Development of novel and efficient synthesis of group 14 element (Ge and Sn) catenates by use of samarium (II) diiodide

Article abstract of DOI:10.1016/j.jorganchem.2004.12.032

Group 14 element catenates such as di-, tri-, poly-germanes, and polystannanes are efficiently synthesized by use of the one-electron reducing agent SmI₂ under mild homogeneous conditions in good yields.

Full text of DOI:10.1016/j.jorganchem.2004.12.032

Journal of Organometallic Chemistry 690 (2005) 1588–1593
www.elsevier.com/locate/jorganchem
Development of novel and efficient synthesis of group 14 element
(Ge and Sn) catenates by use of samarium (II) diiodide
1
Takushi Azemi, Yasuo Yokoyama , Kunio Mochida
*
Department of Chemistry, Faculty of Science, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo 171-8588, Japan
Received 17 June 2004; accepted 21 December 2004
Abstract
Group 14 element catenates such as di-, tri-, poly-germanes, and polystannanes are efficiently synthesized by use of the one-
electron reducing agent SmI2 under mild homogeneous conditions in good yields.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Group 14 elements; Catenates; Samarium (II) diiodide
1. Introduction
milder, safer and more efficient methods are desirable.
In this paper, we describe a new synthetic procedure
for the formation of Group 14 element (Ge and Sn) cat-
enates by use of samarium (II) diiodide (SmI2). This
reaction is particularly useful for the synthesis of poly-
germanes and polystannanes which are difficult to ob-
tain in high yields by the Kipping method. SmI2 is
known to be a mild one-electron reducing agent and
homogeneous nature, and it has been applied in a wide
variety of carbon–carbon bond formation reactions [10].
Group 14 element (silicon, germanium, tin) backbone
polymers have attracted considerable attention as a new
class of soluble, film-forming polymers due to both their
promising physical, chemical and optical properties and
their potential technological utility [1–9]. Much atten-
tion is, therefore, being directed towards the develop-
ment of synthetic routes. The most practical synthetic
procedure for Group 14 element catenates is a Wurtz-
type polycondensation of Group 14 element dihalides
with an alkali metal (Kipping method). These reactions
are usually carried out under vigorous conditions and
often lead to low yields of the polymers because of their
heterogeneous nature. Moreover, such reactions, in
which moisture-sensitive alkali metals are used at ele-
vated temperature, can be hazardous. Therefore, much
2. Results and discussion
The formation of a germanium–germanium bond is
first attempted by use of SmI2. Digermanes are generally
synthesized by treatment of halogermanes with an alkali
metal [11]. However, the germanium–germanium bond
formed by reductive coupling is easily cleaved under
reductive conditions. Organodigermanes were cleaved
with alkali metal to give the corresponding germyl anion
species [12]. Therefore, it is significant that a mild reduc-
ing agent is chosen as a promoter of reductive formation
of a germanium–germanium bond for control over
*
Corresponding author. Tel.: +81 3 3986 0221; fax: +81 3 5992
1029.
E-mail address: kunio.mochida@gakushuin.ac.jp (K. Mochida).
Present address: Department of Chemistry, Faculty of Science
1
and Technology, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo
102-8554, Japan.
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.12.032

T. Azemi et al. / Journal of Organometallic Chemistry 690 (2005) 1588–1593
1589
cleavage of the formed bond. If the reductive potential
of the reductant is too weak, the reductive coupling
reaction of halogermanes can not proceed. SmI2 has
mild reduction potential (Sm2+ = Sm3+ + eꢀ; ꢀ1.55 V,
M = M+ + eꢀ; ꢀ2.9 ꢁ ꢀ3.0 V, M = alkali metals) and
its reaction is carried out in a homogeneous system
[10]. These facts prompted us to investigate the forma-
tion of a germanium–germanium bond by reductive
coupling of halogermanes.
