Efficient generation of the ligand field excited state of tris-(2,2′-bipyridine)-ruthenium(II) through sequential two-photon capture by [Ru(bpy)3]2+ or electron capture by [Ru(bpy)3]3+

The relaxation dynamics and product distribution resulting from the decay of high lying excited states generated via sequential two-photon capture by [Ru(bpy)(3)](2+) or electron capture by [Ru(bpy)(3)](3+) have been investigated by flash photolysis and pulse radiolysis techniques. In comparison to the decay dynamics for monophotonic excitation, dramatically different relaxation dynamics have been observed. High-power flash excitation yields both the lowest lying metal-to-ligand charge transfer ((MLCT)-M-3) state and a new transient photoproduct associated with nonradiative decay through the photo dissociative metal-centered ((3)dd) excited state/s. The photoproduct is postulated to be [Ru-II(bpy)(2)(eta (1)-bpy)](2+) where the pendant pyridine has rotated to yield a transient that is stabilized by pi -bonded or a three-centered Ru-C-H agostic interaction.