A copper complex of an unusual hy-droxy-carboxyl-ate ligand: [Cu(bpy)(C4H4O6)].

A copper(II) complex, (2,2'-bi-pyridine-κ2 N,N')[2-hy-droxy-2-(hy-droxy-methyl-κO)propane-dioato-κ2 O 1,O 3]copper(II), [Cu(C4H4O6)(C10H8N2)], containing the unusual anionic chelating ligand 2-(hy-droxy-meth-yl)tartronate, has been synthesized. [Cu(bpy)2(NO3)](NO3) was mixed with ascorbic acid and Dabco (1,4-di-aza-bicyclo-[2.2.2]octa-ne) 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 C4H4O6 2- ligand, which occupies three coordination sites at Cu, has previously been identified as an oxidation product of ascorbate ion.