Exchange reactions in alkoxy derivatives of silicon and germanium

Article abstract of DOI:10.1023/B:RUJO.0000043709.78426.02

Reaction SiCl₄+ Ge(OR)₄ → GeCl₄+ Si(OR)₄ was carried out for the first time. Triethoxysilane reduces tetraethoxygermane via intermediate formation of unstable GeH(OEt)₃ that transforms into GeO·Et₂O or Ge(OH)₂.

Full text of DOI:10.1023/B:RUJO.0000043709.78426.02

Russian Journal of Organic Chemistry, Vol. 40, No. 5, 2004, pp. 650-652. Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 5, 2004,
pp. 681-683.
Original Russian Text Copyright Ó 2004 by Chernyshev, Belyakova, Knyazev, Turkel’taub, Ovsyankina, Ugarova, Yakovleva.
.
Exchange Reactions in Alkoxy Derivatives of Silicon
and Germanium
E.A. Chernyshev1, Z.V. Belyakova1, S.P. Knyazev2, G.N. Turkel’taub2,
E.A. Ovsyankina2, I.N. Ugarova2, and N.V. Yakovleva2
1State Scientific Center of Russian Federation, State Research Institute of Chemistry and Processing
of Organoelemental Compounds, Moscow, 111123 Russia
2Moscow Institute of Fine Chemical, Moscow, Russia
Received December 20, 2003
Abstract—Reaction SiCl4 + Ge(OR)4 ’GeCl4 + Si(OR)4 was carried out for the first time. Triethoxysilane reduces
tetraethoxygermane via intermediate formation of unstable GeH(OEt)3 that transforms into GeO·Et2O or Ge(OH)2.
reactions under study obtained as difference between
the respective parameters of products and reagents are
compiled in Tables 1 and 2.
Exchange of alkyl substituents between silicon and
germanium is known [1], and also a reduction of
alkyltrichlorogermane with methyldichlorosilane has been
reported [2,3]. In attempt to reduce selectively germanium
tetrahalides Me2SiHCl, HSiCl3, (EtO)3SiH were tried, but
these compounds failed to react with GeCl4 in ether [4].
The results obtained evidence the possibility of
reactions going in the direction of products for the
difference between free energy of products and reagents
has a negative value.
This study was aimed at elucidation of the possibility
of exchange by substituents H, OR between silicon and
germanium compounds in the following systems:
We actually found experimentally that reaction (1)
occurred at room temperature without catalyst for R =
Et, Pr. The reaction went to completion practically in 2
h. The reaction mixture contained GeCl4 (44–48%) and
Si(OR)4 (48–53%).
Ge(OR) + SiCl gGeCl(OR) + GeCl (OR) + GeCl (OR)
4f
4
3
2
2
3
+ GeCl4 + SiCl3(OR) + SiCl2(OR)2 + SiCl(OR)3 + Si(OR)4
R = Et, Pr, Bu.
(1)
(2)
At R = Bu in 2 h the content of GeCl4 was 30%,
Si(OBu)4 34%. In 3 h the reaction mixture contained
GeCl4 (40%) and Si(OBu)4 (58%).
Ge(OEt) + SiH(OEt) gGeH(OEt) + Si(OEt)
4
The systems composed exclusively of germanium or
silicon compounds react in the presence of alcohol in
catalytical amounts similarly to alkyltrichlorosilane and
tetraethoxysilane described before [5].
3 f
4
3
The thermodynamic parameters of the reagents and
products of these reactions were subjected to quantum-
chemical calculations using software package Gaussian
98 in the ab initio approximation with the 6-31G(d,p)
basis accounting for the correlation corrections by DFT
procedure in B3LYPapproximation.As initial parameters
for calculation of the thermodynamic functions H, S,
and G were chosen temperatures 298.15, 473, 573, and
673 K at a pressure of 1 at. The analysis of frequencies
carried out on completing the calculations showed that
imaginary vibrations with the negative frequency values
were lacking for the molecules of all reagents and
products. This fact evidences the calculation of stationary
points corresponding to the minimum of potential energy
for the molecules in question. The calculation results for
the total energy, enthalpy, entropy, and free energy of
SiCl4 + Si(OR)4gSiCl3(OR) + SiCl2(OR)2 + SiCl(OR)3 (3)
f
GeCl4 + Ge(OR)4 gGeCl3(OR)+ GeCl2(OR)2 + GeCl(OR)3
f
(4)
The hydrogen transitionfrom triethoxysilane to
tetraethoxygermane (reaction 2, reduction of tetraethoxy-
germane with triethoxysilane) is also thermodynamically
allowed according to the calculations. The changes in
the reaction mixture were observed experimentally
already at room temperature. In 2 h in the reaction mixture
were found alongside the initial compounds also ethanol,
1070-4280/04/4005-0650Ó2004 MAIK “Nauka/Interperiodica”

