Triple helicates and planar dimers arising from silver(i) coordination to directly linked bis-pyridylimine ligands

Silver(i) coordination is investigated for three ligands of the pyridine-azine class, in which two pyridylimine binding units are linked directly through the imine nitrogen atoms. ¹H NMR, X-ray analysis and ESI mass spectrometry indicate the presence of a range of metallo-supramolecular architectures in solution for all three ligands. X-Ray analysis confirms the solid state structures for a dinuclear triple helicate containing five-coordinate silver centres and a dinuclear dimer in which the silver ions are three-coordinate with long range stabilising interactions to trifluoromethanesulfonate counter-ions. A tetranuclear grid-like array is also implied as a component of the solution library. The five-coordinate silver(i) ions in the triple helicate result in a hetero-ligand system with two ligands oriented in a head-to-tail fashion. This is distinct from the triple helicates formed with octahedral metals such as an iron(ii) triple helicate also crystallographically characterised herein.