Photoreactivity of the triphenylphosphine adduct of methyl(trioxo)rhenium(VII) induced by ligand-to-metal charge transfer excitation

Triphenylphosphine forms an adduct with MeReO3. The yellow colour of this compound is attributed to a (PPh3→ReVII) ligand-to-metal charge transfer (LMCT) absorption at λmax=380 nm. LMCT excitation (λirr=405 nm) leads to the reduction of Re(VII) to Re(V). This reaction has been previously observed as a thermal process (Herrmann et al., Organometallics 13 (1994) 4531).