REACTIONS OF MN+ WITH I-C4H10, NEO-C5H12, (CH3)2CO, CYCLO-C3H6, AND CYCLO-C2H4O - BOND-ENERGIES FOR MNCH2+, MNH, AND MNCH3

The reactions of Mn+ with isobutane, neopentane, acetone, cyclopropane, and ethylene oxide are studied as a function of translational energy in a guided ion beam tandem mass spectrometer. The electronic state of the Mn+ ions is varied by altering the ionization technique. The a5S and a5D excited states are found to be more reactive than the a7D ground state, although formation of MnCH3 shows less of an effect than the other major reactions. The mechanisms for these processes are discussed and reaction thresholds are used to determine D°(Mn+-CH3) = 2.23 ± 0.10 eV, D°(Mn-H) = 1.31 ± 0.19 eV, D°(Mn-O) = 3.71 ± 0.26 eV, and D°=(Mn+-CH2) = 3.06 ± 0.13 eV. Only lower and upper limits for D°(Mn-CH3) of 0.55 ± 0.17 and 1.3 eV can be obtained. These bond strengths are compared to previous determinations and to theoretical calculations. The results for MnH, MnCH2+, MnCH3, and MnCH3+ are found to be consistent with promotion energy-bond strength correlations. © 1990 American Chemical Society.