[Cu (2, 9-dimethyl-1, 10-phenanthroline) 2] 2+ and [Cu (6, 6′-dimethyl-2, 2′-bipyridine) 2] 2+/+ complexes with no coordinated solvent molecule were synthesized and the crystal structures were analyzed: the coordination geometry around the Cu (I) center was in the D2d symmetry while a D2 structure was observed for the four-coordinate Cu (II) complexes. Coordination of a water or an acetonitrile molecule was found in the trigonal plane of the ...