New polyunsaturated silahydrocarbons

Article abstract of DOI:10.1134/S1070363209030086

12-Membered highly unsaturated macrocyclic silahydrocarbon containing exocyclic methyl and benzyl groups is synthesized by the reaction of benzylmethyldi(bromomagnesiumethynyl)silane with dimethyldichlorosilane. Hydrosilylation of benzyl(triethynyl)silane

Full text of DOI:10.1134/S1070363209030086

ISSN 1070-3632, Russian Journal of General Chemistry, 2009, Vol. 79, No. 3, pp. 383–385. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © L.V. Zhilitskaya, N.O. Yarosh, N.K. Yarosh, M.G. Voronkov, 2009, published in Zhurnal Obshchei Khimii, 2009, Vol. 79, No. 3,
pp. 393–395.
New Polyunsaturated Silahydrocarbons
L. V. Zhilitskaya, N. O. Yarosh, N. K. Yarosh, and M. G. Voronkov
Favorskii Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences,
ul. Favorskogo 1, Irkutsk, 664033 Russia
e-mail: voronkov@irioch.irk.ru
Received November 13, 2008
Abstract―12-Membered highly unsaturated macrocyclic silahydrocarbon containing exocyclic methyl and
benzyl groups is synthesized by the reaction of benzylmethyldi(bromomagnesiumethynyl)silane with dime-
thyldichlorosilane. Hydrosilylation of benzyl(triethynyl)silane with trichlorosilane with subsequent reaction of
the formed adduct with trimethylsilylmagnesium bromide leads to the spherical dendrimer (NC = 3) containing
the benzyl group at the central Si atom, –СН=СН– groups in the inner sphere and numerous triple bonds on the
periphery. NMR spectra of the obtained compounds were studied.
DOI: 10.1134/S1070363209030086
intensity. In the mass spectrum the peak of ion with m/z
91(26) is observed, which has the structure of tropy-
lium cation as indicated by the presence of the peak of
cyclopentadienyl cation with m/z 65(10) formed after
elimination of acetylene molecule from the ion with m/z
91. The abstraction of trimethylsilyl group from [М+]
is a general route of fragmentation of macrocyclic
silahydrocarbons [11]. Other characteristic processes
of fragmentation are weakly pronounced (Table 1).
In continuation of our studies of polyunsaturated
macrocyclic and dendrimer silahydrocarbons [1–9] we
have synthesized new representatives of these classes
of compounds. For their design we have used
benzylmethyl(diethynyl)- and benzyl(triethynyl)silane
as synthons [10].
By the reaction of benzylmethyl(diethynyl)silane
with ethylmagnesium bromide and dimethyldichloro-
silane in the molar ratio of 2:4:2 in the mixture of ether
and tetrahydrofuran under the conditions of high
dilution the 12-membered highly unsaturated macro-
cyclic silahydrocarbon containing exocyclic methyl
and benzyl groups, 1,4,4,10,10-hexamethyl-1,7-dibenzyl-
1,4,7,10-tetrasilacyclododeca-2,5,8,11-tetrayne (I) has
been synthesized in 12% yield (Scheme 1).
The two-step synthesis: hydrosilylation of benzyl
(triethynyl)silane with trichlorosilane and the sub-
sequent reaction of the formed adduct with trime-
thylsilylmagnesium bromide (1:3:9) affords in 30%
yield the three-branched organosilicon dendrimer con-
taining a benzyl group at the central silicon atom, three
–СН=СН– groups in the inner sphere and numerous
С≡С triple bonds on the periphery, benzyltris[tris(trime-
thylsilylethynyl)silylvinyl]silane (II) (Scheme 2).
In the mass spectrum of compound I the peak of the
molecular ion is present. Its fragmentation proceeds
with the expulsion of either methyl or benzyl radical
giving rise, in the latter case, to the peak of maximum
Scheme 1.
Me
Si1 C
C
Me
Si2 Me
CH2
C
C
C
C
Si(C CH)2 + 4 EtMgBr + 2 Me2SiCl2
Me
2
C
Me Si
Me
C
Si
CH2
Me
I
383

