CH3OCH.+, a New Stable C2H4O.+ Isomer, and a Reassessment of the Oxirane.+ Potential Surface

Article abstract of DOI:10.1021/ja00258a013

The ^.+ isomer of structure ^.+ has been shown to be unambiguously generated by CO2 loss from ionized methyl glyoxylate. ΔH_f⁰ for this new ion was measured to be 224 +/- 1 kcal mol^-1.The ^.+ ion produced by the loss of CH2O from ionized 1,3-dioxolane and by the loss of HCOOH from ionized methoxymethyl formate was proposed to have the structure ^.+, ΔH_f⁰ = 206 +/- 2 kcal mol^-1.Ionized oxirane in either its ²B₁ or ²A₁ state was proposed to be generated by loss of CO2 from ionized ethylene carbonate at a threshold energy corresponding to a ΔH_f⁰ = 235 +/- 1 kcal mol^-1.The structure assignments were aided by observations of collisional activation and metastable ion mass spectra.The common fragmentations of ^.+ and ^.+ ions, loss of CH3^. and H^., take place at similar high internal energies, leading to large kinetic energy releases in the metastable ion decompositions.Interpretations of the observations were in keeping with recent high-level ab initio molecular orbital theory calculations, but detailed mechanisms could not be established.