Multinucleating 2,2′ : 6′,2″-terpyridine ligands as building blocks for the assembly of co-ordination polymers and oligomers

Abstract

The co-ordination properties of the tridentate ligand 2,2′ : 6′,2″-terpyridine (terpy) make it an ideal structural unit from which to assemble co-ordination oligomers and polymers with a linear connectivity about the metal centre. The dinucleating ‘back-to-back’ 2,2′ : 6′2″-terpyridine ligands 6′,6″-bis(2-pyridyl)-2,2′ : 4′,4″ : 2″,2‴-quaterpyridine L1 and 1,4-bis(2,2′ : 6′,2″-terpyridin-4′-yl)benzene L2 give rise to a linear connectivity at the ligand, whereas 1,3,5-tris(2,2′ : 6′,2″-terpyridin-4′-yl)benzene L3 is a trinucleating species which can give rise to arrays with a connectivity of three at the ligand. The co-ordination oligomers [(X-terpy)RuLRu(X-terpy)]4+(L = L1 or L2) and [{(X-terpy)Ru}3L3]6+(X-terpy = 4′-substituted 2,2′ : 6′,2″-terpyridine) have been prepared and characterised for a variety of electron-donating and -withdrawing substituent groups X.