trans-Bis[(1-ammoniopentane-1,1-diyl)diphosphonato-κ2O,O′]diaquacopper(II)

In the title compound, [Cu(C5H14NO6P2)2(H2O)2], the CuII 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 CuII 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 CuO6 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