The reactions of various halogermanes used as sub-
strates and coupling reactions of them with 2 equiv. of
SmI2 in THF–HMPA mixed solvents at room tempera-
ture were carried out. After stirring, this reaction mix-
ture was passed through a short column of silica gel
and eluted with ether. This ether eluate was evaporated
and purified by silica gel (hexane only) to give digerm-
anes as major products. Products were identified by
comparing their IR, NMR, GC–MS spectra, and reten-
tion times on GC with those of authentic samples. The
results are summarized in Table 1.
and hexa-i-propyl-digermanes could be obtained in
good yields, when the corresponding chlorogermanes
or bromogermanes were treated with SmI2 (Entries
3–6). In all cases, the reductive coupling of bromo-
germanes by use of SmI2 gave efficiently the corre-
sponding digermanes compared with those of
chlorogermanes. Phenyl-substituted digermanes also
could be given by this method under similar reductive
conditions. Diphenylmethylhalogermanes were used as
substrates to give the corresponding tetraphenyl-substi-
tuted digermanes in excellent yields (Entries 7 and 8).
In contrast to alkyl-substituted halogermanes, phenyl-
substituted halogermanes were easily reduced to afford
the corresponding digermanes (Entries 1 vs. 7 and 2 vs.
8). These results led to synthesize asymmetric digerm-
anes by the combination of chlorogermane and brom-
ogermane. Anticipated reductive coupling of the
corresponding halogermanes occurred and 1,1,1-tri-
ethyl-2,2,2-triphenyldigermane or 1,1,1-tributyl-2,2,2-
trimethyldigermane were obtained in good to excellent
yields (Entries 9 and 10). These types of compounds
could not be produced in good yields by treatment
of halogermanes with an alkali metal.
As shown in Table 1 SmI2 is a useful reagent for the
formation of germanium–germanium bonds from halog-
ermanes. This result suggested that other Group 14 ele-
ment catenates could be synthesized by SmI2. Therefore,
we tried to investigate applications of this method for
various catenate compounds.
Organotrigermanes are mostly prepared by two
methods: (1) the reaction of dihalogermanes and two
equiv of halogermanes with alkali metals, and (2) by
treatment of halogermanes and monohalodigermanes
with alkali metals [11]. These procedures are multiple-
step reactions and the corresponding trigermanes were
produced in low yields. It is obviously unfavorable as
a practical procedure for organotrigermanes. As men-
tioned above, SmI2 was useful for the synthesis of
Group 14 element catenates. Therefore, synthesis of var-
ious trigermanes and analogues using SmI2 was
examined.
2 SmI2
2R GeX
3
R GeGeR R ¼ alkyl; aryl
ƒƒƒƒƒƒƒƒ!
3
3
THF; HMPA; r:t:
Chlorotriethylgermane (Et3GeCl) was treated with
2 equiv. of SmI2 in THF/hexamethylphosphoric tria-
mide (HMPA) at room temperature for 24 h to give
hexaethyldigermane (Et3GeGeEt3) in 69% isolated
yield (Entry 1). This reaction progressed without
HMPA, but the reaction mixtures should be stirred
for long reaction periods (>100 h) to give Et3GeGeEt3
in good yield. Therefore, HMPA was necessary for this
reductive coupling of Et3GeCl at the point of practical
protocols. When more reactive bromotriethylgermane
(Et3GeBr) was used as a substrate, the reaction mix-
ture was stirred at room temperature for 15 h to afford
Et3GeGeEt3 in good yield (73%) (Entry 2). Sterically
hindered digermanes could be synthesized by reductive
coupling of halogermanes by use of SmI2. Hexabutyl-
Table 1
The formation of Ge–Ge Bond by use of SmI2
a
Reaction conditions for the formation of trigerm-
anes were optimized using Et3GeCl and dibromophe-
nylgermane (Ph2GeBr2) as model substrates. 1,1,1,3,3,
Entry
Substrates
Time (h)
Yieldb (%)
1
2
Et3GeCl
Et3GeBr
24
15
24
15
24
15
12
1
69
73
62
66
39
45
95
98
96
59
3-hexaethyl-2,2-diphenyltrigermane
((Et3Ge)2GePh2)
3
n-Bu3GeCl
n-Bu3GeBr
was identified by the IR, NMR, and GC–MS spectra,
and retention times on GC with those of authentic
samples.
