A copper complex of an unusual hy­dr­oxy–carboxyl­ate ligand: [Cu(bpy)(C4H4O6)]

A copper(II) complex, (2,2′-bi­pyridine-κ2N,N′)[2-hy­droxy-2-(hy­droxy­methyl-κO)propane­dioato-κ2O1,O3]copper(II), [Cu(C4H4O6)(C10H8N2)], containing the unusual anionic chelating ligand 2-(hy­droxy­meth­yl)tartronate, has been synthesized. [Cu(bpy)2(NO3)](NO3) was mixed with ascorbic acid and Dabco (1,4-di­aza­bicyclo­[2.2.2]octa­ne) in DMF (dimethylformamide) solution in the presence of air to produce the title compound. The structure consists of square-pyramidal complexes that are joined by Cu⋯O contacts [2.703 (2) Å] into centrosymmetric dimers. The C4H4O62− ligand, which occupies three coordination sites at Cu, has previously been identified as an oxidation product of ascorbate ion.