Di-μ-azido-di­azidodi-μ-oxalato-di­histamine­tetra­copper(II) 0.9-hydrate

The title compound, [Cu(4)(C(2)O(4))(2)(N(3))(4)(C(5)H(9)N(3))(2)]·0.9H(2)O, contains a tetranuclear Cu(II)-based molecule composed of two oxalate-bridged Cu(II) dimers linked through end-on azide ions and related by an inversion center. The tetranuclear unit contains two crystallographically independent Cu(II) ions. One Cu(II) ion coordinates to two N atoms of a histamine mol­ecule, two O atoms of a bridging oxalate ligand, and an N atom of an end-on bridging azide ligand, leading to an elongated square-pyramidal coordination geometry in which the azide ion occupies the axial position. The other Cu(II) ion, which has a square-planar coordination geometry, is coordinated by two O atoms of a bridging oxalate ligand and two N atoms of two different azide ligands, one which is bridging. In the crystal, a two-dimensional network parallel to (010) is formed by N—H⋯N and N—H⋯O hydrogen bonds. A partially occupied solvent water mol­ecule refined to an occupancy of 0.447 (5). Two of the azide ligands were refined as disordered over two sets of sites with refined occupancies in the ratios 0.517 (8):0.483 (8) and 0.553 (5):0.447 (5).