4
5
i-Pr3GeCl
i-Pr3GeBr
6
7
Ph2MeGeCl
Ph2MeGeBr
Et3GeCl + Ph3GeBr
n-Bu3GeCl + Me3GeBr
Ph
8
excess SmI2
9c
10d
a
1
15
2 Et3GeCl + Ph2GeBr2
Et3Ge Ge GeEt3
THF, HMPA, r.t.
Ph
THF solution of SmI2 (0.1 mol/dm3) and HMPA (8% V/V) were
used.
b
As shown in Table 2, THF solution of SmI2 was
added to the mixture of Et3GeCl and Ph2GeBr2 in
HMPA to give trigermane (Et3Ge)2GePh2 in 63%
Isolated yield.
Et3GeCl/Ph3GeBr = 1/1.
n-Bu3GeBr/Me3GeBr = 1/1.
c
d

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T. Azemi et al. / Journal of Organometallic Chemistry 690 (2005) 1588–1593
Table 2
Synthesis of (Et3Ge)2GePh2 by use of SmI2
a
Method
Additional reagent
Mother liquor
Yieldb (%)
A
B
C
D
a
SmI2 in THF
Et3GeCl
Ph2GeBr2
Et3GeCl/Ph2GeBr2 in HMPA
Ph2GeBr2/SmI2 in THF/HMPA
Et3GeCl/SmI2 in THF/HMPA
SmI2 in THF/HMPA
63
0
38
77
Et3GeCl/Ph2GeBr2 in THF
THF solution of SmI2 (0.1 mol/dm3) and HMPA (8% V/V) were used.
Isolated yield.
b
Ph
isolated yield (method A). In contrast, a mixture of this
reducing reagent and Ph2GeBr2 in THF/HMPA was
added to Et3GeCl. Many by-products were formed
and the desired (Et3Ge)2GePh2 could not obtained
(method B). Furthermore, Ph2GeBr2 was added to the
solution of Et3GeCl and SmI2. The trigermane was
formed in low yield (method C). When the THF solu-
tion of Et3GeCl and Ph2GeBr2 was slowly added to
the THF/HMPA solution of SmI2, the corresponding
trigermane was given in the highest yield (method D).
Optimized reaction conditions of the formation of tri-
germanes were further examined by use of method D.
An increasing in the concentration of SmI2 relative to
Et3GeCl (from 5.0 to 10 equiv.) improved the yield of
(Et3Ge)2GePh2 (86%). Extending the dropping time
from 30 min to 2 h at room temperature improved the
yield of (Et3Ge)2GePh2 (86–94%). Lowering the reaction
temperature from room temperature to 0 ꢁC resulted in
lower yields of (Et3Ge)2GePh2 (94–74%), while raising
the temperature to 100 ꢁC showed a slight decrease,
affording (Et3Ge)2GePh2 in 85% yield. A decreasing in
the concentration of THF solution of Et3GeCl and 2
equiv. of Ph2GeBr2 afforded (Et3Ge)2GePh2 quantita-
tively. If concentrated solutions of substrates were
added to SmI2, (Et3Ge)2GePh2 was produced together
with a tetragermane, Et3Ge(Ph2Ge)2GeEt3, as a by-
product.
