THE CHEMISTRY OF HYDRIDE, HALIDE AND ALKYL NIOBOCENE COMPLEXES WITH COORDINATED DIAZOALKANES

The complexes Cp(2)Nb(H)(eta(1)-NNCPhAr)(Ar=Ph (1) or o-C6H4Br (2)) we re found to undergo easy substitution of a hydride ligand for a haloge n atom by the reaction of 1 with various alkylhalides with high yields of Cp(2)Nb(X)(eta(1)-NNCPh(2)) (X=Cl (4), Br (5) or I (6), Cp(2)Nb(Br )(eta(1)-NNC(Ph)-o-C6H4Br) (7) and 5 were found to be formed in a halo gen exchange reaction, and also by the thermolysis of 2. Halide diazoa lkane niobocene complexes clearly exhibit marked polarity of the metal centre. Nucleophilic substitution of bromine in 5 yielded Cp(2)Nb(Me) (eta(1)-NNCPh(2)) (8). The results of X-ray analysis of 7 are provided .