Polymeric and mixed ligand complex of cobalt(II) and 4-hydroxybenzhydrazide: Crystal structure and vibrational spectroscopy

Reaction of CoSO4 and 4-hydroxybenzhydrazide in water/methanol solution resulted in polymeric complex with CO and NH2 groups of organic ligand, two water molecules and two oxygen atoms of two sulfate anions in metal coordination sphere. The X-ray analysis revealed that the complex is in the form of polymer chain of the helical structure formed due to sulfate bridge geometry and intra-chain hydrogen bonds. The variety of coordinated ligands is reflected in the vibrational spectra where six different metal–ligand modes were found. The bands related to stretching and bending vibrations of NH2, NH, OH groups as well as water molecules were located with help of hydrogen–deuterium substitution. For proposed band assignment the animation of DFT calculated normal modes was employed.