LASER-INDUCED FLUORESCENCE OF REACTIVE METALLOCENES (ETA-5-C5H5)2RE, (ETA-5-C5H5)2W, (ETA-5-C5H5)2MO AND (ETA-5-C5ME5)2RE

Laser-induced fluorescence spectra have been recorded for the title metallocenes isolated in low-temperature matrices. Excitation of the lowest energy ligand-to-metal charge-transfer states with a nanosecond pulsed laser induces relaxed fluorescence from the same excited states. The fluorescence lifetime of (η5-C5H5)2Re is 71.9 ± 1.3 ns, while the lifetimes of the remaining compounds are <10 ns. All the emission spectra show prominent vibrational progressions, but the spectra vary significantly with excitation wavelength as different conformations/matrix sites are probed. The corresponding excitation spectra reveal that the absorption spectra are composed of the sum of these inhomogeneous components. Evidence for electronic energy transfer between sites is found for (η5-C5Me5)2Re. © 1990 American Chemical Society.