On the reactions of haloidmagnesiummethyl-m-carboranes with organoalkoxysilanes and chlorosilanes

Article abstract of DOI:10.1016/j.ica.2017.11.056

For the first time an effective method for the preparation of 1-methoxy(dimethyl)silylmethyl-m-carborane and 1,7-bis[chloro(dimethyl)silylmethyl]-m-carborane using 1-haloidmagnesiummethyl-m-carborane and 1,7-bis[haloidmagnesiummethyl]-m-carborane was developed. It has been established that in the course of the reaction of 1-haloidmethyl-m-carboranes with magnesium both in ether and THF, simultaneously with the formation of 1-haloidmagnesiummethyl-m-carborane – the resulting Grignard reagent, proceeds the isomerization of carborane products and their remetallization with the obtained Grignard reagent. This leads to the formation of a complex mixture of products and the decrease in the yield of the resulting Grignard reagent to 43–67%. It has been shown that by using 1-haloidmethyl-m-carboranes substituted in the second carbon atom, for example, 1,7-bis[bromomethyl]-m-carborane, in the reactions for obtaining Grignard reagents, it is possible to eliminate the isomerization of carborane products and their remetallization with the target Grignard reagent 1,7-bis[bromomagnesiummethyl]-m-carborane in 90% yield.

Full text of DOI:10.1016/j.ica.2017.11.056

Accepted Manuscript
Research paper
On the reactions of haloidmagnesiummethyl-m-carboranes with organoalkox-
ysilanes and chlorosilanes
Boris A. Izmaylov, Valerii A. Vasnev, Galy D. Markova
PII:
S0020-1693(17)30842-3
https://doi.org/10.1016/j.ica.2017.11.056
ICA 18026
DOI:
Reference:
Inorganica Chimica Acta
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Revised Date:
Accepted Date:
13 June 2017
24 November 2017
25 November 2017
Please cite this article as: B.A. Izmaylov, V.A. Vasnev, G.D. Markova, On the reactions of haloidmagnesiummethyl-
m-carboranes with organoalkoxysilanes and chlorosilanes, Inorganica Chimica Acta (2017), doi: https://doi.org/
10.1016/j.ica.2017.11.056
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On the reactions of haloidmagnesiummethyl-m-carboranes
with organoalkoxysilanes and chlorosilanes
Boris A. Izmaylov, Valerii A. Vasnev, Galy D. Markova*
A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 28
Vavilov Str., Moscow, 119991, Russia
* Corresponding author
E-mail address: mgaly@yandex.ru (G.D.Markova)
This research did not receive any specific grant from funding agencies in the public, commercial
or not-for-profit sectors.
A B S T R A C T
For the first time an effective method for the preparation of
1-methoxy(dimethyl)silylmethyl-m-carborane and
1,7-bis[chloro(dimethyl)silylmethyl]-m-carborane using 1-haloidmagnesiummethyl
-m-carborane and 1,7-bis[haloidmagnesiummethyl]-m-carborane was developed. It
has been established that in the course of the reaction of 1-haloidmethyl-m-
carboranes with magnesium both in ether and THF, simultaneously with the
formation of 1-haloidmagnesiummethyl-m-carborane - the resulting Grignard
reagent, proceeds the isomerization of carborane products and their remetallization
with the obtained Grignard reagent. This leads to the formation of a complex
mixture of products and the decrease in the yield of the resulting Grignard reagent
to 43-67%. It has been shown that by using 1-haloidmethyl-m-carboranes
1

