COMPARISON OF THE C-H ACTIVATION OF METHANE BY M(C5H5)(CO) FOR M=COBALT, RHODIUM, AND IRIDIUM

The C-H activation reactions of methane by MCp(CO) (Cp = C5H5) for the metals cobalt, rhodium, and iridium have been studied using a variety of methods including a recently developed scaling scheme, different p erturbation theory methods, and also hybrid density functional theory methods. The main chemical problems investigated include the recent fi nding that CoCp(CO) is entirely inert toward alkanes in contrast to th e corresponding rhodium and iridium systems. Comparisons are made for CoCp(CO) between the reaction with methane and the reaction with CO, w hich is found experimentally to proceed fast. Also studied are the iso tope effects on the reaction in relation to other recent experiments. At the highest level of treatment, good agreement is found with all pr esent observations for these systems, but it should be pointed out tha t precise experimental information is lacking for many of the systems studied. Severe deviations between the results obtained at different c omputational levels are pointed out.