ELECTRONIC-ENERGY TRANSFER IN BIMETALLIC RU-OS COMPLEXES CONTAINING THE 3,5-BIS (PYRIDIN-2-YL)-1,2,4-TRIAZOLATE BRIDGING LIGAND

The luminescence and photochemical properties of the two isomeric heterobimetallic [(bpy)2Ru(bpt)Os(bpy)2]3+ and [(bpy)2Os(bpt)Ru(bpy)2]3+ complexes have been investigated (bpy = 2,2'-pyridine; bpt- = 3,5-bis(pyridin-2-yl)-1,2,4-triazolate ion). The properties of the two isomeric compounds are compared with those of the corresponding dinuclear homometallic inert and exhibit luminescence only from the Os-based component. Excitation in the Ru-based component is followed by almost-equal-to 100% efficient energy transfer to the Os-based component. The energy-transfer mechanism is briefly discussed. The one-electron oxidation products (which contain Os in the 3 + oxidation state) are not luminescent because of the presence of a low-energy intervalence transfer level.