Abstract

The synthesis of trans-[Ni(dbm)2(RN=C(Me)- NHR)2] (dbm = 1,3-diphenylpropanedionate; R = phenyl, p-tolyl, 3,5-dimethylphenyl, 3,5-dichlorophenyl) has been achieved by reaction of [Ni(dbm) <inf>2</inf>(H <inf>2</inf>O) <inf>2</inf>] with two equivalents of the amidine ligands, RN=C(Me)NHR. X-ray crystallographic studies reveal that trans-[Ni(dbm)2- (RN=C(Me)NHR)2] (R = 3,5-dimethylphenyl) exhibits an intramolecular N-H⋯O hydrogen bond, which along with the large steric bulk of the amidine ligands may enforce the trans geometry. Electrochemical studies show a strong dependence of the oxidation potential on the substituent groups despite their remote position. DFT calculations indicate that the HOMO consists of Ni-ligand p* orbitals with a significant contribution from the amidine ligands. © Springer Science+Business Media B.V. 2012.