Unusual κ1 coordination of a β-diketiminate ligand in niobium complexes

Abstract

Reaction of (BDI)Nb(N^tBu)Cl₂py with NaCp results in the κ¹-coordination of the BDI ligand in the complex (κ¹-N,BDI)CpNb(N^tBu)Cl (2). Via chloride abstraction from 2, we develop synthetic routes to structurally analogous cationic and Nb^IV pseudo-four coordinate complexes where the BDI ligand returns to the κ²-coordination mode. We compare these to our previously reported tetrahedral niobium bis(imido) complexes to investigate the effects of the Cp ligand on the properties of Nb-BDI-imido systems. Substitution of the chloride in 2 with a hydride also causes return to bidentate binding of the BDI ligand. The X-ray crystal structures of these complexes have been determined, and the structural parameters reflecting the consequences of the electronic differences are discussed.