Mass spectrometric study of the thermal decomposition of dimanganese decacarbonyl and dicobalt octacarbonyl

The free radicals •Mn(CO)5 and •Co(CO)4 have been produced by the pyrolysis of Mn2(CO)10 and Co2(CO)8 in graphite flow reactors. The effusing molecular beams from these reactors were analyzed mass spectrometrically. Evidence is presented for the following equilibria[Formula: see text]From the temperature dependence of the equilibrium constants, enthalpy changes of 24.9 ± 2 and 14.5 ± 2 kcal/mole, respectively, have been obtained. These enthalpy changes give D(Mn—Mn) = 21 ± 3 kcal/mole and D(Co—Co) = 13 ± 3 kcal/mole, which substantiate the earlier literature values based on electron impact measurements.