Pendant-functionalised ligands for metallosupramolecular assemblies; ruthenium( II ) and osmium( II ) complexes of 4′-(4-pyridy1)-2,2′ : 6′,2″-terpyridine

The potentially tetradentate ligand 4′-(4-pyridyl)-2,2′ : 6′,2″-terpyridine (pyterpy) acts as a tridentate donor to iron(II), ruthenium(II) and osmium(II). The non-co-ordinated pyridyl group reacts with a range of electrophiles to give complexes containing the cationic ligands Hpyterpy and 4′-(4-methylpyridinio)-2,2′ : 6′,2″-terpyridine (mpyterpy) The electrochemical behaviour of these complexes has been studied and correlations between the redox potentials and Hammett σ+ parameters made.