A copper complex possessing two phases, i.e. α phase 2,2'-dimethyl-2,2'bipyridinium tetrachloro-copper(ii) α-CuCl 4 (N,N'-dimethyl-2,2'-H 2 bipy) (1) and β phase 2,2'-dimethyl-2,2'-bipyridinium tetrachloro-copper(ii) β-CuCl 4 (N,N'-dimethyl-2,2'-H 2 bipy) (2) has been synthesized via solvothermal reactions and structurally characterized by single-crystal X-ray diffraction. Complex 1 crystallizes in the space group C2/c of the monoclinic system with four formula units in a cell: