Use of the Ni(dithiooxalate) 2 2− unit as a molecular tecton in crystal engineering

The use of NH⋯XM (X = Cl, Br) supramolecular synthons based on anionic perhalometallate hydrogen bond acceptors and cationic, usually pyridinium, N–H donors has previously allowed controlled crystal synthesis. The use of different molecular tectons (building blocks) with new but analogous synthons to generate a more diverse range of crystal structures is described. The nickel(II) bis(dithiooxalate) dianion (B) is shown to hydrogen bond effectively to a variety of pyridinium cations, yielding structures with motifs of planned dimensionality and form. The structural mimicry of the [PtCl4]2− tecton by B is described and analysed in the structures of [4,4′-H2bipy][Ni(S2C2O2)2] (1), [HNC5H4CO2H-4]2[Ni(S2C2O2)2]·2H2O (2), [HNC5H4CO2H-3]2[Ni(S2C2O2)2] (3), [H2NC5H10CO2H-4]2[Ni(S2C2O2)2] (4) and [HN(Me)C5H10CO2H-4]2[Ni(S2C2O2)2] (5). The chelating dithiooxalate–HN interaction is a robust and reliable synthon even in the presence of alternative donors and acceptors. The carbonyl functions are also potent hydrogen bond acceptors in the plane of the anion.