Two new chelidamate complexes with the 4-methoxypyridine: A combined theoretical and experimental study

Abstract

Two new mixed chelidamate complexes, [M(chel)(mhpOCH(3))center dot 2H(2)O]center dot 2H(2)O [M = Ni(II) (1); Co(II) (2); chel: chelidamate or 4-hydroxypyridine-2,6-dicarboxylate; mhp: 4-methoxypyridine], were prepared and characterized through a combination of X-ray diffraction method, FT-IR and UV-Vis spectroscopy. The central M(II) ion in complex (1) and (2) is coordinated by the mhp nitrogen atom, the chel nitrogen and oxygen atoms and aqua oxygen atoms, forming the distorted octahedral geometry. Intra and intermolecular hydrogen bonds and pi-pi it stacking interactions appear to be effective in the stabilization of the crystal structures. Also, the fully optimized geometries and vibrational frequencies have been calculated using density functional theory (DFT)-B3LYP with 6-31G (d) basis set. The vibrational frequencies were interpreted by means of potential energy distribution (PED). The energetic behaviors of the complexes in methanol solvent were examined using by time-dependent DFT (TD-DFT) method by applying the polarizable continuum model (PCM). The molecular stability and charge delocalization were analyzed using natural bond orbital (NBO) analysis. (C) 2015 Elsevier B.V. All rights reserved.