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The mercuration of ortho- and meta-carboranes
249
Journalof OrganometallicChemistry, 112 (1976) 249-251 @ Ekevier Sequoia S-A., Lausanne - Printed in The Netherlands
OF ortho-
THE MERCURATION
V.L BREGADZE Institute of (U.S.S.R.) (Received
l, V.TS.
Organo-Element
January
26th,
AND
&eta-CARBORANES
KAMPEL and N.N. GODOVIKOV Compounds,
Academy
of
Sciences
of
ths
U.S.S.R.,
Moscow
1976)
Summary The mercuration of o&ho- and mefa-carboranes is described_ This mercuration proceeds at the boron atom of the icosahedral at position 9.
The reaction of direct mercuration of o- and m-carboranes has not been de_ scribed until now. We have found that such mercuration did not occur even with boiling of o-carborane with mercury acetate for several hours. This may be explained by the electron-deficient properties of the carborane nucleus which hinder electrophilic substitution reactions. We used a strong mercuration agent, mercury trifluoroacetate [l], to accom-
plish the mercuration of carborane. The interaction of carborane with one eqkvalent of mercury trifluoroacetate in trifluoroacetic acid proceeds easily at room temperature with a marked exothermic effect to give the mono-substituted product: m(o)-CHBloHl&H
+ (CF,CO,)zHg
+ CF&OzHg-m(o)-CHBloH&H
o-Carborane reacts much faster than m-carborane. This fact confirms the con-
clusion that ocarborane is attacked by electrophilic agents to a greater extent than m-carborane [2]. Treatment of carboranyltrifluoroacetates in acetone with an aqueous soIution of sodium chloride has led to the corresponding chlorides: CF3C02Hg-m(o)-CHEil,-,H&H =
C1Hg-m(o)-CHE3,0H&H
The substitution of o- and m-carboranes proceeds at position 9 of the carborane nucleus. The position of substitution was determined by bromination of carboranylmercury chlorides in carbon tetrachloride to give the known bromides: 9-ClHg-m(o)-CHB,,H,CH
2
9-Br-m(c)-CHB,0H,CH
Table 1 contains physical data of the compounds obtained.
1
b
263-264 266-267
1oH9 CH
9.ClH@o-HCB
9-ClI$-m-HCBt OHgCH
* 2.94 (2.02)
6.67 (6.33)
92
28,20 (2&52)
28,47 (26,GZ)
2.99 (2.92)
7.08 (6.33)
RO
23,08 (23.67)
2,64 (2.42)
10.31 (10.63.)
71
22.91 (Z&67)
B
2.32 (2.42)
H
(%)
10.42 (10.61)
C
Annlysls Found (c&d,)
66
(96)
Yield
COMPOUNDS
b Crystallized from tnluonc,
b
1177118
9-CF3CO2Hpm-HCB~gHgCH
0 Crystallized from tohcne/hoxnno.
a
160-162
9-CF3C02Hg-o.HCBloHgCH
n
M,P. (“C)
CARBORAiIYLMERCURY
Compounds
BORON-SUBSTITUTED
TABtP
9,63 (9834)
9,26 (9,34)
CI
62.iO (62.87)
62.01 (62.07)
(43.90)
43.36 (43.90)
Hg
:
;.,
,.
‘,
,“. ,,.
,,’
‘.
”
‘.
” ”
”;
;
”
,:
‘.., .;.,’ .
,,, ..,. ;.
1
., ,‘:,:
‘, , .’ ,,( ,” ‘, : ;. : 8.,,‘. .I,’ ‘.‘: ,, ‘, ‘, ,. .,
8’
/.
.“.
‘.
‘.
,‘, ,, ,,;m,,,
.,
“,
,,‘,
., .’ ,.
,;,
,,
‘379 ;(‘,
,379
‘.
m/c
,.
251
Refeiences. 1 H.C. Brow? and R-A. Wirkkala. J. Amer. Chem. SOC.. 88 (1966) 1447. 2 R-N. G-es. Carboranes Academic Press, New Yorkfiondon, 1970. p. 173.