10 equiv. SmI2
THF, HMPA, rt
+
2 R3ECl
Ph2GeBr2
R3E Ge ER3
Ph
E = Ge or Sn; R = alkyl
Trigermanes having sterically hindered substituents
such as i-propyl group could be synthesized by this
method (Entry 2). Furthermore, Sn–Ge–Sn bond was
formed by the use of SmI2 (Entry 4). These types of
compounds are important because they can be used as
precursors for the formation of Sn–Ge bond containing
polymers, and a few synthetic methods have been re-
ported [13]. Therefore, SmI2-promoted reactions are sig-
nificant for efficient synthesis of these compounds in the
field of polymers containing Group 14 elements.
In the synthesis of trigermanes, the reaction of Et3-
GeCl, Ph2GeBr2, and SmI2 gave tetragermane, Et3-
by-product. This result
prompted us to apply SmI2 to the formation of polymers
containing Ge–Ge and Sn–Sn backbone bonds.
Ge(Ph2Ge)2GeEt3, as
a
R
2 SmI2
E
R
R2ECl2
THF, HMPA
n
R = Me, Et; E = Ge
R = Me, Et, Bu, Hex; E = Sn
At the next stage, applications of this reaction for the
preparation of various trigermanes and analogues by the
reaction of trialkyl-substituted Group 14 element chlo-
rides (R3ECl, E = Ge, Sn; R = alkyl) with Ph2GeBr2
were investigated. All products were identified by their
IR, NMR, and GC–MS spectra. These results are sum-
marized in Table 3.
Polymerization of R2ECl2 (R = alkyl; E = Ge, Sn) by
use of SmI2 under various conditions was examined. Re-
sults of polymerization of R2ECl2 by use of 2 equiv. of
SmI2 are summarized in Table 4. First, we investigated
polymerization of Bu2GeCl2 by treatment of SmI2 in
THF/HMPA at room temperature for 24 h. The
Table 3
Synthesis of trigermanes and analogues by use of SmI2
a
Entry
R3Ecl
Ph2GeBr2
Product
Yieldb (%)
1
2
3
a
Me3GeCl
i-Pr3GeCl
Et3SnCl
Ph2GeBr2
Ph2GeBr2
Ph2GeBr2
(Me3Ge)2GePh2
(i-Pr3Ge)2GePh2
(Et3Sn)2GePh2
87
30
39
THF solution of SmI2 (0.1 mol/dm3) and HMPA (8%V/V) were used.
Isolated yield.
b

T. Azemi et al. / Journal of Organometallic Chemistry 690 (2005) 1588–1593
1591
Table 4
Polymerization of R2ECl2 by use of SmI2
a
Yieldb (%)
a
a
Entry
E
R
Temperature (ꢁC)
Time (h)
kmax (nm)
Mw
Mn
Mw/Mn
1
2
3
4
5
6
7
8
a
Ge
Ge
Ge
Sn
Sn
Sn
Sn
Sn
Me
Et
reflux
rt
1
24
1
327
289
325
285
368
367
289
305
4200
2380
4890
1120
4820
4100
2100
2770
3700
2030
4330
750
1.14
1.17
1.13
1.49
1.21
1.15
1.04
1.18
9
19
25
19
74
76
17
6
Et
reflux
rt
Me
Et
24
24
5
rt
3980
3570
2030
2340
Et
reflux
rt
Bu
Hex
65
65
rt
Determined by GPC based on polystyrene standard.
Isolated yield.
b
poly(diethylgermane)s, (Et2Ge)n, produced using SmI2
had a narrow molecular weight distribution, but rela-
tively low in molecular weight (Mw = 2380, Mw/
Mn = 1.17, Entry 2). Raising the reaction temperature
from 23 to 65 ꢁC resulted in higher molecular weight
ticularly, syntheses of asymmetric digermane, triger-
mane analogues having Sn–Ge–Sn bonds, and
polystannanes are very important in the field of Group
14 elements because they have so far been difficult to
be formed by practical methods. We believe that this
convenient method would be generally applicable to a
wide range of Group 14 element catenates and related
compounds.
