Reaction of the dioxane complex of dichlorogermylene with siloxanes

Article abstract of DOI:10.1023/A:1023455010746

The major organogermanium compounds formed by reactions of the dioxane complex of dichlorogermylene with hexamethyldisiloxane, octamethyltrisiloxane, and hexamethyltricyclotrisiloxane are bis(trimethylsiloxy)dichlorogermane, 3,3-dichloro-1,1,1,5,5,7,7,7-o

Full text of DOI:10.1023/A:1023455010746

Russian Journal of General Chemistry, Vol. 72, No. 12, 2002, pp. 1907 1910. Translated from Zhurnal Obshchei Khimii, Vol. 72, No. 12, 2002,
pp. 2015 2018.
Original Russian Text Copyright
2002 by Shcherbinin, Pushkina, Krivolapova, Bykovchenko, Khromykh, Komalenkova, Chernyshev.
Reaction of the Dioxane Complex
of Dichlorogermylene with Siloxanes
V. V. Shcherbinin, O. Yu. Pushkina, O. V. Krivolapova, V. G. Bykovchenko,
N. N. Khromykh, N. G. Komalenkova, and E. A. Chernyshev
Gosudarstvennyi nauchno-issledovatel’skii institut khimii i tekhnologii elementoorganicheskikh soedinenii
State Research Center of the Russian Federation, Moscow, Russia
Received February 5, 2001
Abstract The major organogermanium compounds formed by reactions of the dioxane complex of di-
chlorogermylene with hexamethyldisiloxane, octamethyltrisiloxane, and hexamethyltricyclotrisiloxane are bis-
(trimethylsiloxy)dichlorogermane, 3,3-dichloro-1,1,1,5,5,7,7,7-octamethyl-3-germa-2,4,6-trioxa-1,5,7-trisila-
heptane, and a cyclic germatetrasiloxane.
In the present work we have studied reactions of the
I + Me3SiOSiMe2OSiMe3
dioxane complex of dichlorogemylene (I) with linear
(hexamethyldisiloxane and octamethyltrisiloxane) and
cyclic (hexamethylcyclotrisiloxane) siloxanes.
X
(3)
(4)
Me3SiOSiMe2CH2GeCl3,
VII
Me3SiOGeCl2OSiMe2OSiMe3.
No reactions of dichlorogermylenes or their com-
plexes with siloxanes have previously been reported.
V
Reactions like (1) and (3) we recently considered
in [1]. Their mechanism involves insertion of :GeCl2
generated from the dioxane complex of dichloroger-
mylene into the C H bond of compounds II and X,
followed by substitution of hydrogen in the GeCl2H
group by chlorine. The conversion of :GeCl2 by this
direction is not too high. The yields of compounds
VII and VIII are as low as 3%.
The reactions of complex I with siloxanes were
performed at 85 95 C. The reaction of complex I
with gexamethyldisiloxane (II) gives three types of
compounds: (1) compounds containing Si O Ge
groups [bis(trimethylsiloxy)dichlorogermane (III), bis-
(trimethylsiloxy)chloromethylgermane (IV), 3,3-di-
chloro-1,1,1,5,5,7,7,7-octamethyl-3-germa-2,4,6-tri-
oxa-1,5,7-trisilaheptane (V), trichlorotrimethylsil-
oxygermane (VI)]; (2) compounds containing C Ge
bonds [1,1,1-trichloro-3,3,5,5,5-pentamethyl-1-germa-
4-oxa-3,5-disilapentane (VII), 1,1,1-trichloro-3,3,5,5,
7,7,7-heptamethyl-1-germa-4,6-dioxa-3,5,7-trisila-
heptane (VIII)]; and (3) organosilicon compounds
[chlorotrimethylsilane, chloropentamethyldisiloxane
(IX), and octamethyltrisiloxane (X)]. The formation of
the latter compound suggests that complex I reacts not
only with compound II, but also with siloxane X.
The most important conversion pathways of :GeCl2
are reactions (2) and (4) which give rise to compounds
III and V.
It should be noted that compounds VII and VIII
results from the reactions of compounds II and X with
dichlorogermylenes formed by decomposition of
complex I, whereas the key role in the synthesis of
compounds III and V belongs not to dichloroger-
mylenes, but to dichlorogermanones (O=GeCl2) which
are close structural and chemical analogs of silanones
(O=SiR2) [2 4].
We propose the following schemes of the reactions
of complex I with compounds II and X.
It is known that germylenes actively react with
oxygen. The rate constant of the reaction of :GeMe2
GeCl2 C4H8O2
I
1
with O2, 2 109 l mol 1 s at 22 C, is 100 times
(1)
(2)
Me3SiOSiMe2CH2GeCl3,
higher that the rate constant of the reaction of :GeMe2
+ Me3SiOSiMe3
VII
Me3SiOGeCl2OSiMe3,
III
1
with 1,3-butadiene (1.24 107 l mol 1 s [5]). The
II
latter reaction is fairly fast and commonly used for
proving germylene formation [6].
1070-3632/02/7212-1907$27.00 2002 MAIK Nauka/Interperiodica

