Synthesis, spectroscopic studies, X-ray crystal structures, electrochemical properties and DFT calculations of three Ni(II) complexes of aroyl hydrazone ligands bearing anthracene moiety

Two square planar Ni(II) complexes of general formula NiL2 and an octahedral Ni(II) complex of formula Ni(LH)(2)Cl-2 have been synthesized and characterized, where LH and L are protonated and deprotonated forms of bidentate hydrazone ligands. The spectroscopic and cyclic voltammetric studies of these complexes are also reported. X-ray crystal structure determination of the three complexes show that in two of the complexes Ni(II) have a N2O2 donor environment in a square planar geometry, while in the remaining one Ni(II) is in a distorted octahedral coordination environment of N2O2Cl2 donor atoms. The role of H-bonding interactions in determining the octahedral versus square planar geometry of Ni(II) is discussed. DFT calculations are used to understand the nature of the frontier orbitals. (C) 2014 Elsevier Ltd. All rights reserved.