Coordination properties of warfarin towards Pr(III) predicted from DFT and FT-IR studies

Abstract

The coordination behavior of warfarin towards Pr(III) in Pr(L) 3·5H 2O complex (L – warfarin) is investigated through molecular modeling at B3LYP/6-31G(d,p) level and consequent exhaustive comparative vibrational analysis of the ligand and the complex. The calculated NPA charges, Fukui functions and MEP values of the anionic ligand in solution pointed out that the oxygen atoms of the deprotonated hydroxyl and the coumarin carbonyl groups are the most probable reactive sites upon coordination. The metal–ligand binding mode of warfarin is predicted through molecular modeling and energy estimation of different Pr(III)–warfarin structures. In the most stable model structure, the ligand–metal binding is realized through the oxygen of the deprotonated OH group and the oxygen of the keto C O group in pseudo-octahedral polyhedron. The suggested metal–ligand binding mode is confirmed by comparative vibrational analysis of the free ligand and various model structures with different metal–ligand binding modes.