk tube
equipped with a Teflon plug, and the reaction mixture was heated
Synthesis of Ph3GeGe(Bu2)Ge(Bu2)CH2CH2OEt (8b). To a
solution of 7b (1.777 g, 3.62 mmol) in acetonitrile (20 mL) was
added a solution of 5b (1.208 g, 3.98 mmol) in acetonitrile (10

Preparation of Oligogermanes Via Hydrogermolysis
Organometallics, Vol. 25, No. 13, 2006 3219
Table 3. Crystallographic Data for Compounds 1 and 2
at 85 °C for 48 h. The solution was transferred to a Schlenk flask,
and the volatiles were removed in Vacuo. The crude product was
distilled in a Kugelrohr oven (oven temp ) 105 °C, P ) 0.03 Torr)
to remove excess 5b, yielding 10b (0.430 g, 85%) as a viscous
clear oil. 1H NMR (C6D6, 25 °C): δ 7.70-7.58 (m, 6H, aromatics),
7.23-7.08 (m, 9H, aromatics), 3.35 (t, J ) 7.2 Hz, 2H, GeCH2CH2-
OEt), 3.19 (q, J ) 6.0 Hz, 2H, -OCH2CH3), 1.52-1.02 (m, 29H,
aliphatics), 0.94-0.72 (m, 30H, aliphatics) ppm. 13C NMR (C6D6,
25 °C): δ 139.2, 135.6, 128.7, 128.5, 68.5 (-OCH2CH3), 65.8
(GeCH2CH2O-), 31.9, 28.7, 28.6, 26.7, 22.9, 16.2, 15.4, 15.0, 14.4,
14.2, 14.0, 13.7, 10.3, 7.0 (aliphatic carbons) ppm. UV/visible: λmax
235 (ꢀ ) 1.4 × 104 L mol-1 cm-1). Anal. Calcd for C46H78Ge4O:
C, 58.93; H, 8.38. Found: C, 58.85; H, 8.11.
Preparation of 10b Directly from 8b. To a solution of 8b (0.94
g, 1.14 mmol) in benzene (30 mL) in a Schlenk flask was added a
1 M solution of DIBAL-H in hexane (1.50 mL, 1.50 mmol). The
resulting solution was refluxed under N2 for 24 h and allowed to
cool, and the volatiles were removed in Vacuo, yielding a pale
yellow oil. The product was directly transferred to a Schlenk tube,
where a solution of 5b (0.380 g, 1.25 mmol) in acetonitrile (30
mL) was added. The tube was sealed with a Teflon plug and heated
at 95 °C for 48 h. The volatiles were removed in Vacuo, resulting
in an orange oil. The crude material was filtered through a 1 in. ×
1 in. silica gel column using 40 mL of benzene as the eluent to
yield 0.876 g (75%) of 10b as a pale yellow liquid after removal
of the solvent. The identity of 10b was confirmed by NMR (1H
and 13C) spectroscopy.
Synthesis of Bu3GeCH2CN. To a solution of HN(Pri)2 (0.70
mL, 5.0 mmol) in THF (20 mL) was added a 2.5 M solution of
BunLi in hexane (2.04 mL, 5.1 mmol) at -78 °C. The solution
was stirred for 30 min, and acetonitrile (0.27 mL, 5.2 mmol) was
added. The resulting suspension was placed in a -30 °C bath, and
a solution of Bu3GeCl (1.391 g, 4.97 mmol) in THF (15 mL) was
added at this temperature. The reaction mixture was allowed to
come to room temperature and was stirred for 12 h. The volatiles
were removed in Vacuo to yield a white solid, which was dissolved
in hexane (15 mL) and filtered through Celite. Removal of the
volatiles yielded Bu3GeCH2CN, 1.19 g (84%). 1H NMR (C6D6, 25
°C): δ 1.82-1.49 (m, 20H, Ge(CH2CH2CH2CH3)3 and GeCH2-
CN), 1.08 (t, J ) 7.2 Hz, 9H, Ge(CH2CH2CH2CH3)3 ppm. 13C NMR
(C6D6, 25 °C): δ 68.1 (-CH2CN), 28.4, 27.5, 25.7 (butyl group
carbons), 16.0 (GeCH2CN), 14.3 (-CH2CH2CH2CH3) ppm.
Synthesis of 1 Using Bu3GeCH2CN. A Schlenk tube was
charged with Bu3GeCH2CN (0.253 g, 0.890 mmol) in acetonitrile
(10 mL). To this was added a solution of Ph3GeH (0.270 g, 0.885
1
2
formula
space group
a (Å)
b (Å)
c (Å)
C30H42Ge2
P1h
C24H27Ge2
R3h
15.533(1)
15.533(1)
16.275(3)
90
90
120
3400.4(7)
6, 1
1.350
213(2)
Mo KR
0.71073
0.0333
0.0932
10.051(3)
15.141(4)
20.970(6)
109.043(4)
100.239(4)
98.645(4)
2893.1(1)
4, 2
R (deg)
Β (deg)
γ (deg)
V (Å3)
Z, Z′
F
calc (g cm-3
temperature (K)
)
1.258
215(2)
Mo KR
0.71073
0.0485
radiation
wavelength (Å)
R
Rw
0.1199
mmol) in acetonitrile (10 mL). The tube was sealed with a Teflon
plug and was heated at 90 °C for 50 min, and the solution was
transferred to a Schlenk flask. The volatiles were removed in Vacuo,
yielding 0.434 g (89%) of 1. The identity of 1 was confirmed by
NMR (1H and 13C) spectroscopy.
X-ray Structure Determination. Diffraction intensity data were
collected with a Siemens P4/CCD diffractometer. Crystallographic
data and details of X-ray studies are shown in Table 3. The
asymmetric unit of 1 contains two crystallographically independent
but chemically equivalent molecules. Absorption corrections were
applied for all data by SADABS. The structures were solved using
direct methods, completed by difference Fourier syntheses, and
refined by full matrix least squares procedures on F2. All non-
hydrogen atoms were refined with anisotropic displacement coef-
ficients, and hydrogen atoms were treated as idealized contributions.
All software and sources of scattering factors are contained in the
SHEXTL (5.10) program package (G. Sheldrick, Bruker XRD,
Madison, WI). ORTEP diagrams were drawn using the ORTEP3
program (L. J. Farrugia, Glasgow).
Acknowledgment. We are grateful for funding for this work
which was provided by Oklahoma State University.
Supporting Information Available: Crystallographic data for
1 and 2 in cif format. This information is available free of charge
via the Internet at http://pubs.acs.org.
OM060115X