Spectroscopic (IR, Raman, UV–Vis) study and thermal analysis of 3d-metal complexes with 4-imidazolecarboxylic acid

In this work, the spectroscopic (IR, Raman, UV–Vis) and thermal properties of 3d metal complexes with 4-imidazolecarboxylic acid were studied in order to determine the effect of 3d metals [i.e., Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II)] on the electronic structure and physicochemical properties of the ligand. The spectroscopic studies showed that the 3d-transition metals stabilize the electronic system of 4-imidazolecarboxylic acid. Similar results were obtained previously for benzoic and pyridinecarboxylic acids. The complexes synthesized in an aqueous medium were hydrated, as determined by the elemental and thermogravimetric analysis. The complexes of 4-imidazolecarboxylic acid have the general formula: M(C3N2H3COO)x·nH2O where M = Mn, Fe, Co, Ni, Cu, Zn, x = 3 for iron complex, x = 2 for other complex and n = 0–3. Thermogravimetric analysis conducted in oxygen atmosphere showed that the complexes decompose to metal oxides. During the thermal decomposition process carbon monoxide, carbon dioxide and imidazole ring degradation products are released.