Hexa(organylsilsesquioxanes)

Article abstract of DOI:10.1007/s11172-016-1409-9

A method for the synthesis of earlier practically unknown hexa(organylsilsesquioxanes) (RSiO_1,5)₆ have been developed based on the reaction of organyltrichlorosilanes RSiCl₃ (R = Et, Vin) with DMSO. The reaction proceeded in several steps. The initial stage of the reaction gave poorly available 1,3,5-trichloro-1,3,5-triorganylcyclosiloxanes in 40—80% yield, as well as organyl(chloro)oligohomosilsesquioxanes, which further are converted to the corresponding organyloligosilsesquioxanes. Based on the monitoring of the reaction mixture by GC-MS, a scheme for the formation of the intermediate silsesquioxane structures have been suggested.

Full text of DOI:10.1007/s11172-016-1409-9

Russian Chemical Bulletin, International Edition, Vol. 65, No. 4, pp. 1034—1038, April, 2016
1034
Hexa(organylsilsesquioxanes)*
S. V. Basenko and A. A. Maylyan
A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences,
1 ul. Favorskogo, 664033 Irkutsk, Russian Federation.
Eꢀmail: sv_basenko@irioch.irk.ru
A method for the synthesis of earlier practically unknown hexa(organylsilsesquioxanes)
(RSiO1,5)6 have been developed based on the reaction of organyltrichlorosilanes RSiCl3 (R = Et,
Vin) with DMSO. The reaction proceeded in several steps. The initial stage of the reaction gave
poorly available 1,3,5ꢀtrichloroꢀ1,3,5ꢀtriorganylcyclosiloxanes in 40—80% yield, as well as
organyl(chloro)oligohomosilsesquioxanes, which further are converted to the corresponding
organyloligosilsesquioxanes. Based on the monitoring of the reaction mixture by GCꢀMS,
a scheme for the formation of the intermediate silsesquioxane structures have been suggested.
Key words: organyltrichlorosilanes, dimethyl sulfoxide, organyl(chloro)silanones, organylꢀ
(chloro)cyclosiloxanes, organylsilsesquioxanes.
Organylsilsesquioxanes of caged structure (RSiO1,5)n,
through the intermediate generation of organyl(chloro)ꢀ
silanones 1 (Scheme 1), with further cyclotrimerization to
organyl(chloro)cyclotrisiloxanes 2, which are the basis for
the formation of hexasilsesquioxane structure 3.
especially octa(organylsilsesquioxanes) (n = 8), are the
basis for the synthesis of octopusꢀlike molecules,1 organoꢀ
silicon dendrimers,2 and resins. They are suggested as
radiationꢀsensitive materials for dry vacuum submicron
lithography.3 They are traditionally synthesized by hyꢀ
drolysis of the corresponding organyltrichlorosilanes
RSiCl3 (R = Me, Et, Vin) in organic solvents. These conꢀ
ditions predominantly lead to octa(organylsilsesquioxanꢀ
es). Hexa(organylsilsesquioxanes) are formed in trace
amounts.4—6
Scheme 1
Earlier, we have shown that the use of DMSO as oxyꢀ
genation agent allows one to predominantly effect the synꢀ
thesis of small cycles.7—9 Thus, the reaction of Me2SiCl2
with DMSO gives hexamethylcyclotrisiloxane as the main
reaction product (48—85%),7—10 whereas hydrolysis of
Me2SiCl2 leads to tetramethylcyclotetraꢀ and pentamethꢀ
ylcyclopentasiloxanes.11—12
The attempts to obtain hexa(vinylsilsesquioxane) by
a combination of two methods (the use of the oxygenꢀ
ation reagent (DMSO) and subsequent hydrolysis of
the reaction mixture in chloroform) led, according to the
authors,13 to the formation of a mixture of unidentified
products.