Journalof OrganometallicChemistry, 112 (1976) 249-251 @ Ekevier Sequoia S-A., Lausanne - Printed in The Netherlands
OF ortho-
THE MERCURATION
V.L BREGADZE Institute of (U.S.S.R.) (Received
l, V.TS.
Organo-Element
January
26th,
AND
&eta-CARBORANES
KAMPEL and N.N. GODOVIKOV Compounds,
Academy
of
Sciences
of
ths
U.S.S.R.,
Moscow
1976)
Summary The mercuration of o&ho- and mefa-carboranes is described_ This mercuration proceeds at the boron atom of the icosahedral at position 9.
The reaction of direct mercuration of o- and m-carboranes has not been de_ scribed until now. We have found that such mercuration did not occur even with boiling of o-carborane with mercury acetate for several hours. This may be explained by the electron-deficient properties of the carborane nucleus which hinder electrophilic substitution reactions. We used a strong mercuration agent, mercury trifluoroacetate [l], to accom-
plish the mercuration of carborane. The interaction of carborane with one eqkvalent of mercury trifluoroacetate in trifluoroacetic acid proceeds easily at room temperature with a marked exothermic effect to give the mono-substituted product: m(o)-CHBloHl&H
+ (CF,CO,)zHg
+ CF&OzHg-m(o)-CHBloH&H
o-Carborane reacts much faster than m-carborane. This fact confirms the con-
clusion that ocarborane is attacked by electrophilic agents to a greater extent than m-carborane [2]. Treatment of carboranyltrifluoroacetates in acetone with an aqueous soIution of sodium chloride has led to the corresponding chlorides: CF3C02Hg-m(o)-CHEil,-,H&H =
C1Hg-m(o)-CHE3,0H&H
The substitution of o- and m-carboranes proceeds at position 9 of the carborane nucleus. The position of substitution was determined by bromination of carboranylmercury chlorides in carbon tetrachloride to give the known bromides: 9-ClHg-m(o)-CHB,,H,CH
2
9-Br-m(c)-CHB,0H,CH
Table 1 contains physical data of the compounds obtained.
1
b
263-264 266-267
1oH9 CH
9.ClH@o-HCB
9-ClI$-m-HCBt OHgCH
* 2.94 (2.02)
6.67 (6.33)
92
28,20 (2&52)
28,47 (26,GZ)
2.99 (2.92)
7.08 (6.33)
RO
23,08 (23.67)
2,64 (2.42)
10.31 (10.63.)
71
22.91 (Z&67)
B
2.32 (2.42)
H
(%)
10.42 (10.61)
C
Annlysls Found (c&d,)
66
(96)
Yield
COMPOUNDS
b Crystallized from tnluonc,
b
1177118
9-CF3CO2Hpm-HCB~gHgCH
0 Crystallized from tohcne/hoxnno.
a
160-162
9-CF3C02Hg-o.HCBloHgCH
n
M,P. (“C)
CARBORAiIYLMERCURY
Compounds
BORON-SUBSTITUTED
TABtP
9,63 (9834)
9,26 (9,34)
CI
62.iO (62.87)
62.01 (62.07)
(43.90)
43.36 (43.90)
Hg
:
;.,
,.
‘,
,“. ,,.
,,’
‘.
”
‘.
” ”
”;
;
”
,:
‘.., .;.,’ .
,,, ..,. ;.
1
., ,‘:,:
‘, , .’ ,,( ,” ‘, : ;. : 8.,,‘. .I,’ ‘.‘: ,, ‘, ‘, ,. .,
8’
/.
.“.
‘.
‘.
,‘, ,, ,,;m,,,
.,
“,
,,‘,
., .’ ,.
,;,
,,
‘379 ;(‘,
,379
‘.
m/c
,.
251
Refeiences. 1 H.C. Brow? and R-A. Wirkkala. J. Amer. Chem. SOC.. 88 (1966) 1447. 2 R-N. G-es. Carboranes Academic Press, New Yorkfiondon, 1970. p. 173.