substituted in the second carbon atom, for example, 1,7-bis[bromomethyl]-m-
carborane, in the reactions for obtaining Grignard reagents, it is possible to
eliminate the isomerization of carborane products and their remetallization with the
target Grignard reagent 1,7-bis[bromomagnesiummethyl]-m-carborane in 90%
yield.
Keywords:
Grignard
reagent;
Haloidmagnesiummethyl-m-carboranes;
Dimethyldiethoxysilane; Dimethyldichlorsilane; Remetallization.
1. Introduction
Earlier
we
obtained
mono-
and
disilylmethylcarbosubstituted
o(m)-carboranes by the reaction of mono- and dilithium-o(m)-carboranes with
chloromethyl(organo)alkoxysilanes [1,2]. In carboranemethyl containing
organosilicone compounds, the Si-CH2-Ccarb bond system possesses high thermal
stability and resistance to the action of aggressive reagents [1-10]. From
synthesized compounds were obtained carboranylmethyl(organo)siloxane and
silazane fluids, oils and lubricants [2,4-8], elastomers and vulcanizates [9],
thermosetting products for adhesives [8,10,11].
For the synthesis of carboranylmethyl containing organosilicone compounds with
Si-CH2-Ccarb bond system, the reaction of haloidmagnesiummethyl-m-carboranes
with organoalkoxysilanes and chlorosilanes is also of interest. Attention to this
2

reaction is caused by the use in it not only haloidmagnesiummethyl-m-carboranes
but also common organoalkoxysilanes and chlorosilanes, rather than
carbofunctional chloromethyl containing organoalkoxysilanes, which were used in
reactions with lithium-m-carboranes [1, 2].
2. Results and discussion
The results of investigation of the reaction of haloidmagnesiummethyl-m-
carboranes with dimethyldimethoxysilane and dimethyldichlorosilane are
represented in this paper. It was found that in a course of the reaction of
1-chloromagnesiummethyl-m-carborane with dimethyldimethoxysilane in the
solution of diethyl ether a mixture of 66% of 1-methoxy(dimethyl)silylmethyl-m-
carborane (I), 11% of 1-methyl-7-methoxy(dimethyl)silyl-m-carborane (II), 6% of
1-methoxy(dimethyl)silyl-7-methoxy(dimethyl)silylmethyl-m-carborane (III) and
17% of 1-methyl-m-carborane (IV) was formed (Scheme 1).
3

Me
CH2Si(OMe)
Me
Et2O
H
CH2MgX
+
H
+ (MeO)2SiMe2
I
Me
Me
(MeO)Si
Me
Me
Me
Si(OMe)
H
CH Si(OMe) Me
+
+
+
2
Me
Me
II
III
IV
X=Cl, Br
Scheme 1.
Reactions of 1-haloidmagnesiummethyl-m-carboranes with
dimethyldimethoxysilane in a solution of diethyl ether.
In THF 1-chloromagnesiummethyl-m-carborane reacts with
dimethyldimethoxysilane and also form the mixture consisting of 45% (I), 28%
(II), 2% (III) and 25% (IV).
In the reaction of 1-bromomagnesiummethyl-m-carborane with
dimethyldimethoxysilane both in ether and in THF, mixtures of products, that are
close in composition, are formed. So the mixture of products consisting of 35% (I),
4

31% (II), 7% (III) and 27% (IV) is formed in the ether, and in the THF - the
mixture of products consisting of 33% (I), 30% (II), 4% (III) and 33% (IV).
To facilitate the isolation of the compound (I) from the reaction mixtures, the
ability of Si-Ccarb bond in the compounds (II) and (III) to splitting under the action
of nucleophilic and electrophilic reagents was used. For this mixture of products
from
the
reactions
of
haloidmagnesiummethyl-m-carboranes
with
dimethyldimethoxysilane was treated at room temperature by catalytic amounts of
sodium methoxide in methanol solution. In the presence of sodium methoxide, the
substance (II) in the mixture is transformed into substance (IV) and substance (III)
into substance (I) (Scheme 2). Substances (I) and (IV) were isolated from the new
mixture by distillation.
II
IV
MeONa
I + II + III + IV
III
MeOH
I
Scheme 2.
The transformation of the compounds in the presence of sodium methoxide.
Substances (I) and (IV) were isolated from the new mixture by distillation. Thus,
1-methoxy(dimetyl)silylmethyl-m-carborane (I) was isolated from mixtures
obtained from 1-chloromagnesiummethyl-m-carborane in ether and THF and
treated with sodium methoxide with yield of 60% and 40%, respectively and from
mixtures based on 1-bromomagnesiummethyl-m-carborane with a yield of 30%, in
5

