Synthesis, antimicrobial activity and molecular modeling of cobalt and nickel complexes containing the bulky ligand: bis[N-(2,6-diisopropylphenyl)imino] acenaphthene.

Two cobalt and two Nickel complexes of bis[N-(2,6-diisopropylphenyl)imino]acenaphthene (Pr-BIAN) ligand, have been synthesized. These complexes, namely [Co(Pr-BIAN)Cl2] 1, [Co(OAc)2 (Pr-BIAN)2](ClO4) 2, [Ni(Pr-BIAN)(NO3)2] 3 and [Ni(Pr-BIAN)2](ClO4)2 4, were characterized by elemental analyses, molar conductance, spectral (IR, UV-Visible and NMR) and magnetic moment measurements. In these complexes the geometries about the metal center are significantly different. While for complexes 2 and 3 an octahedral structure is proposed, in complex 4, square-planar coordination with an almost perfect planar arrangement of two Pr-BIAN ligands around the nickel center is suggested. In 1, two imine nitrogen atoms of Pr-BIAN and two chloride atoms are coordinating in a tetrahedral fashion around the cobalt center. Molecular mechanics (MM+) and semiempirical molecular orbital calculations have been performed for the most biologically active complex 1 and its free ligand Pr-BIAN and compared with inactive ligand bis[N-(p-tolylphenyl)imino]acenaphthene 6, to get insight into their molecular structures and to learn more about their stable molecular conformations.