Gravar-mail: catena-Poly[[bis­(1-ethyl-1H-imidazole-κN (3))cadmium]-di-μ-chlorido-[(1-ethyl-1H-imidazole-κN (3))cadmium]-di-μ-chlorido-[(1-ethyl-1H-imidazole-κN (3))cadmium]-di-μ-chlorido-[bis­(1-ethyl-1H-imidazole-κN (3))cadmium]]