both solvents. The formation of silicon-containing products indicates a low
selectivity of the reaction of formation of initial Grignard reagents -
haloidmagnesiummethyl-m-carboranes both in ether and in THF.
Formation of significant amounts of by-products in these reactions is apparently
due to the fact that the reactions of the initial 1-haloidmethyl-m-carboranes with
magnesium both in ether and in THF result in isomerization of starting 1-
haloidmethyl-m-carboranes, which lead to the formation of by-products.
We suppose that 1-bromomethyl-m-carborane reacts with magnesium more
readily than 1-chloromethyl-m-carborane. Therefore, in the case of the bromo
derivative, more carborane anions apparently formed on the magnesium surface,
which increases the possibility of interaction between them and explains the
formation of more by-products than in the case of a chloroderivative product. It is
also possible that in the reaction of 1-bromomethyl-m-carborane with magnesium
in THF also takes place intermolecular reaction of remetallization of isomerization
products with the resulting Grignard reagent. The remetallization reaction is
greatly facilitated in the presence of a stronger solvating solvent [12], which is
THF compared to diethyl ether. Previously, a significant influence of the solvent
was shown on the example of formation of o-carborane methyl derivatives
[13,14,15].
It can be assumed that initially from 1-bromomethyl-m-carborane in THF forms
target Grignard reagent - 1-bromomagnesiummethyl-m-carborane (V) which
6

metallizes 1-bromomethyl-m-carborane giving 1-methyl-m-carborane and 1-
bromomagnesium-7-bromomethyl-m-carborane (VI). The latter, upon interaction
with magnesium, converts to 1-bromomagnesium-7-bromomagnesium-methyl-m-
carborane
(VII),
which
in
turn
metallizes
1-bromomethyl-m-carborane giving 1-bromomagnesium-7-methyl-m-carborane
(VIII) (Scheme3):
Mg
CH2Br
V
CH2Br
H
H
a)
THF
BrMg
CH2Br
Me
CH2Br
+
H
H
V
b)
+
VI
Mg
BrMg
CH2MgBr
VII
VI
c)
CH2Br
H
BrMg
Me
d)
VII +
VIII
Scheme 3.
Isomerization of carboranemagnesiumorganic compounds.
It is obvious that similarly in reactions of the types b), c) and d) (Scheme 3)
take place the formation of isomerized products by the interaction of 1-
7

bromomethyl-m-carborane with magnesium in diethyl ether, as well as in the
reactions of chloromethyl-m-carboranes with magnesium diethyl ether and THF.
The reaction with bromine at which 1-methyl-7-bromo-m-carborane, 1-
bromomethyl-m-carborane and 1-bromomethyl-7-bromo-m-carborane are formed
from compounds (V) – (VIII) is a simple and precise determination of the relative
amounts of the reaction products of interaction 1-haloidmethyl-m-carboranes with
magnesium (Scheme 4):
Br2
CH2MgX
CH2Br
H
H
Br2
XMg
Me
Br
Me
Br2
CH2Br
Br
XMg
CH2MgX
Scheme 4.
Bromation of carboranemagnesiumorganic compounds.
.
8

These compounds and 1-methyl-m-carborane are easily determined by gas-liquid
chromatography.
It was found that the relative amounts of compounds (V-VIII) and 1-methyl-m-
carborane vary depending on the reaction conditions: the amounts of magnesium
and ether (or THF) and the rate of addition 1-bromomethyl-m-carborane to
magnesium.
In present work, as a rule, the reaction was carried out at a molar ratio of
1-bromomethyl-m-carborane : magnesium, equal to 1:2. The following ratio of
reaction products was found: in ether - 36% (V), 32% (VI), 8% (VII) and 24% of
1-methyl-m-carborane; in THF - 34% (V), 31% (VI), 4% (VII) and 31% of
1-methyl-m-carborane. With a decrease in the amount of magnesium to the ratio
1-haloidmethyl-m-carborane : magnesium = 1:1, the amounts of compound VIII
and 1-methyl-m-carborane increase. The amount of 1-methyl-m-carborane
determined by this method corresponds to the amount of 1-methyl-m-carborane
which sublimated in vacuum from the reaction mass after removal of ether or THF
We supposed that the use of 1-haloidmethyl-m-carboranes substituted at the
second carbon atom, for example 1-haloidmethyl-7-methyl-m-carborane or
1,7-bis(haloidmethyl)-m-carborane, in the reactions for obtaining Grignard
reagents, will allow to eliminate the isomerization of carborane products and the
reaction of their remetallization and, as a result, increase the yield of Grignard
reagent. Indeed, it has been found that the reaction of 1,7-bis(bromomethyl)-m-
9

carborane
with
magnesium
in
diethyl
ether
produces
only
1,7-bis(bromomagnesiummethyl)-m-carborane in 90% yield. Grignard reagents of
this type, reacting with dimethyldimethoxysilane or dimethyldichlorosilane
(Scheme 5), form the corresponding 1,7-bis[methoxy(dimethyl)silylmethyl]-m-
carborane (IX) and 1,7-bis[chloro(dimethyl)silylmethyl]-m-carborane (X) in 80%
yield:
Me
Me
Et2O
BrMgCH2
CH MgBr
2
XSiCH2
Me
CH2SiX
Me
+
Me2SiX2
IX, X
X = OMe (IX), Cl (X)
Scheme 5.
Reaction of bis-Grignard reagents of m-carborane with
dimethyldimethoxysilane or dimethyldichlorosilane.
3. Conclusions
Thus, as a result of investigations, it has been found that in the course of the
reaction 1-haloidmethyl-m-carboranes with magnesium both in ether and THF
simultaneously with the formation of 1-haloidmagnesiummethyl-m-carborane - the
10

target Grignard reagent, goes the isomerization of carborane products and their
remetallization with the resulting Grignard reagent. This leads to the formation of
complex mixture of products and the decrease in the yield of the target Grignard
reagent to 35-68%.
It has been found that using 1-haloidmethyl-m-carboranes substituted at the
second carbon atom, for example 1,7-bis(bromomethyl)-m-carborane, in the
reactions of obtaining Grignard reagents, it is possible to eliminate the carborane
products isomerization and their remetallization with the resulting Grignard
reagent and obtain target Grignard reagent - 1,7-bis(bromomagnesiummethyl)-m-
carborane in ether with 90% yield. It has been shown the possibility of obtaining
from Grignard reagent of this type and dimethyldimethoxysilane and also
dimethyldichlorosilane, respectively, 1,7-bis[methoxy(dimethyl)silylmethyl]-m-
carborane (IX) and 1,7-bis [chloro(dimethyl)silylmethyl]-m-carborane (X) in 80%
yield.
4. Experimental
4.1. Materials and methods
For syntheses were used: 1-chloromethyl-m-carborane, m.p. = 91-92 ° C (from
hexane); 1-bromomethyl-m-carborane, m.p. = 31-320C (from hexane);
1,7-bis (bromomethyl)-m-carborane, b.p. = 1410C (2.7 gPa);
dimethyldimethoxysilane, b.p. = 800C, nd20 = 1.3708; dimethyldichlorosilane; b.p.
= 70-710C, nd20 = 1.4002. All reactions with carborane derivatives were carried out
11