384
ZHILITSKAYA et al.
Found, %
Table 1. Constants of synthesized compounds I, II
Calculated, %
H
Comp.
no.
Yield,
%
mp,
°C
Formula
C
H
Si
C
Si
Ia
11
30
186–187
146–148
68.65
58.91
6.12
8.07
22.87
30.50
C28H32Si4
C58H94Si13
69.93
60.23
6.70
8.19
23.36
31.58
II
Mass spectrum, m/z , ion: 480(3), [M]+; 465(2), [M – 15]+; 389(100), [M – С7Н7]+; 316(4), [M – 164]+; 97(7), [C≡CSiMe3]+; 91(26),
a
[С7Н7]+; 83(14), [C≡CSiMe2Н]+; 73(48), [SiMe3]+.
Table 2. 1H, 13C, 29Si NMR spectra of synthesized compounds I, II
29Si NMR spectrum,
1Н NMR spectrum, δ, ppm
13С NMR spectrum, δС, ppm
С6Н5 Si1Me Si2Me СН=СН C≡C СН2
δSi, ppm
Comp.
no.
СН=СН,
Si1Me Si2Me
СН2
2.35 7.2 (m) –3.74 –1.29
С6Н5
Si1
Si2
Si3
–
(J, Hz)
0.22
0.34
–
–
115.41, 24.52 124.63(р), –42.06 –42.56
I
112.64
127.98(о),
128.36(m),
0.05
–
2.20 6.83 (m) –0.31
–
149.16,
23.17 136.62(i)
124.31(р),
–16.01 –76.71 –60.44
II
147.19 115.86,
104.01
127.07(о),
6.31 d,
6.44 d,
127.95(m),
144.51(i)
(Jtrans 21.77)
Scheme 2.
Si(CH CHSiCl3)3
Si(C CH)3 + 3 HSiCl3
Me
Me
Me
Me
Si
Me
Si Me
C
C
C
CH2
CH 1Si CH
C
C
Me
3Si Me
Me
9 BrMgC
CSiMe3
Me Si
Me
C
C
Si CH
CH 2Si
C
C
Me
C
C
CH
CH
Si
C
Si
Si
Me
Me
Me
Me
Me
Me
C
C
C
C
C
C
Si
Me
Me
Me Si
Si
Me
Me
Me
Me
Me
Me
II
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 3 2009

