Design, Spectroscopic Characterization and Theoretical Studies of Organotin(IV) and Organosilicon(IV) Complexes with Schiff Base Ligands Derived from Amino Acids

Abstract

A new series of organotin(IV) and organosilicon(IV) complexes were synthesized using the Schiff base ligands [2-((3,4-dimethoxybenzylidene)amino)-3-(1H-indol-3-yl)propanoic acid (L1H) and 2-((3,4-dimethoxybenzylidene)amino)-3-methylbutanoic acid (L2H)]. The synthesized compounds were characterized by IR, NMR (1H and13C), elemental analysis and theoretical studies. The molar conductivity values of the complexes in DMF implied the presence of non-electrolyte species. Spectral data showed that in these complexes the metal atoms are coordinated with the Schiff base ligand acts as a bidentate ON moiety, coordinating to the metal through its carboxylate oxygen and imine nitrogen. The IR spectra of the complexes showed large differences between νasy(COO) and νsy(COO), Δν (νasy(COO)–νsy(COO)) of 260-276 cm–1, indicating monodentate nature of the carboxylate group. Furthermore, the density functional theory (DFT) calculations were executed at the B3LYP/6-31G(d,p)/ LanL2DZ basis set of theory for the optimized geometry of Schiff base complexes. The structural parameters, bond length, bond angles, chemical potential, electronegativity, hardness, softness, global electrophilicity index have been studied theoretically by density functional theory (DFT) to support the experimental results.