Theoretical investigation of chlorofluorocarbon degradation processes: Structures and energetics of XC(O)O sub x intermediates (X = F, Cl)

Photodissociation of stratospheric chlorofluoromethanes leads to carbonyl dihalide CX{sub 2}O, whose further degradation is also initiated by a photodissociation step. The energetics of possible oxidation pathways involving XCO, XC(O)O, and XC(O)O{sub 2} radicals have been investigated by calculations at the UMP2/6-31G{sup *} and PMP2/6-31G{sup *} levels of ab initio molecular orbital theory. In the absence of experimental thermochemical data, calculated heats of reaction are used in discussions of the possible involvement of these intermediates in reactions of atmospheric significance.