Photophysics and Photochemistry of Pentacarbonyl(pyridine)tungsten(0) Complexes Which Luminescence in Fluid Solution

Article abstract of DOI:10.1021/ja00378a005

Luminescence data are reported for W(CO)5L complexes, where L=4-acetylpyridine, 4-benzoylpyridine, 4-cyanopyridine, and 4-formylpyridine, as solids and in fluid solution.Photosubstitution quantum yields (for the dissociation of L) have been recorded for these W(CO)5L complexes in several solvents with various irradiation wavelengths.Apparent activation energies for the W(CO)5L complexes in several solvents have been measured from the temperature dependencies of the emission and photoreactivity processes.Quenching of the emission and photoreactivity processes is reported for several quenchers; the results are used to bracket the energies of the emitting state for each complex.Two low-lying metal-to-ligand charge-transfer excited states are implicated in the radiative decay process.Possible excited-state schemes for these W(CO)5L complexes are discussed in accordance with the experimental observations.Excited-state absorption and primary photoproduct spectra have been recorded for the W(CO)5L complexes in methylcyclohexane and benzene by monitoring techniques.A common photoproduct is inferred, its spectrum being close to that of W(CO)5S, where S denotes solvent, following pulse laser photolysis of W(CO)6 as previously reported by us.