We found the condition for the synthesis of hexaꢀ
(organylsilsesquioxanes) with ethyl and vinyl substituents
at the silicon atom by the reaction of ethylꢀ and vinylꢀ
trichlorosilanes, respectively, with DMSO in organic solꢀ
vents (CHCl3, diethyl ether, toluene, etc.) under argon in
11—15% yield. The reaction, as we suggest, proceeds
R = Et (a), Vin (b)
Cyclic organylchlorosiloxanes (RClSiO)n (R = Et, Vin,
n = 3) are poorly available compounds. This largely limits
their application as synthons in organic and organoeleꢀ
ment chemistry. Before our studies,14 a method for the
preparation of (EtClSiO)3 based on the chlorination of
preliminary synthesized ethylcyclotrisiloxane (EtHSiO)3
has been described.15
* Based on the materials of the XIII Andrianov Conference
"Organosilicon Compounds: Synthesis, Properties, and Appliꢀ
cation" (June 28—July 1, 2015, Moscow).
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 1034—1038, April, 2016.
1066ꢀ5285/16/6504ꢀ1034 © 2016 Springer Science+Business Media, Inc.

Hexa(organylsilsesquioxanes)
Russ.Chem.Bull., Int.Ed., Vol. 65, No. 4, April, 2016
1035
Scheme 2
Note that the content of 1,3,5ꢀtrichloroꢀ1,3,5ꢀtrivinꢀ
ylcyclotrisiloxane (2b) in the reaction mixture compared
to 1,3,5ꢀtrimethylꢀ14 and 1,3,5ꢀtriethylꢀsubstituted cycloꢀ
trisiloxanes considerably differs. The yield of cyclosiloxane
2b in the reaction of VinSiCl3 with an equimolar amount
of DMSO at 0 °C in organic solvents (CHCl3, diethyl
ether, mꢀxylene, toluene) does not exceed 35—40%,
whereas in similar reaction with EtSiCl3, the yield of the
cyclic derivatives reaches almost 80%.
The monitoring of the reaction of VinSiCl3 with
DMSO (molar ratio 1 : 1, 0 °C) in organic solvents
(CHCl3, diethyl ether) by GCꢀMS was carried out immeꢀ
diately after mixing the reagents and then every 6—24 h. It
was identified about a dozen reaction products, including
those formed in insignificant amounts (2—5%). Thus, the
formation of linear and cyclic siloxanes is observed in the
initial stage of the reaction. In the case of trichlorovinylꢀ
silane these products mainly are 1,1,3,3ꢀtetrachloroꢀ1,3ꢀ
divinyldisiloxane and 1,3,5ꢀtrichloroꢀ1,3,5ꢀtrivinylcycloꢀ
trisiloxane. The presence of 1,1,3,5,5ꢀpentachloroꢀ1,3,5ꢀ
trivinyltrisiloxane in the reaction mixture is observed for
a long time, until the formation of the silsesquioxane strucꢀ
ture is completed, however, its yield in any of the steps did
not exceed 7—11%.
Apart from that, already in the initial stage of the reacꢀ
tion, the formation of chloro(vinyl)oligohomosilsesꢀ
quioxanes 4b—9b is observed together with the linear and
cyclic chlorovinylsiloxanes (Schemes 2—4), whereas the
target hexa(vinylsilsesquioxane) 3b is formed after standꢀ
ing of the reaction mixture during 48—96 h. Even when
DMSO is taken in less than equimolar amount, the cyclizꢀ
ation process for trichlorovinylsilane does not stop in the
step of the formation of chlorocyclosiloxane 2b, rather it
continues to form (VinSiO1,5)6 and a number of unfinꢀ
ished (chloro(vinyl)oligohomosilsesquioxane) structures.
In the reaction of EtSiCl3 with DMSO (molar ratio 1 : 1,
0 °C) the formation of such structures is observed when
the reaction mixture is allowed to stand for a longer time
(2—3 weeks) and accelerates only upon addition of DMSO
to the reaction mixture.
