Coordination Geometries in Bis(di-2-pyridylamine)copper(II) Complexes. Crystal Structures of [CuL2](PF6)2, [CuL2(NO3)2] and [CuL2(NCS)1.5(ClO4)0.5][CuL2(NCS)]2(ClO4)2 (L = Di-2-pyridylamine).