On the properties of binuclear cyclopentadienyl-fulvalene-nitrene complexes of Nb

Abstract The properties of (η 5 :η 5 -C 5 H 4 C 5 H 4 )(C 5 H 5 ) 2 Nb 2 (μ-NC 6 H 5 ) 2 (I) have been investigated. Reaction of I with acids (HCl, H 2 SO 4 and CX 3 COOH) includes diprotonation to form the dication, [(η 5 :η 5 -C 5 H 4 C 5 H 4 )(C 5 H 5 ) 2 Nb 2 − (μ-NC 6 H 5 ) 2 H 2 ] 2+ (II). The process is reversible and the initial neutral compound I may be recovered under the action of a base. The protonated compound II may lose NC 6 H 5 ligands as C 6 H 5 NH 3 + ; the paramagnetic product of the dissociation (C 5 H 4 C 5 H 4 )(C 5 H 5 ) 2 Nb 2 Cl 4 (III) has been isolated.