Synthesis and properties of four transition metal complexes of 5-mercapto-1H-tetrazole-1-acetic acid

► Four transition metal complexes with H2mtaa have been synthesized. ► The Zn(II) and Cd(II) complexes have 2D and 3D structures containing double helices, respectively. ► The carboxylate groups of the ligands bridge the Co(II)/Mn(II) ions into 2D sheet structures. ► Photoluminescence and magnetic properties of the complexes were investigated.