No intermediate formation of structures with hydroxy
groups was observed in the course of monitoring. The main
terminal elements of condensed structures in all the stagꢀ
es of our observation (together with a vinyl group) were
chlorine atoms.
In contrast to the hydrolytic methods for the synꢀ
thesis of silsesquioxanes, no processes of cleavage and
rearrangement with the formation of complex and
Scheme 3

1036
Russ.Chem.Bull., Int.Ed., Vol. 65, No. 4, April, 2016
Basenko and Maylyan
Table 1. The mass spectrometry data for intermediate chloro(vinyl)oligohomosilsesquioxanes
Ion
m/z* (Irel(%))
4b
5b
6b
7b
8b
9b
11b
M+.
582 (2)
528 (8)
501 (100)
493 (11)
487 (54)
475 (44)
461 (9)
449 (19)
1—
423 (10)
1—
397 (19)
1—
476 (12)
449 (82)
441 (24)
435 (100)
423 (62)
409 (21)
397 (30)
383 (19)
371 (17)
1—
422 (1)
395 (100)
387 (6)
1—
369 (7)
1—
343 (13)
1—
317 (8)
1—
580 (9)
553 (100)
545 (3)
539 (2)
527 (13)
513 (2)
501 (16)
487 (1)
475 (2)
461 (1)
449 (1)
1—
686 (17)
659 (100)
651 (9)
645 (19)
1—
619 (13)
607 (32)
1—
581 (10)
1—
555 (24)
541 (6)
117 (5)
91 (5)
738 (75)
711 (100)
1—
597 (23)
685 (41)
1—
1—
1—
1—
619 (24)
1—
[M – Vin]+
555 (17)
547 (15)
541 (15)
527 (40)
515 (16)
503 (27)
489 (30)
477 (15)
463 (19)
451 (8)
M – Cl]+
[M – Vin – CH2]+
[M – Vin – C2H2]+
[M – Vin – C2H2 – CH2]+
[M – Vin – 2 C2H2]+
[M – Vin – 2 C2H2 – CH2]+
[M – Vin – 3 C2H2]+
[M – Vin – 3 C2H2 – CH2]+
[M – Vin – 4 C2H2]+
[M – Vin – 4 C2H2 – CH2]+
Vin2SiCl
345 (12)
1—
117 (23)
191 (7)
291 (2)
1—
1—
437 (9)
117 (100)
191 (42)
1—
1—
191 (57)
1—
191 (1)
117 (1)
191 (1)
VinHSiCl
191 (1)
* Calculated on isotope 35Cl. The ratio of intensities of isotope peaks corresponds to the calculations.
more strained cyclosiloxane molecules were observed
in our case.
Octa(vinylsilsesquioxane) (10b) is also observed among
the reaction product, however, its yield did not exceed
4—5%. The detection in the mass spectra of the interꢀ
mediate chloro(vinyl)oligohomosilsesquioxane structures
(8b and 9b), the formation of which can be explained by
a sequential incorporation of chloro(vinyl)silanone, inꢀ
volving, as we assume, in the processes of the formation of
silsesquioxane structures, allows us to suggest Scheme 4
for the formation of (VinSiO1,5)8.
Based on the data obtained (Table 1), the followꢀ
ing scheme for the synthesis of hexa(organylsilsesquiꢀ
oxanes) can be suggested, which consists in the sequenꢀ
tial condensation of cyclic molecules involving DMSO
(Scheme 2).
A relatively stable structure 7b observed in an insignifꢀ
icant amount practically all the time of reaction moniꢀ
toring, probably, is an unfinished pyramid formed accordꢀ
ing to Scheme 3.
The initial step of further transformation of
(VinSiO1,5)8 was also identified (Scheme 5).