of (Et2Ge)n with
a narrow Mw/Mn and higher
(Mw = 4890, Mw/Mn = 1.13, Entry 3). The yields of (Et2-
Ge)n were also increased (19–25%). The (Et2Ge)n pre-
pared by Wurtz-type coupling of dichlorogermanes
with sodium metal in dispersion at elevated temperature
showed a distinctly bimodal broad Mw/Mn and molecu-
lar weight in excess of about (3–4) · 105 were obtained
[7.8.9f]. Therefore, polymerization of dichlorogermanes
using SmI2 is much milder, safer, and more efficient
methods.
Polymerization of Et2SnCl2 by treatment of SmI2 in
THF/HMPA at room temperature for 24 h and reflux
temperature for 1 h was examined (Entries 5, 6). The
poly(diethylstannane)s, (Et2Sn)n, showed a narrow
molecular weight distribution (Mw/Mn = 1.15–1.21)
and molecular weights in (4.1–4.9) · 103 were obtained.
Raising the reaction temperature from 23 to 65 ꢁC scar-
cely improved the molecular weight of (Et2Sn)n. Poly-
merization of other dichlorostannanes by using SmI2
in THF/HMPA at room temperature were also exam-
ined (Entries 4, 7, 8). Polystannanes were difficult to syn-
thesize in good yields by the Kipping method [13]. The
tin-tin bond formed by reductive coupling is easily
cleaved under reductive conditions due to its weak bond
strength. This method by using SmI2 can be applied for
the formation of various polystannanes under mild
conditions.
4. Experimental
1H- and 13C NMR spectra were recorded in CDCl3
with tetramethysilane (TMS) as an internal standard
on Varian Unity Inova-400. GC–MS were measured
with JEOL JMS-DX 303 mass spectrometer. The UV
and UV–Vis spectra were recorded with a Shimadzu
UV 2200 spectrometer. IR spectra were recorded on Shi-
madzu FT IR 4200 spectrometer. GPC was performed
with JAI LC-908 and Jasco UVDEC-100-IV. Gas chro-
matographic analyses were performed with Shimadzu
GC-8A equipped with 1 m 20% SE30. Column chroma-
tography was performed with silica gel (Wako Pure
Chemical Industries, Ltd., Wakogel C-300). Thin-layer
chromatography was performed on 0.25 mm E. Merck
silica gel plates (60F-254).
4.1. Materials
Sodium metal, lithium metal, magnesium and samar-
ium metal were commercially available products. Dieth-
ylether and THF were distilled from sodium
benzophenone ketyl under nitrogen before use. Dibuty-
lether was dried over sodium wire and distilled before
use. HMPA was dried over calcium hydride and purified
by distillation under argon atmosphere. MeOH and tol-
uene were purified by distillation prior to use. All sol-
vents of column chromatography and the other
commercial reagents were used without purification.
Compounds Et3GeCl [14], Et3GeBr [14], i-Pr3GeCl
[15], i-Pr3GeBr [15], n-Bu3GeCl [16], n-Bu3GeBr [16],
Ph2MeGeCl [17], Ph2MeGeBr [17], Ph3GeBr [18],
3. Conclusion
In this paper, we have described the synthesis of use-
ful various Group 14 element catenates, such as digerm-
anes, trigermanes (and analogues), polygermanes, and
polystannanes by treatment of Group 14 element halides
with SmI2 which is well-known as a mild one-electron
reducing reagent under homogeneous conditions. Par-

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T. Azemi et al. / Journal of Organometallic Chemistry 690 (2005) 1588–1593
Me3GeBr [19], Ph2GeBr2 [20], (Et3Ge)2 [21], (n-Bu3Ge)2
[21], (i-Pr3Ge)2 [22], (Ph2MeGe)2 [23], Me3GeGeBu3
[21], Et3GeGePh3 [24], Me2GeCl2 [25], Et2GeCl2 [26],
Me2SnCl2 [27], Et2SnCl2 [28], Bu2SnCl2 [29], Hex2SnCl2
[30], (Me3Ge)2GePh2 [31], (Et3Sn)2GePh2 [32], (Et2Ge)n
[9f], and (Et2Sn)n [13] were prepared in accordance
with reported procedures. THF solution of SmI2
(0.1 mol/dm3) was prepared according to the literature
[33]. All reactions were carried out under argon or nitro-
gen atmosphere.
