CONVERSION OF CH4 TO CH3OH - REACTIONS OF COO-2, CO+ WITH CH3OD AND D2O, AND CO+(CH3OD) WITH XE( WITH CH4 AND D)

The mechanisms and energetics involved in the conversion of CH4 to CH3 OH by CoO+ are examined by using guided ion beam mass spectrometry. Th e forward and reverse reactions, CoO+ + CH4 <-> Co+ + CH3OH, the colli sional activation of Co+(CH3OH), and the related reactions, CoO+ + D-2 <-> Co+ + D2O, are studied. It is found that the oxidations of methan e and D-2 by CoO+, both exothermic reactions, do not occur until overc oming activation barriers of 0.56 +/- 0.08 and 0.75 +/- 0.04 eV, respe ctively. The behavior of the forward and reverse reactions in both sys tems is consistent with reactions that proceed via the insertion inter mediates R-Co+-OH, where R = CH3 or H. The barrier is probably attribu table to a four-centered transition state associated with addition of RH across the CoO+ bond. In the Co+ + CH3OH system (where CH3OD labele d reactant is used), reactions explained by initial C-H and O-H activa tion are also observed. The reaction mechanisms and potential energy s urfaces for these systems are derived and discussed. Phase space theor y calculations are used to help verify these details for the CoO+ + D- 2 system. Thermochemistry for several species including CoOH+, CoD+, C oH, CoCH3+, Co+(CH3OD), CoOCH3+, and possibly OCoCH3+ is derived from measurements of reaction thresholds.