An Investigation into the Reactivity of Organometallic Noble Gas Complexes: A Time-Resolved Infrared Study in Supercritical Noble Gas and Alkane Solution at Room Temperature

A series of Group 7 organometallic noble gas complexes, (η⁵-C₅R₅)M(CO)₂L (M = Mn and Re; R = H, Me, and Et (Mn only); L = Kr and Xe) have been characterized in supercritical noble gas solution at room temperature using fast time-resolved infrared spectroscopy. The kinetics and activation parameters for the reaction of these complexes with CO were measured and compared to the analogous alkane complexes, (η⁵-C₅H₅)M(CO)₂(n-heptane) (M = Mn and Re). Evidence obtained from values of the activation enthalpies and experiments, in which the lifetimes of (η⁵-C₅R₅)Mn(CO)₂Xe (R = H, Me, and Et) were measured as a function of [CO] at a constant [CO]/[Xe] ratio, suggests that the reaction of the noble gas complexes with CO occurs mainly via a dissociative or dissociative interchange mechanism.