TANTALUM-BOROLLIDE ALKYL COMPLEXES

Reaction of Me(3)TaCl(2) with Li-2[C4H4BN(CHMe(2))(2)] (THF) produces [eta(5)-C4H4BN(CHMe(2))(2)]Me(2)Ta[mu-eta(5)-C4H4BN(CHMe(2))(2)]TaMe(4) (1) which is an extremely deficient (24 electron) triple decker complex. Similarly, mononuclear [eta(5)-C4H4BN(CHMe(2))(2)]TaMe(3)(PMe(3)) (2) is obtained when Me(3)TaCl(2)(PMe(3)) is used as the metal source. Compound 2 undergoes clean migratory insertion chemistry with 2,6-dimethylisocyanide. The product of the reaction of 2 with three equivalents of isocyanide is the metallabicyclic complex [eta(5)-C4H4BN(CHMe(2))(2)]Ta[eta(2)-MeCN(2,6-Me(2)-C6H3)][eta(3)-(2,6-Me(2)C(6)H(3))NCHCH2C(Me)N(2,6-Me(2)-C6H3)] which has been structurally characterized.