Long-range chain orientation in 1-D co-ordination polymers as a function of anions and intermolecular aromatic interactions

Abstract

The influence of anions and intermolecular aromatic interactions on the orientation of one dimensional silver(I) co-ordination polymers has been studied. Reaction of AgX with 2,7-diazapyrene (diaz) (X = BF₄⁻ or NO₃⁻), 1,4-bis(4-pyridyl)butadiyne (pybut) (X = BF₄⁻, NO₃⁻, PF₆⁻ or MeCO₂⁻), 4,4′-bipy (X = BF₄⁻) or 1,4-bis(4-pyridylethynyl)phenylene (pyphe) (X = PF₆⁻) afforded products of general formula {[Ag(ligand)]X}_∞. All of the products have been structurally characterised by single crystal X-ray diffraction confirming that they exist as one-dimensional linear chain co-ordination polymers. The arrangement of the chains with respect to each other in the solid state is discussed and evaluated in terms of the relative co-ordinating ability of the anion used and the tendency of the N-donor ligand to adopt intermolecular aromatic interactions. For the complexes of diaz the overriding force in controlling chain orientation was shown to be π–π interactions between diaz ligands on adjacent chains. In the case of the pybut complexes the most dominant forces were shown to be metal–anion interactions with aromatic π–π interactions and Ag⋯Ag interactions playing a less influential role. In the case of {[Ag(pyphe)]PF₆}_∞ Ag⋯aromatic interactions are important in the overall arrangement of adjacent chains.