Photophysical studies of tungsten carbonyl W(CO)5L complexes. Multiple-state luminescence of W(CO)5(4-cyanopyridine) in fluid and glassy solutions

Electronic absorption spectra, luminescence spectra, excitation data, and luminescence lifetimes have been recorded from W-(CO) 5 (4-CNpy) and W(CO) 5 (pip) (4-CNpy=4-cyanopyridine; pip=piperidine) complexes in methylcyclohexane solutions at 210−313 K and in EPA glasses at 77 K. The results illustrate that W(CO) 5 (4−CNpy) is a multiple-state emitter displaying dual emission bands at any of the measured temperatures; the emitting levels are assigned to metal to ligand charge-transfer (MLCT) excited states that are predominantly of triplet character