A series of hydrogen bond mediated dinuclear nickel(II) complexes with reduced Schiff base ligands: An insight into the nature of their short intermolecular hydrogen bonds

Abstract

A series of isostructural centrosymmetric hydrogen bonded dimeric nickel(II) complexes of general formula, [Ni2(HL)2(DMSO)2(H2O)2]X {where H2L = N2O4 donor reduced Schiff base ligand, [H2L1=(2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(6-methoxyphenol) and H2L2=(2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(6-ethoxyphenol)] and X = counter anion}, are synthesized and characterized by elemental analysis, infrared and electronic spectra. The structures of all complexes have been confirmed by single crystal X-ray diffraction analysis. Each complex forms O⋯H⋯O hydrogen bonded dimer in the solid state, where the O⋯O distance is very short, ranging from 2.424(3) to 2.437(3) Å. The hydrogen bonds are very strong as can be seen from the DFT estimated energy of these hydrogen bonds. Non-covalent interaction plot (NCI plot) index has been used to characterize them.