in an atmosphere of dry nitrogen. Diethyl ether and THF were absolutized by
distillation over LiAlH4. The molecular weights of compounds (I), (IX) and (X)
were determined by cryoscopy in benzene. GLC was carried out on 2 m long
columns, filled with 10% silicone elastomer "E-301" on a chromaton in
temperature range 150-1800C (gas-carrier is helium). NMR spectra in CDCl3 were
recorded using Bruker Avance-400 spectrometer with 400.13 MHz working
frequency. IR spectra were recorded using "Specord M80" infrared
spectrophotometer (Germany) in the frequency range 4000-400 cm-1 on KBr
plates.
4.2. Reaction of 1-chloromethyl- and 1-bromomethyl-m-carboranes with
magnesium in diethyl ether
1.4 g of magnesium filings under a 50 ml layer of absolute diethyl ether was
activated by several drops of 1,2-dibromoethane and 7.7 g (0.039 mol) of
1-chloromethyl-m-carborane in 50 ml of absolute diethyl ether was then added.
The mixture was refluxed for 1 h. The completion of the reaction was determined
by GLC method after hydrolysis of the sample from the reaction mixture. Then the
solution of 1-chloromagnesiummethyl-m-carborane was filtered off from the
magnesium excess and introduced into the reaction. An aliquot part of this solution
was added with stirring at -300C to a solution of dry Br2 taken with 50% excess in
hexane distilled over LiAlH4. Then solvent with excess of Br2 was removed in
12

vacuum. The residue, according to GLC, consisted of 17% of 1-methyl-m-
carborane, 11.7% of 1-bromo-7-methyl-m-carborane, 67% of 1-bromomethyl-m-
carborane and 4% of 1-bromo-7-bromomethyl-m-carborane.
Similarly, the reaction of 1-bromomethyl-m-carborane with magnesium in
diethyl ether was carried out. An aliquot part of the Grignard reagent was treated
with Br2 in hexane to obtain a product mixture which, according to GLC, consisted
of: 25% 1-methyl-m-carborane (IV), 36% 1-bromomethyl-m-carborane (V), 33%
1-bromo-7-methyl-m-carborane (VIII) and 6% 1-bromo-7-bromomethyl-m-
carborane (VI) (see Scheme 3).
4.3. Reactionm of 1-bromomethyl-m-carborane with magnesium in THF
The reaction of 1-bromomethyl-m-carborane with magnesium in THF was carried
out similarly, as in diethyl ether. After treatment of aliquot part of the Grignard
reagent with Br2 in hexane, a mixture of products which consisted, according to
GLC, of 33% 1-methyl-m-carborane (IV), 31% 1-methyl-7-bromo-m-carborane
(VIII), 34 % 1-bromomethyl-m-carborane (V) and 2% 1-bromo-7-bromomethyl-
m-carborane (VI) was obtained (see Scheme 3).
4.4. Reaction of 1,7-bis(bromomethyl)-m-carborane with magnesium in diethyl
ether
13

2.8 g of magnesium filings under a 100 ml layer of absolute diethyl ether was
activated by several drops of 1,2-dibromoethane and 6.6 g (0.02 mol) of 1,7-
bis(bromomethyl)-m-carborane in 50 ml of absolute diethyl ether was then added.
The mixture was refluxed for 1 h. The completion of the reaction was determined
by GLC method after hydrolysis of the sample from the reaction mixture. Then the
solution of 1,7-bis(bromomagnesium)-m-carborane was filtered off from the
magnesium excess and introduced into the reaction. An aliquot part of Grignard
reagent was treated with Br2 in hexane and a mixture of products was obtained
which contained, according to GLC, 90% of 1,7-bis(bromomethyl)-m-carborane.
4.5. Reactions of 1-chloromagnesiummethyl- and 1-bromomagnesiummethyl-m-
carboranes with dimethyldimethoxysilane in diethyl ether
10.85 g (0.05 mol) of 1-chloromagnesiummethyl-m-carborane in 70 ml of absolute
diethyl ether was added dropwise with stirring to 12 g (0.1 mol) of
dimethyldimethoxysilane in 70 ml of absolute diethyl ether. The mixture was
refluxed for 3 h and cooled. Then 3 ml of 1% sodium methoxide solution in
methanol was added, the mixture was refluxed with stirring for 3 h, ether and an
excess of dimethyldimethoxysilane were distilled off on a rotary evaporator, and
12.3 g of the mixture was obtained. 1-methyl-m-carborane (IV) was distilled from
mixture in vacuum and 7.4 g (60%) of 1-methoxy(dimethyl)silylmethyl-m-
carborane (I) was obtained in the residue. B.p.= 115-1170C (133 Pа), m.p.= 120-
14