Scheme 4

Hexa(organylsilsesquioxanes)
Russ.Chem.Bull., Int.Ed., Vol. 65, No. 4, April, 2016
1037
Scheme 5
over melted KOH, after decantation it was frozen out and disꢀ
tilled in vacuo. Their physical constants agreed with the literaꢀ
ture data.
Reaction of trichlorovinylsilane with DMSO. A solution of
DMSO (7.8 g, 0.1 mol) in chloroform was slowly (over 1 h)
added to a solution of trichlorovinylsilane (16.0 g, 0.1 mol) at
0 °C in chloroform under argon. The mixture was stirred for 6 h
and distilled in vacuo. The following products were isolated:
1,3ꢀtetrachloroꢀ1,3ꢀdivinyldisiloxane, 1,1,3,5,5ꢀpentachloroꢀ
1,3,5ꢀtrivinyltrisiloxane, compounds 2b and 3b.
1,3ꢀTetrachloroꢀ1,3ꢀdivinyldisiloxane. The yield was 1.8 g
(14%), b.p. 51—52 °C (2 Torr). Found (%): C, 17.57; H, 2.19;
Cl, 52.49; Si, 21.18. C4H6Cl4OSi2. Calculated (%): C, 17.92;
H, 2.26; Cl, 52.90; Si, 20.95. 1H NMR, δ: 6.10 (dd, 2 H,
3
3
SiCH=CH2, Jci3s = 14.5 Hz, Jtrans = 20.3 Hz); 6.35 (dd, 2 H,
2Jgem = 5.2 Hz, Jtrans = 14.3 Hz), 6.28 (dd, 2 H, SiCH=CH2,
Hexa(organylsilsesquioxanes) were isolated from the reꢀ
action precipitate by sublimation in vacuo (10–1—10–2 Torr)
at 100—150 °C. Sublimation of octa(organylsilsesquiꢀ
oxanes) was observed at the temperatures of 150—200 °C.
The GCꢀMS analysis data showed some details of the
disintegration of hexa(organylsilsesquioxanes).
The mass spectrum of (EtSiO1,5)6 (3a) somewhat difꢀ
fers from the spectrum of (EtSiO1,5)8. First of all, by the
presence of the molecular ion M+ with m/z 486, the second
in intensity after the [M – Et]+ ion with m/z 457. It should
be also noted a low intensity of the doubly charged ion
[M – 2 Et]2+ with m/z 214, as well as the presence of
relatively strong ions formed by a sequential elimination
of neutral fragments C2H4 and C2H6 against the backꢀ
ground of weak (0.1—1%) linear ions formed, apparently,
by the loss of CH2 and CH4 groups from the ethyl subꢀ
stituents.
2Jgem = 5.2 Hz, Jtrans = 20.3 Hz). 13C NMR, δ: 135.75, 135.97,
3
136.11, 136.54, 136. 79, 137.60. 29Si NMR, δ: –30.85. MS,
m/z (Irel (%)): 266(1) [M]+, 239 (28) [M – Vin]+, 231 (100)
[M – Cl]+, 213 (39) [M – Vin – C2H2]+, 203 (33) [M – Vin –
– HCl]+, 179 (46) [HCl2SiOSiClH]+, 115 (17) [HCl2SiO]+,
99 (4) [HCl2Si]+.
1,3,5ꢀTrichloroꢀ1,3,5ꢀtrivinylcyclotrisiloxane (2b). The yield
was 4.2 g (40%), b.p. 129—131 °C (2 Torr). Found (%): C, 22.34;
H, 2.77; Cl, 32.91; Si, 26.17. C6H9Cl3O3Si3. Calculated (%):
1
C, 22.54; H, 2.82; Cl, 33.33; Si, 26.29. H NMR, δ: 6.10—6.35
(m, 18 H, CH=CH2). 13C NMR, δ: 135.75—137.60 (CH=CH2).
