Oxidation of substituted benzyl amines using a phenoxo-bridged dimeric nickel(II) complex: synthesis, crystal structure and catalytic activity

A benzimidazole-based Schiff base ligand and its dinuclear complex [Ni-2(L)(2)(NO3)(2)] where L = 2-[2-(1H-benzo[d]imidazole-2-yl)ethylimino)methyl] phenol have been synthesized. An X-ray crystallographic study showed that both the metal centers in the complex adopt a distorted octahedral geometry. Variable-temperature magnetic studies suggest that the nickel(II) centers are antiferromagnetically coupled. Cyclic voltammetry confirms that the dinickel complex retains its identity in the presence of tert-butyl hydroperoxide in the solution state. The complex has been used as a catalyst for the homogeneous oxidation of substituted benzyl amines in the presence of tert-butyl hydroperoxide. The yields of these reactions depend upon the nature of the substituent in the aromatic ring.