A Bis(silyl)nickel Complex Containing an o-Carboranylene and Its Application in Facile Double Silylation of Alkynes and Alkenes

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The reaction of 1,2-bis(dimethylsilyl)carborane ( 1 ) with Ni(PEt 3 ) 4 yielded the cyclic bis(silyl)nickel complex ( 2 ). 2 was found to be a good catalyst for the double silylation reaction of alkynes and alkenes. Thus, the reaction of 1 with RC⋮CR‘ in the presence of a catalytic amount of 2 afforded the six-membered disilylene ring compounds o -B 10 H 10 C 2 (SiMe 2 ) 2 (RC CR‘) (R = R‘ = Ph ( 3 ); R = Ph, R‘ = H ( 4 ); R = R‘ = Et ( 5 ); R = Ph, R‘ = Me ( 6 ); R = R‘ = Me ( 7 )). In contrast, the reaction of 1-phenyl-2-(trimethylsilyl)acetylene with 1 in the presence of a catalytic amount of 2 afforded the six-membered disilylene ring compound ( 9 ) and the five-membered disilylene ring compound ( 10 ). The stoichiometric reaction of 2 with an active alkyne such as dimethyl acetylenedicarboxylate gave the six-membered disilylene ring compound ( 11 ). The intermedate 2 also was found to be a good catalyst for the double silylation of some alkenes. Thus, the reaction of 1 with 4-vinylanisole in the presence of a catalytic amount of 2 afforded the five-membered disilylene ring compound ( 15 ). However, treatment of 1 with 1,1-diphenylethylene under the same reaction conditions yielded a different type of five-membered disilylene ring compound ( 17 ). The reaction of 1 with 2,3-dimethylbutadiene in the presence of the nickel catalyst also was studied. The crystal structures of 2, 9, and 14 are described.