The chemistry of hydride, halide and alkyl niobocene complexes with coordinated diazoalkanes

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