A laser flash photolysis, matrix isolation, and DFT investigation of (η 6-C 6H 5Y)Cr(CO) 3 (Y = NH 2, OCH 3, H, CHO, or CO 2CH 3)

Abstract

The quantum yield for arene displacement from (η 6-C 6H 5Y)Cr(CO) 3 was measured in 1,1,2-trifluorotrichloroethane (Y = NH 2, OCH 3, H, CHO, or CO 2CH 3). Values of 0.24, 0.27, 0.15, 0.17, and 0.32 were obtained respectively ( λ exc. = 355 nm). These values are significantly higher than those measured for photoinduced arene loss in hydrocarbon solvents using the same excitation wavelength. Laser flash photolysis of (η 6-C 6H 5Y)Cr(CO) 3 in 1,1,2-trifluorotrichloroethane ( λ exc. = 355 nm) resulted in the rapid formation (<10 ns) of Cr(CO) 6. Matrix isolation experiments on (η 6-C 6H 5Y)Cr(CO) 3 (Y = H or CHO) at 12 K in CH 4 or CO-doped CH 4 matrixes using monochromatic irradiation confirmed the presence of two discrete excited states, one leading to CO-loss and the other to arene-loss. The results correlate with the calculated electron drift in the excited state derived from density functional theory and time dependent density functional theory calculations.