Water−Chloride and Water−Bromide Hydrogen-Bonded Networks: Influence of the Nature of the Halide Ions on the Stability of the Supramolecular Assemblies

Two compounds, namely, [TTPH2](Cl)2·4H2O (1) and [TTPH2](Br)2·4H2O (2), (TTP = 4′-p-tolyl-2,2′:6′,2′′-terpyridine) were synthesized from purely aqueous media and characterized by physical techniques. In the solid-state structures of these compounds, interesting supramolecular assemblies are observed. In 1, an unusual staircase-like architecture of the tape of edge-shared planar water hexamer is of importance, where the chloride ions are at the two edges of the tape. In 2, the polymeric nature of the water−bromide assembly is of interest, where discrete open-cube water octamers are doubly bridged by bromide ions. Semiempirical and DFT calculations confirm that the nature of the anion indeed affects the topology of the water−halide assemblies. We conclude that the protonated [TTPH2]2+ species can act as appropriate receptors for halide ions, which in turn act as a matrix for the formation of polymeric 1D water−halide assemblies.