Synthesis of cationic niobocene imido derivatives

Abstract

Following from our previous work in the synthesis and reactivity of niobium imido complexes,1 we have studied the preparation of cationic derivatives. The reduction of [Nb(=NPh)(eta5-C5H4SiMe3)2Cl] gives the short-lived niobocene(IV) radical [Nb(=NPh)(eta5-C5H4SiMe3)2. which was rapidly oxidized to the niobocene(V) cationic species [Nb(=NPh)(eta5-C5H4SiMe3)2(L)]+ (L = CO, ButNC) by the reaction with [Fe(eta5-C5H5)2][BPh4]. In a similar manner, the ansa-niobocene compound [Nb(=NBut){Me2Si(eta5-C5Me4)(eta5-C5H4)}(ButNC)][BPh4] was synthesized. However, in the attempted reduction of [Nb(=NBut){Me2Si(eta5-C5H4)2}Cl], the expected radical species was not observed. Instead the niobocene (V) imido dimer product was identified. The reaction with H2 and I2 gave [Nb(=NBut){Me2Si(eta5-C5H4)2}H] and [Nb(=NBut){Me2Si(eta5-C5H4)2}I], respectively.