The Isocyanide-Induced Formation of Dicyclopentadienyltantalum Monoalkyl Species from Hydride Olefin Complexes

Reaction of endo Cp2Ta(H)L (L = C3H6, C4H8 (1-butene)) with aryl- and alkyl-isocyanides R´NC (R´ = 2,6-(CH3)2C6H3, cyclo-C6H11, CH3 and t-C4H9) gives the thermally stable isocyanide adducts of Cp2TaR (R = C3H7, C4H9). The extraordinarily strong metal—isocyanide interaction leads to a non-linear “carbene-like” structure for these complexes and gives rise to the possibility of reactions at the nitrogen lone-pair electrons. The tantalocene isocyanide complexes react with Lewis acids, such as AlEt3 to give 1/1 adducts Cp2TaR • R´NC : AlEt3