Coordination compounds of heterocyclic azo derivatives. III. Co(II), Ni(II) and Cu(II) complexes of some arylazo-4,5-diphenylimidazole derivatives@@@Koordinatsverbindungen von heterocyclischen Azo-Derivaten, 3. Mitt.: Co(II)-, Ni(II)- und Cu(II)-Komplexe einiger Arylazo-4,5-diphenylimidazol-Derivate