A DFT quantum mechanical study of 3-hydroxy-4-pyrone and 3-hydroxy-4-pyridinone based oxidovanadium(IV) complexes

Oxidovanadium(IV) complexes have revealed interesting pharmacological properties which make them promising agents in the treatment of diabetes mellitus. A computational study of 17 complexes of oxidovanadium(IV) with 3-hydroxy-4-pyrone- and 3-hydroxy-4-pyridinone-based ligands was carried out at the density functional theory level. The geometry, electronic structure, and vibration modes at the metallic center were predicted, and their dependence on the nature of the ligand was evaluated. Slight distinctions between both classes of compounds were observed, namely the higher value of dipole moments and the smaller HOMO–LUMO energy gap for the 3-hydroxy-4-pyridinone-based complexes. The modes of vibration at the metallic coordination region do not vary significantly throughout the whole series, and a particular corrective scaling factor is proposed for the V=O stretching mode of this type of oxidovanadium(IV) complexes. The results presented here are of particular relevance since it was not yet possible to obtain X-ray diffraction data for the oxidovanadium(IV) complexes of 3-hydroxy-4-pyridinones, and also as the influence of the solvent, in particular the local interaction at the sixth coordination position, was considered.