Fe(III), Cu(II) and U(VI) binuclear complexes with a new isothiosemicarbazone ligand: Syntheses, characterization, crystal structures, thermal behavior and theoretical investigations

Abstract

A new Schiff base ligand, salicylaldehyde S-benzylisothiosemicarbazone.hydrochloride (H2L∙HCl), and three new binuclear complexes of iron(III), copper(II) and uranium(VI) of this ligand with general formulas [μ2-O-(FeLSal)2] (1), [μ2-O-(CuLSCN)2].2H2O (2) and TEAH[(UO2(LSal))2-μ2-OAc] (3), (Sal: salicylaldehyde, SCN: thiocyanate, OAc: acetate, TEAH: triethylammonium) were synthesized and characterized by elemental analysis, IR and UV-Vis spectroscopy; and TGA technique. The solid-state structures of the complexes were also determined by single crystal X-ray diffraction. The metal atoms in complexes 1, 2 and 3 adopt distorted square pyramidal, square pyramidal and pentagonal bipyramidal geometries respectively. The strength of the bonding in these complexes and the formation of pure metal oxide residues by thermal degradation of the complexes were investigated and confirmed by thermogravimetric studies. Furthermore, computational studies of the new complexes were performed by DFT methods. Geometry optimization and natural bond orbital analysis of the complexes are discussed.