1210C (from hexane), nD = 1.5160. Found (%): C, 29.70; H, 9.11; B, 44.0; Si,
20
11.80. Mn 245. For C6H22SiB10O requires (%): С, 29.24; H, 8.99; B, 43.86; Si,
11.40. Mn=246. IR ( ʎ, сm-1): 2600 (B-H), 2980 and 2900 (Si-CH2). 1Н NMR
(CDCl3, ppm): 0.27 (6H, s,2CH3), 1.70 (2H, s CH2), 3.00 (1H, s, CHcarb.), 3.55
(3H, s, OCH3).
4.6. Reaction 1-chloromagnesiummethyl-m-carborane with dimethyldimethoxy-
silane in THF
The reaction was carried out similarly to mode 3.3. From 10.5 g (0.05 mol) of
Grignard reagent and 12 g (0.1 mol) of dimethyldimethoxysilane 4.9 g (40%) of
compound (I) was obtained.
4.7. Reaction of 1-bromomagnesiummethyl-m-carborane with
dimethyldimethoxysilane in diethyl ether and THF
The reaction of 1-bromomagnesiummethyl-m-carborane with
dimethyldimethoxysilane in diethyl ether and THF was carried out similarly to
mode 3.3. From 13 g (0.05 mol) of Grignard reagent and 12 g (0.1 mol) of
dimethyldimethoxysilane both in diethyl ether and THF 3.7 g (30%) of compoud I
was obtained.
4.8. Reaction of 1,7-bis(bromomagnesiummethyl)-m-carborane with
dimethyldimethoxysilane
15

9.5 g (0.025 mol) of 1,7-bis(bromomagnesiummethyl)-m-carborane in 70 ml of
absolute diethyl ether was added dropwise with stirring to 12 g (0.1 mol) of
dimethyldimethoxysilane in 70 ml of absolute diethyl ether. The mixture was
refluxed for 3 h and cooled. The mixture was refluxed for 5 h. Diethyl ether and
an excess of dimethyldimethoxysilane were distilled off on a rotary evaporator and
8.8 g of mixture was obtained. Then volatile products were distilled off in vacuum
and 7 g (80%) of 1,7-bis[methoxy(dimethyl)silylmethyl]-m-carborane (IX) was
obtained. B.p.= 168-1700C (133 Pа), nD20 = 1.5105. Found (%): C, 35.00; H, 9.18;
B, 31.90; Si, 16.31. Mn=346. For C10H32Si2B10O2 requires (%): C, 34.45; H, 9.25;
B, 31.0; Si, 16.11. Mn=348. IR ( ʎ, сm-1): 2600 (B-H), 2980 and 2900 (Si-CH2).
1Н NMR (CDCl3, ppm): 0.32 (12H, s, 4CH3), 1.70 (4H, s, 2CH2), 3.59 (6H, s,
2OCH3).
4.9. Reaction of 1,7-bis(bromomagnesiummethyl)-m-carborane with
dimethyldichlorosilane
The reaction of dimethyldichlorosilane (12.9 g, 0.1 mol) with 1,7-
bis(bromomagnesiummethyl)-m-carborane (9.5 г, 0.025 mol) was carried out
similarly to mode 3.7. Yield of compound (X) is 80%. B.p.= 152-154 (133 Pа),
20
nD =1.534. Found (%): C, 27.20; H, 7.28; Si, 15.20; B, 29.20; Сl, 19.18. Mn=355.
For C8H26Si2B10Cl2 requires (%): C, 26.27; H, 7.33; Si, 15.71; B, 30.23; Cl, 19.85.
16

