Cobalt(ɪɪ) and nickel(ɪɪ) bis(chelate) complexes with (N, O, O)-tridentate azomethine ligands: a quantum chemical study of stereoisomers with hexa-, penta-, and tetracoordinate central atoms

The molecular structures and relative energies of stereoisomers of the Coɪɪ and Niɪɪ bis(chelate) complexes composed of hexa-, penta-, or tetracoordinate metal atoms and (N, O, O)-tridentate azomethine ligands and having the MN2O2O2, MN2O2O, and MN2O2 coordination sites, respectively, were obtained from the B3LYP (PBE0, TPSSh)/6-311++G(d,p)) density functional calculations. Simulation of the mechanism of formation of the complexes revealed the energy preferableness of the structures with hexacoordinate central atoms.