A convenient method for the preparation of barbituric and thiobarbituric acid transition metal complexes

Abstract

A convenient method for the preparation of barbiturate transition metal complexes: (i) Cr 3+, Mn 2+, Fe 3+, Zn 2+ and Cd 2+ ions with barbituric acid (H 2L) and (ii) Cr 3+ and Mo 5+ with 2-thiobarbituric acid (H 2L′) was reported and this has enabled seven complexes to be formulated as: [Cr(HL) 2(OH)(H 2O)]·H 2O, [Mn(HL) 2(H 2O) 2], [Fe 2(L)(OH) 3(H 2O) 4]·2H 2O, [Zn(HL) 2], [Cd(HL) 2], [Cr(HL′)(OH) 2(H 2O)]·H 2O and [Mo(HL′) 2]Cl. These new barbiturate complexes were synthesized and characterized by elemental analysis, molar conductivity, magnetic measurements, spectral methods (mid infrared, 1H NMR, mass, X-ray powder diffraction and UV/vis spectra) and simultaneous thermal analysis (TG and DTG) techniques. The molar conductance measurements proved that, all complexes of barbituric and 2-thiobarbituric acids are non-electrolytes except for [Mo(HL′) 2]Cl. The electronic spectra and magnetic susceptibility measurements were used to infer the structures. The IR spectra of the ligands and their complexes are used to identify the mode of coordination. Kinetic and thermodynamic parameters such as: E*, Δ H*, Δ S* and Δ G* are estimated according to the DTG curves. The two ligands and their complexes have been studied for their possible biological antifungal activity.