6H, J = 7.50 Hz), 1.09 (d, 36H, J = 7.50 Hz); 13C
NMR (d, CDCl3) 141.7, 136.3, 136.3, 127.5, 21.1, 17.7.
MS m/z (relative intensity): 630 (M+, 30), 587 (90), 545
(60), 427 (70), 385 (75), 352 (100), 301 (20), 203 (50),
161 (30). Found: C, 57.42; H, 8.52%. Calcd for
C30H52Ge3: C, 57.16; H, 8.32%.
4.4. Polymerization of R2ECl2 by use of SmI2
As a representative example, the preparation of
poly(diethylgermane) (Et2Ge)n was described. A THF
solution of SmI2 (16.0 mL, 1.60 mmol) was dropped to
HMPA solution of Et2GeCl2 (161 mg, 0.80 mmol). This
mixture was stirred for 1 h at reflux temperature. After
removing the solvent in vacuo, (Et2Ge)n was given by
recrystallization from MeOH (26.2 mg, 25%). (Et2Ge)n:
1H NMR (d, CDCl3) 1.17 (br, m); IR (cmꢀ1, neat)
2900, 2850, 1450, 1420, 1370, 1220, 1200, 1010, 940,
790, 670. (Me2Ge)n: 1H NMR (d, CDCl3) 0.20–0.47
(m); IR (cmꢀ1, neat) 2900, 2870, 1400, 1220, 820, 745.
(Me2Sn)n: 1H NMR (d, CDCl3) 1.15–1.36 (m); IR
4.2. Preparation of organodigermanes
As a representative example, the preparation of hexa-
ethyldigermane ((Et3Ge)2) is described. A THF solution
of SmI2 (3.0 mL, 0.30 mmol) was added to an HMPA
(0.24 mL) solution of Et3GeBr (36.0 mg, 0.15 mmol).
After stirring for 15 h at room temperature, this reaction
mixture was passed through a short column of silica gel
and eluted with ether. This ether eluate was evaporated
and purified by silica gel (hexane only) to give com-
pound Et3GeGeEt3 (17.5 mg, 73%). This digermane
was identified by comparison with an authentic com-
1
(cmꢀ1, KBr) 2860, 1470, 1380, 990, 720. (Et2Sn)n: H
NMR (d, CDCl3) 1.25–1.66 (m); IR (cmꢀ1, KBr) 2960,
1450, 1430, 1190, 940, 670, 570. (Bu2Sn)n: 1H NMR
(d, CDCl3) 1.49–1.87 (m); IR (cmꢀ1, KBr) 2980, 1635,
1465, 1070, 860, 670, 565. (Hex2Sn)n: 1H NMR (d,
CDCl3) 0.62–1.88 (m); IR (cmꢀ1, KBr) 960, 2400,
1640, 1155, 1100, 950, 680, 600.
1
pound (GC–MS and H NMR) which was described
in the literature [22].
