New Ruthenium(II) Polypyridyl-Type Complexes with Oxadiazole Derivative Ligand

A new ruthenium complex, [Ru(L)(bpy) 2 ]·2PF 6 , (L = 3,5-di(2'-pyridyl)-1,2,4-oxadiazole), was synthesized and characterized. The assignment of chemical shift for [Ru(L)(bpy) 2 ]·2PF 6 was accomplished by HHCOSY technique. The cyclic voltammogram of [Ru(L)(bpy) 2 ]·2PF 6 shows a metal-centered Ru II /Ru III oxidation with potential at 1.35 V, as well as four reversible reduction waves with the former two potentials at -1.24 and -1.60 V, attributed to two bpy/bpy - process, and the latter two potentials at -1.86 and -2.16 V, attributed to L/L - and L - /L 2- , respectively. The absorption spectrum of the ruthenium complex was dominated by metal-to-ligand charge transfer (MLCT) band in the visible range, with absorption maxima appearing at 442 nm and molar extinction coefficient of 13 x 10 3 M -1 cm -1 . The phosphorescent emission band has been attributed to from MLCT triplet state.