Photophysics of ion clusters formed between [Ru(bPY)3]2+ and the polyoxotungstate anion [S2W18O62]4-

The interactions between [Ru(bpY)(3)](2+) and the polyoxotung state anion [S2W18O62](4-) in acetonitrile solution were investigated using a combination of photophysics and optical and Raman spectroscopies. The presence of ion clusters of {[Ru(bPY)(3)][S2W18O62]}(2-) (K-2 = 7.7 x 10(5)) and [Ru(bpy)(3)](2)[S2W18O62] (K-1 = 1.0 x 10(6) Mol(-2) dm(-6)) are inferred. The 2:1 complex is weakly luminescent, with a lifetime at room temperature of 20 ns under aerobic conditions. Difference electronic absorption, excitation, and resonance Raman spectroscopies indicate that the tungstate anion participates in this transition. Under conditions where [Ru(bpy)(3)](2+) alone is photolabile, the ion clusters are photostable, with no photodecomposition or photoinduced ligand exchange reactions evident in acetonitrile. This characteristic is examined employing temperature-dependent luminescent studies which demonstrate that the observed activation energy and preexponential factor are considerably different from those of free [Ru(bpy)(3)](2+) and are characteristic of a photostable polypyridylruthenium complex.