trans-Bis[(1-ammonio­pentane-1,1-di­yl)diphospho­nato-κ(2) O,O′]diaqua­copper(II)

In the title compound, [Cu(C(5)H(14)NO(6)P(2))(2)(H(2)O)(2)], the Cu(II) atom occupies a special position on an inversion centre. It exhibits a distorted octa­hedral coordination environment consisting of two O,O′-bidentate (1-ammonio­pentane-1,1-di­yl)diphospho­nate anions in the equatorial plane and two trans water mol­ecules located in axial positions. The ligand mol­ecules are coordinated to the Cu(II) atom in their zwitterionic form via two O atoms from different phospho­nate groups, creating two six–membered chelate rings with a screw-boat conformation. The CuO(6) coordination polyhedron is strongly elongated in the axial direction with 0.6 Å longer bonds than those in the equatorial plane. Intra­molecular N—H⋯O hydrogen bonding helps to stabilize the mol­ecular configuration. The presence of supra­molecular —PO(OH)⋯O(OH)P— units parallel to (100) and other O—H⋯O and N—H⋯O hydrogen bonds establish the three-dimensional set-up.