Abstract The crystal structures of three compounds containing bis(di-2-pyridylamine)copper(II) complex units have been determined by X-ray crystallographic methods; [Cu(dpyam)2(OH2)2](S4O 6) (1), [Cu(dpyam)2(CF3SO3)2] (2) and [Cu(dpyam)2(SO4)]2[Cu(dpyam)2 (OH2)2](PF6)2·2H 2O (3). In compound 1 the anions are uncoordinated, and each Cu(II) ion involves the elongated tetragonal octahedral geometry with two water molecules occupying the axial positions. Compound 2 consists of neutral mononuclear units, the Cu(II) environment being elongated tetragonal octahedral with two unidentate triflate anions coordinating in axial positions. Two crystallographically independent molecules are found in compound 3, one complex unit being centrosymmetric and octahedrally elongated, with two water molecules coordinated in the axial positions, the other predominately close to the distorted square-based pyramidal (4 + 1) stereochemistry of the CuN3ON′ chromophore which is best described as square-pyramidal cis-distorted octahedral (4 + 1 + 1*). The latter complex unit of compound 3 is the first example containing a cis-distorted octahedral coordination among the copper(II) complexes with divalent oxyanions. © 2002 Elsevier Science Ltd. All rights reserved.