385
NEW POLYUNSATURATED SILAHYDROCARBONS
Some key parameters of dendrimer II having
regular structure were determined [12]. The number of
generation G = 1; index of branching or the number of
dendrons growing from the core, NС = 3; index of
branching of the units, the number of branches formed
by each of the repeated units NB = 3. The number of
terminal groups: Z = NCNGB = 9.
Benzyltris[tris(trimethylsilylethynyl)silylvinyl]-
silane (II). To 1.94 g of benzyl(triethynyl)silane and
0.1 ml of 0.2 N solution of H2PtCl6 4.06 g of trichloro-
silane was added dropwise at stirring. The mixture was
kept for 1 h at 90°С, then cooled and the Iotsitch
reagent prepared from 2.4 g of Mg, 10.9 g of EtBr and
9.8 g of trimethylethynylsilane in 100 ml of THF was
added dropwise. After heating to 45°С during 30 min
the mixture was decomposed with water and 5% HCl.
Further treatment was similar to that described above.
After removal of solvents 3.4 g (30%) of compound II
was isolated by crystallization from hot hexane.
The degree of polymerization and theoretical mass
cannot be calculated using the earlier employed
method since dendrimer II simultaneously contains in
the chain the bonds of different multiplicity.
The synthesized polyunsaturated silahydrocarbons
I, II are crystalline compounds stable at storage,
soluble in organic solvents. Their yields and physico-
chemical constants are given in Table 1 and their
ACKNOWLEDGMENTS
This work was performed with financial support
from the Council of grants of the President of RF
(grant No. NSh-255-2008.3) and integration project
“Creation of new carbon-silicon composite materials.”
1
structure is proved by the data of Н, 13С and 29Si
NMR spectroscopy (Table 2).
The presence of numerous multiple bonds in the
molecules I, II provides wide possibilities for their use
as precursors of more complex nanodimensional
structures.
REFERENCES
1. Voronkov, M., Yarosh, O., and Zhilitskaja, L.,
Phosphorus, Sulfur and Silicon, 1992, vol. 65, p. 33.
2. Voronkov, M.G., Yarosh, O.G, and Turkina, G.Yu.,
J. Organomet. Chem., 1995, vol. 491, nos 1–2, p. 215.
EXPERIMENTAL
NMR spectra were registered on a Bruker DRX 400
instrument (400 MHz) for 15% solutions in CDCl3
with HMDS as an internal reference. Mass spectrum
3. Yarosh, O.G., Voronkov, M.G., and Brodskaya, E.I.,
Russ. Chem. Rev., 1995, vol. 64, no. 9, p. 839.
4. Yarosh, O.G., Zhilitskaya, L.V., Istomina, E.E.,
Yarosh, N.K., Albanov, A.I., and Voronkov, M.G.,
Russ. J. Gen. Chem., 2005, vol. 75, no. 7, p 1094.
5. Zhilitskaya, L.V., Istomina, E.E., Yarosh, N.O., and
Voronkov, M.G., Russ. J. Gen. Chem., 2006, vol. 76,
no. 8, p 1261.
was obtained on
a LKB 2091 chromatomass
spectrometer using the system of direct injection into
the ion source, ionizing voltage 60 eV, the temperature
of the source 250°С.
All solvents used in this work were thoroughly dried.
6. Zhilitskaya, L.V., Istomina, E.E., Yarosh, N.O., Voron-
kov, M.G., Albanov, A.I., and Yarosh, O.G., Russ. J.
Gen. Chem., 2006, vol. 76, no. 12, p. 1864.
7. Zhilitskaya, L.V., Yarosh, N.K., Istomina, E.E., and
Voronkov, M.G., Russ. J. Gen. Chem. 2007, vol. 77,
no. 10, p. 1718.
8. Zhilitskaya, L.V., Yarosh, N.K., Istomina, E.E., Voron-
kov, M.G., and Albanov, A.I., Russ. J. Gen. Chem.,
2007, vol. 77, no. 11, p. 1887.
1,4,4,10,10-Hexamethyl-1,7-dibenzyl-1,4,7,10-
tetrasilacyclododeca-2,5,8,11-tetrayne (I). To 50 ml
of dry ether, benzylmethyldi(bromomagnesiumethynyl)-
silane prepared from 1 g of Mg, 4.4 g of EtBr and
3.68 g of benzylmethyl(diethynyl)silane in 75 ml of
THF and, simultaneously, 2.6 g of dimethyldichloro-
silane in 50 ml of ether were added dropwise with
stirring. After mixing for 1 h the mixture was decom-
posed with water and 5% HCl. Aqueous layer was
separated in a separating funnel and thrice extracted
with ether in portions of 30 ml. The ether extracts were
combined with the main organic layer and dried over
calcinated CaCl2. The dryer was filtered off, twice
washed with dry ether in portions of 30 ml, and the
solvent was distilled off under reduced pressure
(water-jet pump). From the residue, 1.06 g (11%) of
compound I was isolated by sublimation in a high
vacuum (10–3 mm Hg) (Table 1).
9. Zhilitskaya, L.V., Yarosh, N.O., and Voronkov, M.G.,
Russ. J. Gen. Chem., 2008, vol. 78, no. 10, p. 1889.
10. Zhilitskaya, L.V., Yarosh, N.K., Yarosh, N.O., and
Voronkov, M.G., Russ. J. Gen. Chem., 2008, vol. 78,
no. 1, p. 69.
11. Yarosh, O.G., Zhilitskaya, L.V., Yarosh, N.K., Alba-
nov, A.I., and Voronkov, M.G., Russ. J. Gen. Chem.,
2004, vol. 74, no. 10, p. 1492.
12. Semchikov, Yu.D., Soros. Obraz. Zh., 1998, no. 12,
p. 45.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 3 2009