Synthesis, spectroscopic and electrochemical properties of mononuclear and dinuclear bis(bipy)ruthenium(ii) complexes containing dimethoxyphenyl(pyridin-2-yl)-1,2,4-triazole ligands

Abstract

The ligands HL1 and H₂L2 and the complexes [Ru(bipy)₂L1]PF₆·2H₂O 1, [(Ru(bipy)₂)₂L2](PF₆)₂·7H₂O 2, {where HL1 = 3-(2′,5′-dimethoxyphenyl)-5-(pyridin-2″-yl)-1H-1,2,4-triazole, H₂L2 = 1,4-bis(5′-(pyridin-2″-yl)-1′H-1′,2′,4′-triazol-3′-yl)-2,5-dimethoxybenzene and bipy = 2,2′-bipyridyl}, have been prepared and characterised, by NMR, UV–vis and emission spectroscopies and by electrochemical measurements. X-Ray crystal structures of ligands HL1, H₂L2 and of the complex 1 are also reported. The dinuclear complex (2) exhibits a weak electronic interaction between the metal centres, which is modulated by the protonation state of the 1,2,4-triazole rings. The extent of the metal–metal interaction in these systems is compared with that observed in other pyridyl-1,2,4-triazole based dinuclear compounds of differing metal–metal distances.