4.3. Preparation of trigermanes and analogues
As a representative example, the preparation of
1,1,1,3,3,3-hexaethyl-2,2-diphenyltrigermane ((Et3Ge)2-
GePh2) is described. A THF solution (40 mL) of Et3-
GeCl (25.7 mg, 0.13 mmol) and Ph2GeBr2 (23.3 mg,
0.06 mmol) was added dropwise to a THF–HMPA
(12:1) solution of SmI2 (6.0 mL, 0.60 mmol) for 2 h at
room temperature. After being stirred for 1 h, the reac-
tion mixture was passed through a short column of silica
gel and eluted with ether. The evaporated ether eluate
was purified by silica gel (hexane only) to give com-
pound (Et3Ge)2GePh2 (30.8 mg, 94%). Tetragermane,
Et3Ge(Ph2Ge)2GeEt3, was also detected. 1,1,1,3,3,3-
Hexaethyl-2,2-diphenyltrigermane: IR (neat, NaCl)
3067, 3052, 3021, 3009, 2950, 2928, 2905, 2870, 2826,
1562, 1482, 1429, 1378, 1080, 1011, 968, 731, 698, 565
Acknowledgements
The author (T.A.) thanks Professor Koichi Narasaka
of Tokyo University for valuable discussion of reaction
mechanism of SmI2 and Group 14 element dihalides.
References
[1] R. West, in: G. Wilkinson, F.G.A. Stone, E.W. Abel (Eds.),
Comprehensive Organometallic Chemistry, vol. 2, Pergamon,
Oxford, 1982 (Chapter 9.4).
[2] H. Sakurai, Synthesis and Application of Organopolysilanes,
CMC, Tokyo, 1989.
1
cmꢀ1; H NMR (d, CDCl3) 7.46–7.26 (m, 10H), 0.98
[3] R. West, J. Organomet. Chem. 300 (1986) 327, and references
cited therein.
(m, 30H); 13C NMR (d, CDCl3) 140.2, 135.5, 127.8,
127.3, 9.9, 6.1. MS m/z (relative intensity): 546 (M+,
30), 517 (25), 461 (20), 431 (20), 381 (80), 310 (100),
280 (40), 151 (50), 103 (25). 1,1,1,4,4,4-Hexaethyl-
[4] M. Ishikawa, M. Kumada, Adv. Organomet. Chem. 51 (1981) 19,
and references cited therein.
[5] H. Sakurai, Yuki Gosei Kagaku Kyoukaishi 47 (1989) 1051, and
references cited therein.
1
2,2,3,3-tetraphenyltetragermane: H NMR (d, CDCl3)
[6] R.D. Miller, J. Michl, Chem. Rev. 89 (1989) 1359.
[7] P. Treonas, R. West, J. Polym. Sci. 23 (1985) 1359.
[8] R.D. Miller, R. Sooriyakumaran, J. Polym. Sci. Polym. Chem.
Ed. 25 (1987) 111.
7.42–7.21 (m, 20H), 0.79 (s, 30H). MS m/z (relative
intensity): 774 (M+, 10), 536 (100), 359 (20), 301 (10),
257 (5), 209 (3), 151 (3). 2,2-Diphenyl-1,1,1,3,3,3-hexa-
i-propyltrigermane: a white solid; 156–177 ꢁC (de-
comp.); IR (KBr) 3096, 2967, 2942, 2917, 2882, 2962,
[9] (a) M. Okano, K. Mochida, Chem. Lett. (1990) 701;
(b) K. Mochida, H. Chiba, M. Okano, Chem. Lett. (1991) 109;
(c) K. Mochida, S. Masuda, Y. Harada, Chem. Lett. (1992) 2281;
(d) K. Mochida, C. Hodota, R. Hata, S. Fukuzumi, Organomet-
allics 12 (1993) 586;
1462, 1431, 1221, 1078, 1001, 876, 729, 700, 523 cmꢀ1
1H NMR (d, CDCl3) 7.64–7.25 (m, 10H), 1.65 (sept,
;

T. Azemi et al. / Journal of Organometallic Chemistry 690 (2005) 1588–1593
1593
(e) K. Mochida, K. Kimijima, H. Chiba, M. Wakasa, H. Hayashi,
Organometallics 13 (1994) 404;
[16] H.H. Anderson, J. Am. Chem. Soc. 73 (1951) 5800.