Mn=357. IR ( ʎ, сm-1): 2600 (B-H), 2980 and 2900 (Si-CH2). 1Н NMR (CDCl3,
ppm): 0.48 (12H, s, 4CH3), 1.30 (4H, s, 2CH2).
4.10. Preparation of starting haloidmethyl-m-carboranes
1-Chloromethyl-m-carborane (XI) and 1-bromomethyl-m-carborane (XII) can, t be
obtained by thermal isomerization of the corresponding 1-haloidmethyl-o-
carboranes, since the migration of the halogen atom to the boron atoms of
carborane nucleus occurs upon heating [16]. Their synthesis was carried out in the
following way. In the reaction of paraform with 1-lithium-m-carborane, which was
prepared by metallization of m-carborane with butyl lithium at a ratio of 1:1 in
ether, a mixture of 1-hydroxymethyl- (XIII) and 1,7-dioxymethyl-m-carborane
(XIV) in ratio of 1:1 was obtained (Scheme 6).
1. C4H9Li
H
CH OH
2
HOCH
CH2OH
H
+
H
2
2. CH2O
3. H+
XIII
XIV
Scheme 6.
Preparation of mixture of 1-oxymethyl- and 1,7-dioxymethyl-m-carborane in
the ratio 1:1 in the process of metallization of m-carborane with butyllithium.
4.10.1. Preparation of 1-oxymethyl-m-carborane (XIII)
17

To a solution of lithium-m-carborane (from 10 g of m-carborane and 0.007 mol
of C4H9Li) in a mixture of 30 ml of ether and 50 ml of benzene, 3 g of paraform
were added in small portions with stirring. The mixture was refluxed for 2 h. After
usual treatment the reaction product was chromatographed on a column with Al2O3
(eluent – chloroform) to give 4.2 g (35%) of 1-oxymethyl-m-carborane (XIII) with
m.p. = 214-215OC (from hexane). Found, (%): C, 20.68; H 7.83; B 61.48. For
С3H14B10O, requires, %: С: C 20.68; H 8.10; B 62.04. Then column was washed
with methanol to give 4.3 g (30%) of 1,7-bis(oxymethyl)-m-carborane (XIV), m.p.
= 193-195OC (from toluene). According to the literary data [3] m. p. = 194-196OC.
It turned out that compound (XIII), unlike 1-hydroxymethyl-o-carborane [17]
and primary alcohols, reacts with PCl5 to form substance (XI) and m-
carboranylmethyl ester of phosphoric acid (XV):
CH2O)3PO
H
CH Cl
2
+ PCl
(H
4 XIII
+
+ 4HCl
5
XV
XI
Scheme 7.
Reaction of 1-oxymethyl-m-carborane with PCl5.
The chloro-derivative (XI) is not formed from the alcohol (XIII) under the action
of SOCl2 in the presence or absence of pyridine. Under the action of PBr5 on
18

alcohols (XIII) and (XIV) there is no exchange of OH groups with a bromine atom
but phosphoric esters are formed. Compound (XII) was obtained from alcohol
(XIII) by the action of (C6H5)3PBr2 (Scheme 8):
CH2OH
H
CH2Br
+
(C H ) PBr
2
H
+
+
(C H ) PO HBr
6
6
5 3
5 3
XII
XIII
Scheme 8.
Synthesis of 1-bromomethyl-m-carborane.
Similarly, from the alcohol (XIV) was obtained 1,7-bis(bromomethyl)-m-
carborane (XVI) (Scheme 9):
CH2OH
BrCH2
CH2Br
2(C H ) PO+
+
2HBr
(C H ) PBr
2
+
HOCH2
6
5 3
6
5 3
XVI
XIV
Scheme 9.
Synthesis of 1,7-bis(bromomethyl)-m-carborane.
4.10.2. Preparation of 1-chloromethyl-m-carborane (XI) [18]
19

