In the title salt, (C12H20N2)[CuCl4], the CuII atom occupies a general position in a flattened tetra­hedral environment by Cl ligands, characterized by Cl—Cu—Cl angles of 134.04 (3) and 137.18 (4)°. The six-membered piperazinediium ring adopts a chair conformation. The organic cation and inorganic anion inter­act through N—H⋯Cl and C—H⋯Cl hydrogen bonds, forming a three-dimensional network.

A novel Cd(II) coordination polymer [Cd(C 4 H 11 N 2 )(l-Cl) 2 Cl] n ÁnH 2 O with a supramolecular structure has been synthesized by reaction of CdCl 2 2Á5H 2 O with piperazine. The compound was investigated by X-ray diffraction, electrochemistry, and IR spectroscopy. The CdCl 3 (C 4 H 11 N 2 )ÁH 2 O entity in the compound forms a 1D coordination polymer as a result of the bridging function of the chlorine atoms Cd-Cl 2 -Cd. Adjacent 1D coordination polymers are connected by (O,N,C)-H…Cl, (O,N)-H…Cl, and N-H…O hydrogen bonds, generating a three-dimensional supramolecular network. With this atomic arrangement, the complex can form an electroactive film on a platinum electrode by anodic oxidation in acetonitrile solution.