1908
SHCHERBININ et al.
The rate constant of the reaction of :GeCl2 with O2,
Germasiloxanes III and V formed by reactions (5)
and (6) can further react with methylsiloxanes by way
of substitution of chlorine atoms at germanium by
siloxane methyl groups.
lacking in the literature, can be estimated the assump-
tion that it is close to the known rate constant of the
reaction of :GeMe2 with O2. This assumption relies
on the fact that varying substituents in silylenes, the
closest analogs of germylenes, produces no radical
changes in the rate constant. Thus, the rate constants
of the reactions of :SiCl2, :SiMePh, and :SiH2 with O2
II + III
Me3SiOGeCl(Me)OSiMe3
IV
+ Me3SiOSiMe2Cl.
IX
(8)
1
are 3.4 109 [7], 3.0 108 [8], and 7.2 109 l mol 1 s
[9], respectively.
Compounds IV and IX were found among pro-
ducts of the reaction of complex I with compound II.
Thus, the reaction of :GeCl2 with oxygen to form
O=GeCl2 should occur sufficiently fast, since the rate
constant of this reaction should be close to
Germasiloxanes Me3SiOGeMe2(OSiMe2)2OSiMe3
(XI) and Me3SiOGeMe2(OSiMe2)3OSiMe3 (XII)
formed by substitution of both chlorine atoms at
germanium by methyl groups were found among
products of the reaction of octamethyltrisiloxane with
complex I.
1
109 l mol 1 s . However, the reaction rate will be
limited by the rate of feeding oxygen to the reaction
system. To check this assumption, we reacted com-
plex I with hexamethyldisiloxane under two different
conditions of contacting the reaction mixture with air
oxygen.
The yields of germasiloxanes XI and XII are 5
and 1.5%, respectively. The major reaction product is
compound V (yield 23%) which is probably formed
by reaction (6).
The synthesis at a poor contact of the reaction
mixture with air oxygen (in air, without barboting air
through the reaction mixture) was slow, up to 80
90 h (determined by the time of complete decomposi-
tion of complex I). Therewith, the yields of germa-
The reaction of compounds I and II also involves
conversions of the starting siloxane into other sil-
siloxanes III and V were low (5 and 1%, respectively). oxanes. The most intricate stage of such conversions
Because of the low yields of germasiloxanes, we did
not perform detailed analysis of the reaction products.
is siloxane bond cleavage. The mechanism of such
cleavage in the presence of metal chlorides MCln and
HCl has been proposed in the monograph [14]. Ac-
cording to this mechanism, the Si O Si bond reacts
with MCln (in our case, GeCl2) and HCl to form a
six-membered cyclic transition complex which then
decomposes with cleavage of the Si O, Ge Cl, and
H Cl bonds. Such transformation of compound II
gives rise to trimethylsilanol and chlorotrimethylsilane.
To improve the conditions for formation of di-
chlorogermanones and the yield of germasiloxanes,
we barboted air through the reaction mixture
throughout the synthesis. In this case, the synthesis
occurred 2.5 3 times faster (32 h), and the yields of
germasiloxanes III and V improved to 37 and 9%.
Thus, we propose that germasiloxanes III and V
are formed by the following reactions.
H
~
Cl
Me3Si O
~
:GeCl2
II + HCl
Me3Si
Ge Cl
~
II + O=GeCl2
X + O=GeCl2
III,
V.
(5)
(6)
Cl
Me3SiCl + Me3SiOH +:GeCl2.
(9)
Reactions (5) and (6) are likely to be rather fast,
since similar reactions with the closest analogs of
germanones, silanones, are highly exothermic and
rather fast in the liquid phase [10, 11]. Thus, for in-
stance, we estimated the enthalpy [ H0298(g.)] of
O=SiMe2 insertion into hexamethyldisiloxane [reac-
tion (7)] at 372 kJ/mol.
Note that chlorotrimethylsilane was found among
products of the reaction of complex I with siloxane II.
Further reaction of trimethylsilanol with chloro-
silanes present in the reaction mixture is rather fast
and yields new siloxanes. Thus, for instance,
Me3SiOH reacts with compound IX formed by reac-
tion (8) to give octamethyltrisiloxane.
Me3SiOSiMe3 + O=SiMe2
Me3SiOSiMe2OSiMe3. (7)
(10)
Me3SiOSiMe2OSiMe3.
Me3SiOH + IX
HCl
For estimating the enthalpy of reaction (7) we took
the enthalpies of formation [ H0f,298(g.), kJ/mol] of
Me3SiOSiMe3 ( 795 [12]), Me3SiOSiMe2OSiMe3
( 1389 [12]), and O=SiMe2 ( 222 [13]).
It should be noted that chlorosiloxanes may be
formed not only by reaction (8), but also by direct
reaction of methylsiloxanes with :GeCl2.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 12 2002

