The role of the metal connectors AgNO3, Cu2I2 and CuCl2 in co-ordination-polymer formation using the N2S2 ditopic ligand 1,4-bis(2-pyridylmethylsulfanylmethyl)benzene

The extended-reach ligand 1,4-bis(2-pyridylmethylsulfanylmethyl)benzene (L) was prepared by base coupling of 2-(chloromethyl)pyridinehydrochloride and 1,4-bis(sulfanylmethyl)benzene. This new ligand was treated with metal connectors AgNO3, CuX (X = Cl, Br or I) and CuCl2 to give co-ordination polymers. The crystal structures of [Ag-2(L)(NO3)(2)](infinity), [Cu-2(L)I-2](infinity) and [Cu(L)Cl-2](infinity) were determined. Comparison of the structures showed that the anion influenced the mode of metal binding with chelating or bridging modes being observed. The anion also influenced the nature of the packing, with the silver polymer forming a three-dimensional array containing clathrated water ladders while the copper polymers existed as related one-dimensional polymers. The remarkable feature of these structures is that while the silver polymer showed extensive intermolecular interactions, the copper polymers, despite the prevalence of aromatic rings, each displayed only one type of CH/pi interaction.