The title compound, [Co(C3H7NO)(H2O)5]SO4·C3H7NO, contains five aqua ligands, a CoII atom, a sulfate ion and both a coordinating and a non-coordinating di­methyl­formamide (DMF) mol­ecule. The DMF solvent mol­ecule lies between the complex units, which are located along the b axis. The sulfate ion is for charge balance. The CoII atom has distorted octa­hedral coordination geometry, being ligated by five aqua ligands and the O atom of the DMF ligand. O—H⋯O hydrogen bonds between the aqua ligands and the sulfate anion and non-coordinating DMF molecule lead to the formation of a three-dimensional network. Since all constituents lie on a mirror plane, the H atoms of all methyl groups and of one of the aqua ligands are equally disordered over two positions.

Novel mixed ligand complexes containing thiophene-2-carboxylic acid (HTCA) and imidazole (im) ligands, [M(TCA) 2 (H 2 O) 2 (im) 2 ] (M: Mn, Co, Cd) and [Cu(TCA) 2 (im) 2 ] were obtained. The complexes were characterized by X-ray single crystal diffraction. Also, spectroscopic (IR and UV-Vis), magnetic and thermal properties were investigated. The thiophene-2-carboxylate acted in a monoanionic monodentate manner and bonded to the metals via its carboxylate oxygen. The im ligands bonded to the metals via hydrogen free nitrogen atoms. The geometry around the metal centers was octahedral [MO 4 N 2 ] for Mn(II), Co(II) and Cd(II) complexes and square-planar [CuO 2 N 2 ] for the Cu(II) complex. Due to intermolecular interactions in the solid state, the Co(II), Mn(II) and Cd(II) complexes showed three-dimensional networks, while the copper complex was a one-dimensional network. In consideration of the anhydrous form of the complexes, the thermal stability of the complexes was of the following order: Co (273°C) > Cu (229°C) > Cd (175°C) > Mn (167°C).