REACTION OF THE DIOXANE COMPLEX
1909
II + :GeCl2
IX + :GeClMe.
(11)
ion peak. The dioxane complex of dichlorogermylene
was prepared as described in [16].
Reactions of the dioxane complex of dichloroger-
mylene with cyclosiloxanes we studied on an example
of its reaction with gexamethylcyclotrisiloxane (XIII).
In this synthesis, like in the synthesis with linear
siloxanes, complex I generates dichlorogermylene
which then in the presence of air oxygen converts into
dichlorogermanone.
Reaction of the dioxane complex of dichloro-
germylene (I) with hexamethyldisiloxane (II). A
flat-bottomed flask equipped with a magnetic stirrer
and a reflux condenser was charged with 46.3 g of
compound I, 32.4 g of compound II, and 19 g of di-
oxane. The mixture was stirred for 29 h at 85 95 C
with continuous barbotage of air (1 2 ml/min). The
postreaction mixture contained a liquid (81.5 g) and a
solid (10.9 g) phases. The liquid phase was distilled
at atmospheric pressure to isolate 0.6 g of chlorotri-
methylsilane, 36.6 g of dioxane, and 3 g of compound
II. The subsequent vacuum distillation gave 38.5 g of
a fraction containing 24 g of compound III [mass
spectrum, m/e (Irel, %): 307(5) (M Me)+, 219(7) (M
Further dichlorogermanone by a reaction similar to
reactions (5) and (6) inserts into the Si O bond of
cyclosiloxane XIII to form germatetrasiloxane XIV.
SiMe2
O
O
+ :O=GeCl2
Me
SiMe4)+, 139(9) (Me2ClGe)+, 119 (100)
SiMe2
O
O
Me2Si
(Me3Ge)+, 73 (8) (Me3Si)+], 0.5 g of compound IV
[mass spectrum, m/e (Irel, %): 287 (11) (M Me)+,
139 (8) (Me2ClGe)+, 119 (100) (Me3Ge)+, 73 (13)
(Me3Si)+], 7.1 g of compound V [mass spectrum, m/e
(Irel, %): 381 (12) (M Me)+, 293 (4) (M Me
SiMe4)+, 207 (100) (Me5Si3O3)+, 193 (15) (Me3GeO
SiMe2)+, 139 (12) (Me2ClGe)+, 119 (79) (Me3Ge)+,
73 (12) (Me3Si)+], 0.7 g of compound VI, 2.1 g of
compound VII [mass spectrum, m/e (Irel, %): 325
XIII
Me2Si
O
eCl
G
O
eCl
G
2
2
Me2Si
O
XIV
The yield of compound XIV in the reaction of
complex I with compound XIII (32 h, 85 95 C) was
13%. It should be noted that this reaction also gives
various cyclosiloxanes, such as octamethylcyclotetra-
siloxane (XV), decamethylcyclopentasiloxane (XVI),
and dodecamethylcyclohexasiloxane (XVII) (34, 16,
and 6%, respectively). These by-products are probably
formed by reactions like (9) (11) which are induced
by :GeCl2 and HCl, generated in the course of the
synthesis, and lead to Si O Si bond redistribution in
the starting compound XIII.
(100) (M
Me)+, 179 (9) (GeCl3)+, 139 (26)
(GeMe2Cl)+, 73 (19) (Me3Si)+], 1.7 g of compound
