Coordination compounds of chelating ligands containing imidazole groups. Synthesis and characterization of copper(I) and copper(II) complexes of N,N,N',N'-tetrakis[(2-benzimidazolyl)methyl]-1,2-ethanediamine and the x-ray structure of an [N,N,N',N'-tetrakis[(2-benzimidazolyl)methyl]-1,2-ethanediamine]copper(II) cation