Synthesis and crystal structure of and DFT calculations on bisglycinato-bis(p-hydroxymethylpyridine)nickel(II)

Abstract

A new Ni(II) complex of bisglycinato-bis(phydroxylmethylpyridine) was synthesized and characterized by elemental analysis, IR, UV-Vis spectroscopy and X-ray single crystal diffraction analysis. The thermal stability of the title complex was also determined. The complex adopts a distorted octahedral geometry and possesses inversion symmetry with the Ni(II) ion as the center of inversion. Density function theory (DFT) calculations of the structure, electronic absorption spectra, electron structure and natural population analysis (NPA) at the B3LYP/LANL2DZ level of theory were performed. The predicted geometric parameters and electronic spectra were compared with the experimental values and they supported each other. The NPA results indicate that the electronic transitions were mainly derived from the contribution of an intra-ligand (IL) transition, a ligand-to-metal charge transfer (LMCT) transition and a d-d transition. The electron structure calculations suggest that the central Ni(II) ion uses its 4s and 3d orbitals to form covalent bonds with coordinated N and O atoms. The calculated bond orders are also consistent with the thermal decomposition results. Based on vibrational analysis, the thermodynamic properties of the title complex were predicted and the correlative equations between these thermodynamic properties and temperature are also reported.