UV LASER PHOTOLYSIS OF (ETA-6-C6H6)CR(CO)3 - TIME-RESOLVED INFRARED STUDIES OF GAS-PHASE (ETA-6-C6H6)CR(CO)X (X = 2 AND 1)

The time-resolved infrared absorption spectra of the coordinatively unsaturated (eta(6)-C6H6)Cr(CO)x (x = 2 and 1) species generated via UV laser photolysis of the gas-phase (eta(6)-C6H6)Cr(CO)3 are presented and discussed. The photofragments produced upon 355- and 266-nm photolysis are identified. (eta(6)-C6H6)Cr(CO)2 is the predominant product upon 355-nm photolysis, while both (eta(6)-C6H6)Cr(CO)2 and (eta(6)-C6H6)Cr(CO) are produced upon 266-nm photolysis with a ratio of (eta(6)-C6H6)Cr(CO)2;(eta(6)-C6H6)Cr(CO) of about 2:5. The rate constants for reactions of (eta(6)-C6H6)Cr(CO)2 and (eta(6)-C6H6)Cr(CO) with CO are measured and found to be (6.3 +/- 0.3) x 10(12) and (1.4 +/- 0.2) x 10(12) cm3 mol-1 s-1, respectively. The rate constant for reaction of (eta(6)-C6H6)Cr(CO)2 with CO lies between the corresponding values for spin-allowed and spin-disallowed reactions of other coordinatively unsaturated metal carbonyl species with CO.