[17] M. Kumada, S. Sakamoto, M. Ishikawa, J. Organomet. Chem. 17
(1974) 1309.
(f) K. Mochida, H. Chiba, J. Organomet. Chem. 473 (1994) 45;
(g) K. Mochida, M. Shimoda, H. Kurousu, A. Kojima, Polyhe-
dron 13 (1994) 3039;
[18] E.H. Brooks, F. Glockling, J. Chem. Soc. A (1966) 1241.
[19] E.N. Abel, D.A. Armitage, D.B. Brady, J. Org. Chem. 5 (1966)
130.
(h) Y. Yokoyama, M. Hayakawa, T. Azemi, K. Mochida, J.
Chem. Soc., Chem. Commun. (1995) 2275;
[20] O.H. Johnson, D.M. Harris, J. Am. Chem. Soc. 72 (1950)
5564.
(i) K. Mochida, T. Ohkawa, H. Kawata, A. Watanabe, O. Ito,
M. Matsuda, Bull. Chem. Soc. Jpn. 69 (1996) 2993;
(j) K. Mochida, S. Nagano, S. Maeyama, T. Kodaira, A. Watanabe,
O. Ito, M. Matsuda, Bull. Chem. Soc. Jpn. 70 (1997) 713;
(k) K. Mochida, S. Nagano, H. Kawata, M. Wakasa, H. Hayashi,
J. Organomet. Chem. 542 (1997) 75;
[21] E.J. Bulten, J.G. Noltes, Tetrahedron Lett. 36 (1966) 4389.
[22] F.G. Glockling, A. Carrik, J. Chem. Soc. (1963) 1849.
[23] H. Bauer, K. Burcshkies, Chem. Ber. (1934) 2617.
[24] C.A. Kraus, S. Sherman, J. Am. Chem. Soc. 55 (1933) 4694.
[25] A.E. Finholt, Nucl. Sci. Abstr. 6 (1957) 617.
[26] L. Horviz, E.A. Flood, J. Am. Chem. Soc. 55 (1933) 5055.
[27] K. Gingold, E.G. Rochow, D. Seyferth, A. Smith, R.C. West, J.
Am. Chem. Soc. 74 (1952) 6306.
(l) K. Mochida, S. Nagano, H. Kawata, M. Wakasa, H. Hayashi,
J. Appl. Organomet. Chem. 11 (1997) 949.
[10] G.A. Molander, Chem. Rev. 92 (1992) 29, and references cited
therein.
[28] U. Schroer, H.-J. Albert, W.P. Neumann, J. Organomet. Chem.
102 (1975) 291.
[11] C. Tamborski, F.E. Ford, W.L. Lehn, G.L. Moore, E.J. Soloski,
J. Org. Chem. 27 (1962) 619.
[29] O.H. Johnson, H.E. Fritz, J. Org. Chem. 25 (1960) 2262.
[30] E. Krause, R. Pohland, Chem. Ber. 57 (1924) 532.
[31] J. Satge, P. Riviere, A. Boy, C.R. Acad. Sci. Ser. C 278 (1974)
1309.
[12] (a) D.D. Davis, C.E. Gray, Organomet. Chem. Rev. A 6 (1970)
283;
(b) E.J. Bulten, J.G. Noltes, Tetrahedron Lett. (1966) 4389.
[13] W.K. Zou, N.-L. Yang, Poly. Prepr., Am. Chem. Soc. 33 (1992)
188, and references cited therein.
[32] H.M.J.C. Creemers, J.G. Noltes, J. Organomet. Chem. 7 (1967)
237.
[14] H.H. Anderson, J. Am. Chem. Soc. 79 (1957) 326.
[15] H.H. Anderson, J. Am. Chem. Soc. 75 (1957) 814.
[33] P. Griard, J.L. Namy, H.B. Kagan, J. Am. Chem. Soc. 102 (1980)
2693.