DFT studies of ONO Schiff bases, their anions and diorganotin(IV) complexes: Tautomerism, NBO and AIM analysis

► Energy data are in agreement with the keto-amine tautomeric form resulted from X-ray studies. ► QTAIM topological analysis of electron density for some ligands and their organotin(IV) complexes. ► Comparative study of electron density in ligands and their organotin(IV) complexes at AIM and NBO methods. ► The strength of the metal-ligand bonds can be evaluated through AIM and NBO calculations.