To 9.5 g of PCl3 in 3 ml of absolute benzene was added with stirring a solution of 5
g of 1-hydroxymethyl-m-carborane in 25 ml of absolute benzene. The mixture was
boiled until HCl removal stopped (2 h), treated with water, extracted with ether and
then ether was distilled off. The obtained residue was chromatographed on a
column with Al2O3 (eluent-petroleum ether with b.p. = 40-70OC) and 1.25 g (92%)
of product (XI) was obtained, m.p. = 91-92OC (from hexane). Found (%): C,
18.82; H 6.48; B 56.32. For С3H13B10Cl, requires, %: С: C 18.70; H 6.80; B 56.11.
Then column was washed with chloroform to give 3.65 g (90%) of m-
carboranylmethyl ester of phosphoric acid (XV), m.p. = 246-247OC (from hexane).
Found (%): С 19.27; H 7.05; B 57.5; P 5.63. For С9H39B30O4P, requires, %: C
19.07; H 6.94; B 57.29; P 5.46.
4.10.3. Preparation of 1-bromomethyl-m-carborame (XII) [18]
The solution of 1.45 g of Br2 in 5 ml of absolute benzene was added to a solution
of 1.0 g of 1-hydroxymethyl-m-carborane and 2.1 g of P(C6P5)3 in 15 ml of
absolute benzene at room temperature with stirring. The mixture was refluxed for 2
h, washed with water, dried over Na2SO4 and solvent was distilled off. The
obtained residue was chromatographed on a column with Al2O3 (eluent-petroleum
ether with b.p. = 40-70OC) and 1.3 g (95%) of product (XII) was obtained, m.p. =
31-32OC (from hexane). Found (%): С 15.19; H 5.92; B 32.63. For С3H13B10Br2,,
requires, %: C 14.55; H 4.27; B 32.75.
20

4.10.4. Preparation of 1,7-(dibromomethyl)-m-carborane (XVI) [18]
1,7- (dibromomethyl)-m-carborane (XVI) was prepared similarly to mode 3.10.2
from 3.75 g of 1,7-dioxymethyl-m-carborane (XIV) [19], 12.6 g of P(C6P5) and 8.7
g of Br2 in 100 ml of absolute benzene. Yield of product (XIV): 5.3 g (87.5%), b.p.
= 141OC (2.7 gPa). Found,% C 14.93; H, 4.32; Br, 32.75. Calculated for
C4H14B10Br2, %: C, 14.55; H, 4.27; B, 32.75.
References
21

[1] V.N. Каlinin, B.А. Izmaylov, А.А. Каzantzev, L.I. Zakharkin,
K.A. Andriyanov, Dokl. Acad. Sci. USSR., 246 (1979) pp. 616-620.
[2] V.N. Каlinin, B.А. Izmaylov, А.А. Каzantzev, V.D. Myakushev,
А.А. Zhdanov, L.I. Zakharkin, J. Organomet. Chem., 216 (1981), pp. 295-
320.
[3] R.N. Grimes, Carboranes, Acadimic Press. 3rd-ed., (2016), pp.1058.
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Bull. Int. Ed., 65(10) (2014) pp. 1-5.
22

[12] L.I. Zakharkin, O.Ju. Okhlobystin, K.A. Bilevitch, Tetrahedron., 21 (1965)
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[13] A.R.Popescu, A.D. Musteti, A. Ferrer-Ugalde, C.Vinas, R.Nunez, F.
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[15] C.Vinas, R. Benakki, F. Teixidor, J. Casabo, Inorg. Chem., 34(14)
(1995) pp.3844-3845.
[16] L.I. Zakharkin, V.N. Каlinin, G.G. Gigareva, А.V.Grebennikov, Bull. Acad.
Sci. USSR, Div.Chem., (1968). pp.1862-1865.
[17] L.I. Zakharkin, V.А.Bratzev, Yu.А. Chipovskii, J. Gen. Chem. USSR., 35
(1965) pp. 2160-2167.
[18] L.I. Zakharkin, A.I. Kovredov, А.А. Каzantzev, M.G. Meiramov, J. Gen.
Chem. USSR., 51(2) (1981) pp.357-361.
[19] D.Grafsyein, J.Dvorak, Inorg. Chem. 2 (1963) pp. 1128-1133.
23

Novel method for the preparation of silylmethyl derivatives of m-carboranes was developed
24

Me
CH2Si(OMe)
Me
H
CH2MgX
+ (MeO)2SiMe2
H
X=Cl, Br
25