EXCHANGE REACTIONS IN ALKOXY DERIVATIVES OF SILICON AND GERMANIUM
651
Table 1. Calculation results (Gaussian 98, B3LYP/6-31G**) of
thermodynamic parameters for reaction Ge(OEt)4 + SiCl4 =
GeCl4 + Si(OEt)4
tetraethoxysilane, and a substance that was eluted a little
later than tetraethoxysilane (poorly resolved peak). At
standing for several days (from 2 to 14) an orange
substance [probably a complex of germanium(II) oxide
and ethyl ether or germanium(II) hydroxide] precipitated,
and in the liquid phase remained tetraethoxysilane and
ethanol. The following reactions occur apparently under
these conditions:
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Table 2. Calculation results (Gaussian 98, B3LYP/6-31G**) of
thermodynamic parameters for reaction (2)
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Reactions simulation, structure optimization, and
calculation of thermodynamic functions for molecules of
reagents and reaction products was carried out on a PC
Pentium Intel IV/1.9 GHz/RIMM 1 Gb/HDD 80 Gb with
the use of software packages Gaussian 98 [6] and
HyperChem. The designing, modeling, and preliminary
optimization of structures for reagents and reaction
products was performed in the framework of the
software package HyperChem in molecular mechanics
approximation with the use of force field MM+ till attaining
the potential energy minimum with accuracy with respect
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to gradient no less than 10 kcal A° -1 mol-1.
Section simultaneously commands were introduced for
reading structural and frequency characteristics from the
chk-file: # B3LYP/6-31G** Freq (ReadIso, ReadFC)
Geom=Check Guess=Read Test.
The following initial settings and parameters were
introduced into Gaussian 98 for calculation of all molecules
under investigation:
All calculations of molecules under study were
continued till normal completion.
Route Section: # B3LYP/6-31G** Opt=Tight IOp(2/
16=3.2/17=3.2/18=3) Freq,
Data from the out-files were read-out and processed
in MS Excel.
Charge and Multiplicity: 0 1,
Molecule Specification: atomic coordinates calculated
by HyperChem.
The analysis of initial and final products was carried
out on a chromatograph LKhM-80 equipped with a
katharometer, column 2000´2 mm charged with
Chromaton N-AW-DMCS covered with 5% of methyl-
silicone SE-30, carrier gas helium, flow rate 20 ml min-1.
Oven temperature programmed from 20(50) to 300°C at
a rate 16°C/min.
The calculation of thermodynamic parameters at
different temperatures was performed by including into
the calculation of additional steps setting the necessary
characteristics in the window Molecule Specification:
473.0 1.0; 573.0 1.0; 573.0 1.0. Into the field Route
RUSSIAN JOURNALOF ORGANIC CHEMISTRY Vol. 40 No. 5 2004

652
CHERNYSHEV et al.
Table 3. Reaction of MCl4 with M(OR)4
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Table 4. Reaction of SiCl4 with Ge(OR)4
3. Zueva, G.Ya., Serezhkina, N.V., Khaustova, T.I., and Ponoma-
renko, V.A., Izv. Akad. Nauk, SSSR. Ser. Khim., 1978, p. 1185.
4.Mironov,V.F., Issledovaniya v oblasti khimii organicheskikh
soedinenii germaniya (1955–1991 gg) (Researches in
Chemistry of Germanium Organic Compounds), Moscow:
NIITEKhIM, 1991, p. 5.
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5.Chernyshev,E.A.,Komalenkova,N.G.,Tagachenkov,A.A.,
and Bykovchenko, V.G., Zh. Obsch. Khim., 1995, vol. 65, p. 281.
6. Gaussian 98 (Revision A.7), Frisch, M.J., Trucks, G.W.,
Schlegel, H.B., Scuseria, G.E., Robb, M.A., Cheeseman, J.R.,
Zakrzewski, V.G., Montgomery, J.A., Stratmann, R.E., Burant,
J.C., Dapprich, S., Millam, J.M., Daniels,A.D., Kudin, K.N.,
Strain, M.C., Farkas, O., Tomasi, J., Barone, V., Cossi, M.,
Cammi, R., Mennucci, B., Pomelli, C.,Adamo, C., Clifford, S.,
Ochterski, J., Petersson, G.A.,Ayala, P.Y., Cui, Q., Morokuma,
K., Malick, D.K., Rabuck,A.D., Raghavachari, K., Foresman,
J.B., Cios-lowski, J., Ortiz, J.V., Stefanov, B.B., Liu, G.,
Liashenko,A., Piskorz, P., Komaromi, I., Gomperts, R., Martin,
R.L., Fox, D.J., Keith, T., Al-Laham, M.A., Peng, C.Y.,
Nanayakkara, A., Gonza-lez, C., Challacombe, M., Gill,
P.M.W., Johnson, B.G., Chen, W., Wong, M.W.,Andres, J.L.,
Head-Gordon, M., Replogle, E.S., and Pople, J.A., Gaussian
Inc., Pittsburgh PA, 1998.
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Reagent mixtures were charged into a flask with a
ground-glass stopper. A catalyst was added when
necessary. The reaction mixture was maintained at room
temperature, and samples were intermittently analysed.
The results are presented in Tables 3 and 4.
The identification was performed by retention time of
individual compounds.
REFERENCES
1. Mironov,V.F., Gar,T.K., Organicheskie soedineniya krem-
niya (Organic Compounds of Silicon), Moscow: Nauka, 1967,
p. 95.
2. Zueva, G.Ya., Serezhkina, N.V., Khaustova, T.I., and Ponoma-
renko, V.A., Izv. Akad. Nauk, SSSR. Ser. Khim., 1976, p. 912.
RUSSIAN JOURNALOF ORGANIC CHEMISTRY Vol. 40 No. 5 2004