29Si NMR, δ: –45.06. MS, m/z (Irel (%)): 318 (6) [M]+, 291 (68)
[M — Vin]+, 283 (100) [M – Cl]+, 277 (23) [M – Vin – CH2]+,
265 (53) [M – Vin – C2H2]+, 257 (74) [M – Cl – C2H2]+, 239
(52) [M – Vin – 2 C2H2]+, 229 (47), 219 (7), 205 (31) [M – Cl –
– 3 C2H2]+, 194 (12), 167 (6), 159 (5), 134 (2), 123 (3)
[VinClSiO(OH)]+, 107 (2) [VinClSiOH]+, 80 (35) [HClSiO]+,
66 (19), 54 (17), 49 (3).
1,1,3,5,5ꢀPentachloroꢀ1,3,5ꢀtrivinyltrisiloxane. The yield
was 1.3 g (10%), b.p. 101—102 °C (2 Torr). Found (%): C, 19.56;
H, 2.29; Cl, 47.19; Si, 22.28. C6H9Cl5O2Si3. Calculated (%): C,
19.33; H, 2.42; Cl, 47.65; Si, 22.55. 29Si NMR, δ: –31.97
(VinCl2SiO), –55.17 (OVinClSiO). MS, m/z (Irel (%)): 372 (1)
[M]+, 345 (8) [M – Vin]+, 337 (100) [M – Cl]+, 319 (10)
[M – Vin – C2H2]+, 309 (22) [M – Vin – HCl]+, 283 (8)
[M – Vin – HCl – C2H2]+, 247 (2) [M – Vin – 2 HCl – C2H2]+,
179 (2) [HCl2SiOSiClH]+, 145 (2) [H2ClSiOSiClH]+, 115 (15)
[HCl2SiO]+, 99 (2) [HCl2Si]+, 80 (14) [HClSiO]+.
Chloromethyl methyl sulfide 8.7 g (89%) was collected in
the cooled trap, which after distillation under atmospheric presꢀ
sure had the following constants: b.p. 109—110 °C (cf. data
Ref. 18: b.p. 110—112 °C), nD20 1.4955.
Hexa(vinylsilsesquioxane) (3b) was isolated from the reacꢀ
tion precipitate by sublimation in vacuo (10–1—10–2 Torr) at
100—140 °C. The yield was 1.2 g (15%). Found (%): C, 29.99;
H, 3.69; Si, 35.21. C12H18O9Si6. Calculated (%): C, 30.35;
H, 3.79; Si, 35.51. 29Si NMR, δ: –71.40. MS (VinSiO1,5)6: 474
(100) [M]+, 447 (80) [M – Vin]+, 433 (3) [M – Vin – CH2]+,
421 (18) [M – Vin – C2H2]+, 419 (11) [M – Vin – C2H4]+, 409 (9),
403 (1) [M – VinSiO]+, 393 (3) [M – Vin – C2H4 – C2H2]+,
377 (23) [M – VinSiO – C2H2]+, 351 (3) [M – VinSiO – 2 C2H2]+,
349 (2) [M – VinSiO – C2H4 – C2H2]+, 323 (2) [M – VinSiO –
– C2H4 – 2 C2H2]+, 306 (1) [M – 2 VinSiO – C2H2]+, 297 (2)
[M – VinSiO – C2H4 – 3 C2H2]+, 295 (2) [M – VinSiO –
– 2 C2H4 – 2C2H2]+, 278 (1), 271 (1) [M – VinSiO – C2H4 –
The molecular ion M+ with m/z 474 in the mass specꢀ
trum of (VinSiO1,5)6 (2b) is the strongest in contrast to the
spectrum of (VinSiO1,5)8, in which it has the fourth intenꢀ
sity. The spectrum also exhibits the [M – Vin – C2H2 –
– CH2 – OSiCH2]+ ion with m/z 349, which for (VinSiO1,5 8
)
indicates the disintegration of the siloxane framework,16
however, its intensity is lower.
