Aqueous CH 3 ReO 3 bipy, which is formed by the addition of 2,2 -bipyridine (bipy) to a solution of CH 3 ReO 3 , displays a long-wavelength (CH 3 - → bipy) ligand-to-ligand charge transfer (LLCT) band at λ m a x = 360 nm. Light absorption by this band leads to photolysis according to the equation CH 3 ReO 3 bipy + H 2 O → CH 4 + bipyH + + ReO 4 - (φ = 0.28 at λ i r r = 366 nm). As shown in a previous study, the photolysis of the parent compound CH 3 ReO 3 proceeds in a similar manner to the bipy adduct, but requires shorter wavelength irradiation corresponding to (CH 3 - → Re V I I ) ligand-to-metal charge transfer (LMCT) excitation.