Studies on the Photochemistry of Chromium Hexacarbonyl in the Gas Phase: Primary and Secondary Processes

Article abstract of DOI:10.1021/ja00294a001

The photochemistry of Cr(CO)6, induced by pulsed laser excitation at 249 nm, has been studied with time resolved infrared laser absorption spectroscopy.This method allows us to determine the temporal evolution of the reactant and all major product species.We find that photoactivated Cr(CO)6 decays to yield Cr(CO)5 and CO.The CO product is translationally as well as ro-vibrationally excited.The Cr(CO)5 product is formed with sufficient internal energy to undergo rapid dissociation, yielding Cr(CO)4 and CO.Both decarbonylation reactions occur within 10^-7 s of the photoactivation laser pulse.Cr(CO)4 reacts with Cr(CO)6 at a rate of 1.8 (+/-0.3) x 10⁷ torr^-1 s^-1, yielding Cr2(CO)10.This binuclear complex has a lifetime of at least 10^-3 s under our experimental conditions.Cr(CO)4 reacts with CO to form Cr(CO)5 at a rate of 1.4 (+/-0.2) x 10⁶ torr^-1 s^-1.Cr(CO)5 reacts with CO to form Cr(CO)6 at a rate of 1.2(+/-0.2) x 10⁶ torr^-1 s^-1.