In conclusion, we have developed a new method for
the synthesis of actually earlier unknown hexa(organylꢀ
silsesquioxanes) and used GCꢀMS monitoring of the reacꢀ
tion mixtures to suggest a scheme of their formation.
Experimental
1
H, 13C, and 29Si NMR spectra were recorded on a Bruker
DPX 400 spectrometer (400, 100.13, 79.49 MHz, respectively)
in CDCl3, using SiMe4 as an internal standard. Mass spectra
were recorded on a Shimadzu GCMSꢀQP5050A spectrometer,
injector temperature 200—250 °C, carrier gas helium, detector
temperature 200 °C, a quadrupole mass analyzer, EI ionization
(70 eV). Elemental analysis (C, H) was carried out on a FLASH
EA 1112 Series analyzer. The content of chlorine and silicon
was analyzed using the Gel´man procedure.17
Trichloroethylsilane and trichlorovinylsilane are industrial
products purified by distillation. Dimethyl sulfoxide was stored

1038
Russ.Chem.Bull., Int.Ed., Vol. 65, No. 4, April, 2016
Basenko and Maylyan
– 4 C2H2]+., 237 (3), 224 (5), 211 (4), 210 (2) [M – 2 Vin]2+
197 (6), 170 (4), 158 (2).
,
3. T. N. Martynova, V. P. Korchkov, J. Organomet. Chem.,
1983, 248, 241.
Octa(vinylsilsesquioxane) was sublimated at 10–1—10–2 Torr
and temperature 150—200 °C in 4% yield (0.3 g). Its mass specꢀ
trum agrees with that published earlier.19
4. K. Olsson, K. Axen, Arkiv Kemi, 1963, 22, 237.
5. K. A. Andrianov, N. M. Petronina, T. V. Vasil´eva, V. E.
Shklover, B. Zh. D´yachenko, Zh. Obshch. Khim., 1978, 48,
2692 [J. Gen. Chem. USSR (Engl. Transl.), 1978, 48].
6. M. G. Voronkov, V. I. Lavrent´yev, Top. Curr. Chem., 1982,
102, 199.
Reaction of trichloroethylsilane with DMSO was carried out
similarly to obtain the following products: 1,3ꢀtetrachloroꢀ1,3ꢀ
diethyldisiloxane, compounds 2a and 3a.
1,3ꢀTetrachloroꢀ1,3ꢀdiethyldisiloxane. The yield was 12%,
b.p. 41—42 °C (2 Torr) (cf. Ref. 20: 186—187 °C (757 Torr)).
1H NMR, δ: 1.11 (CH2); 1.02 (CH3). 13C NMR, δ: 13.33 (CH2);
5.92 (CH3). 29Si NMR, δ: –15.20.
7. S. V. Basenko, M. G. Voronkov, Dokl. Akad. Nauk, 1994,
339, 486 [Dokl. Chem. (Engl. Transl.), 1994].
8. M. G. Voronkov, S. V. Basenko, J. Organomet. Chem., 1995,
500, 325.
1,3,5ꢀTrichloroꢀ1,3,5ꢀtriethylcyclotrisiloxane (2a). The yield
was 74%, b.p. 121—122 °C (2 Torr), nD20 1.2585 (cf. Ref. 15: b.p.
126—127 °C (2 Torr), nD20 1.2591). Found (%): C, 21.87; H, 4.19;
Cl, 32.49; Si, 26.16. C6H15Cl3O3Si3. Calculated (%): C, 22.12;
H, 4.61; Cl, 32.72; Si, 25.81. 29Si NMR, δ: –30.59.
9. M. G. Voronkov, S. V. Basenko, Silanony. Ot efemerov k
monomeram, oligomeram i polimeram [Silanones. from Ephemꢀ
ers to Monomers, Oligomers, and Polymers], Novosibirsk, Geo
Academ. Rubl., 2014, 142 pp. (in Russian).
