Synthesis, spectroscopic, thermal and structural properties of some transition metal complexes of thiophene-2-carboxylic acid

In this study, the complexes containing thiophene-2-carboxylic acid (HTCA) and imidazole (im) ligants were synthesized and characterized by X-ray single crystal diffraction method. Also, spectroscopic (IR and UV-Vis.), magnetic and thermal properties were investigated. In the complexes, the thiophene-2-carboxylic acid acted as monoanionic monodentate manner and bonded to the metals via its carboxylate oxygen. The imidazole ligants bonded to the metals via its nitrogen atoms. The formula of the complexes were found as [M(TCA)2(H2O)2(im)2] (M: Mn, Co, Cd) and [Cu(TCA)2(im)2]. The geometry around the metal centers were found as octahedral [MO4N2] type for manganese, cobalt and cadmium complexes and found as square-planar [CuO2N2] type for copper complex. Magnetic susceptibility measurements showed the complexes were in low ligant field complexes. In the consideration of anhydrous form of the complexes, the thermal stability of the complexes was suggested as Co (273°C)>Cu (229°C)>Cd (175°C)>Mn (167°C).