4,4′-Bipyridinium bis­(oxalato-κ(2) O (1),O (2))cuprate(II): an ion-pair complex

The title compound, (C(10)H(10)N(2))[Cu(C(2)O(4))(2)] or (4,4′-H(2)bpy)[Cu(ox)(2)] (bpy is 4,4′-bipyridine and ox is oxalate), is an ion-pair complex comprising a protonated 4,4′-bipyridinium dication and a square-planar dioxalatocopper(II) dianion. In the centrosymmetric dianion, the Cu(II) centre is coordinated by four O atoms from the two dicrete oxalate ligands [Cu—O = 1.9245 (19) and 1.9252 (17) Å], while the planar dications are also centrosymmetric. Inter-species N—H⋯O hydrogen bonds link the cations and anions into one-dimensional chains and, together with weak intra-ion C—H⋯O inter­actions, give a two-dimensional sheet structure.