10. C. Le Roux, H. Yang, S. Wenzel, S. Grigoras, M. A. Brook,
Organometallics, 1998, 17, 556.
11. W. I. Patnode, D. F. Wilcock, J. Am. Chem. Soc., 1946,
68, 358.
12. K. A. Andrianov, Metody elementoorganicheskoi khimii [Meꢀ
thods of Organoelement Chemistry], Nauka, Moscow, 1968,
396 (in Russian).
13. A. R. Bassindale, I. A. MacKinnon, M. G. Maesano, P. G.
Taylor, Chem. Commun., 2003, 1382.
14. S. V. Basenko, M. G. Voronkov, I. A. Gebel, Russ. Chem.
Bull. (Int. Ed.), 2000, 49, 363 [Izv. Akad. Nauk, Ser. Khim.,
2000, 361].
15. N. N. Sokolov, S. M. Akimova, Zh. Obshch. Khim., 1956, 26,
2276 [J. Gen. Chem. USSR (Engl. Transl.), 1956, 26].
16. M. G. Voronkov, V. I. Lavrent´ev, A. N. Kanev, V. G. Kosꢀ
trovskii, S. A. Prokhorova, Dokl. Akad. Nauk SSSR, 1979,
249, 106 [Dokl. Chem. (Engl. Transl.), 1979].
The mass spectrometric data data of synthesized 1,3ꢀtetraꢀ
chloroꢀ1,3ꢀdiethyldisiloxane and 1,3,5ꢀtrichloroꢀ1,3,5ꢀtriethylꢀ
cyclotrisiloxane (2a) agree with those published earlier.14
Hexa(ethylsilsesquioxane) (3a) was isolated from the reacꢀ
tion precipitate by sublimation in vacuo at 10–1—10–2 Torr and
100—150 °C. The yield was 1.0 g (12%). Found (%): C, 29.87;
H, 6.19; Si, 35.03. C12H30O9Si6. Calculated (%): C, 29.60; H, 6.17;
Si, 34.64. 29Si NMR, δ: –56.93. MS (EtSiO1,5)6: 486 (24) [M]+,
457 (100) [M – Et]+, 429 (10) [M – Et – C2H4]+, 401 (3)
[M – Et – 2 C2H4]+, 385 (2) [M – Et – C2H4 – C2H6 – CH2]+,
373 (2) [M – Et – 3 C2H4]+, 372 (3) [M – 3 C2H4 – C2H6]+,
357 (2) [M – Et – 2 C2H4 – C2H6 – CH2]+, 345 (2) [M – Et –
– 4 C2H4]+, 344 (5) [M – 4 C2H4 – C2H6]+, 330 (6) [M –
– 4 C2H4 – CH2 – C2H6]+, 316 (5) [M – 5 C2H4 – C2H6]+,
299 (2), 285 (1), 271 (1), 234 (2), 215 (2), 214 (<1), 200 (5),
186 (3), 172 (3), 157 (2).
17. N. E. Gel´man, Metody kolichestvennogo organicheskogo
elementnogo mikroanaliza [Methods of Quantitative Organic
Elemental Microanalysis], Khimiya, Moscow, 1987, 296 pp.
(in Russian).
18. H. Bohme, H. Fisher, R. Frank, Lieb. Ann., 1949, 563, 54.
19. M. G. Voronkov, T. N. Martynova, R. G. Mirskov, V. I.
Belyi, Zh. Obshch. Khim., 1979, 49, 1522 [J. Gen. Chem.
USSR (Engl. Transl.), 1979, 49].
This work was financially supported by the President
of the Russian Federation Council for Grants (Program
for State Support of Leading Scientific Schools of the
Russian Federation, Grant NSh 3649.2014.3). The prinꢀ
cipal results were obtained using material and technical
facilities of Baikal Analytical Multiꢀaccess Center of the
Siberian Branch of the Russian Academy of Sciences.
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in revised form December 21, 2015