[RuII(hedta)]− complexes of 2,2′-dipyridylamine (dpaH) and a bifunctional tethered analog, N,N,N′,N′-tetrakis(2-pyridyl)adipamide (tpada)

[RuII(hedta)L]− complexes (hedta3−=N-hydroxyethylethylenediamine-N,N,N′-triacetate); L=dpaH (2,2′-dipyridylamine) and tpada (N,N,N′,N′-tetrakis(2-pyridyl)adipamide)) have been studied by 1H NMR and electrochemical methods in aqueous solution. The bidentate rings of dpaH and tpada are differentiated as shown by NMR upon coordination to RuII due to differences in the local environment. The dpa–R headgroup of each ligand binds ‘in-plane’ with the en backbone of hedta3− and with one pyridyl ring being nearer the amine of hedta3− having the pendant glycinato group (matching the known arrangement with bpy (2,2′-bipyridine)). RuII/IIIE1/2 values follow the order dpaH (0.32 V)