VIII [mass spectrum, m/e (Irel, %): 399 (32) (M Me)+,
291 (53) (M Me MeSiCl)+, 205 (33) (M Me
MeGeCl3)+, 119 (100) (Me3Ge)+, 73 (42) (Me3Si)+],
0.9 g of compound IX, and 1.5 g of compound X. The
solid phase contained mostly polymeric germanium
subchlorides (GeClx)n, where x = 1.4 1.5. The yields
of compounds III, V, VII, and VIII (per the starting
compound I) were 37, 9, 3, and 2%.
Reaction of the dioxane complex of dichloro-
germylene (I) with hexamethylcyclotrisiloxane
(XIII). A flat-bottomed flask equipped with a mag-
netic stirrer and a reflux condenser was charged with
11.6 g of compound I, 10.3 g of compound XIII, and
20 g of dioxane. The mixture was stirred for 32 h at
85 95 C with continuous barbotage of air (1
2 ml/min). The postreaction mixture contained a
liquid (37.1 g) and a solid (3.3 g) phases. According
to GC MS, the liquid phase contained 24 g of di-
oxane, 0.22 g of Me3SiCl, 0.28 g of Cl3SiOSiMe3,
2.56 g of compound XIV [mass spectrum, m/e (Irel, %):
367 (21) (M Me)+, 193 (76) (M Me GeCl2Me2)+,
139 (10) (Me2ClGe)+, 119 (100) (Me3Ge)+, 73 (15)
(Me3Si)+], 5.05 g of compound XV, 3.1 g of com-
pound XVI, and 1.42 g of compound XVII. The solid
phase contained mostly polymeric germanium sub-
chlorides (GeClx)n, where x = 1.4 1.5. The yield of
EXPERIMENTAL
Reaction products were analyzed by GC MS. The
mass spectra were obtained on a Hewlett Packard
HP-5971 system at an ionizing voltage of 70 V.
Separation was performed on a DB-5 capillary column
(0.032 2500 cm, film thickness 25 m). The oven
temperature was programmed from 50 to 280 C at a
rate of 7 deg/min; carrier gas helium (0.8 ml/min).
The m/e values are given for the 28Si, 35Cl, and 74Ge
isotopes. The mass spectra were assigned with ac-
count for the mass spectral data for compounds III, V,
and other germasiloxanes, reported in [15]. According
to that work, (1) electron impact induces complete
randomization (intramolecular disproportionation) of
substituents and (2) the mass spectra of compounds
with a central GeCl2 group contain a strong GeMe3+
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 12 2002

1910
SHCHERBININ et al.
compound XIV (per the starting compound XIII) was
13.4%.
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ACKNOWLEDGMENTS
8. Gaspar, P.P., Proc. 7th Int. Symp. on Organosilicon
Chem., Chichester: Harwood, 1985, p. 87.
The work was financially supported by the Russian
Foundation for Basic Research (project no. 99 03-
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