A bis(silyl)nickel complex containing an o-carboranylene and its application in facile double silylation of alkynes and alkenes

The reaction of 1,2-bis(dimethylsilyl)carborane (1) with Ni(PEt3)(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-B10H10C2(SiMe2)(2)(RC=CR') (R = R'= Ph (3); R = Ph, R'= H (4); R = R'= Pt (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.