TIME-RESOLVED INFRARED-SPECTRUM OF THE MLCT EXCITED-STATE OF W(CO)5(4-CNPYR) (4-CNPYR = 4-CYANOPYRIDINE) - PHOTOPHYSICS AND PHOTOCHEMISTRY

Fast time-resolved infrared spectroscopy is employed to probe the lower metal to 4-CNpyr charge-transfer (MLCT) excited state of W(CO)5(4-CNpyr) (4-CNpyr = 4-cyanopyridine). On visible irradiation, the CO stretching vibrations shift to higher frequency, confirming that in this excited state the metal center is oxidized. The excited state decays back to the ground state and, via the LF excited state, decomposes to W(CO)5 and 4-CNpyr. The rate constants for these processes are equal (ca. 4 x 10(6) s-1), suggesting that there is a rapid equilibrium between the MLCT and LF states.