Structure variation due to ligand flexibility: Syntheses and structures of the copper(II) complexes [CU(APPy)] and [CU2(AEPy)2] where APPyH2 = Bis[3-(2-pyridinecarboxamido)propyl]-methylamine and AEPyH2: Bis[3-(2-pyridine-carboxamido)ethyl]methylamine