QUANTITATIVE STRUCTURE-STABILITY RELATIONSHIPS FOR OXIDES AND PEROXIDES OF POTENTIAL ATMOSPHERIC SIGNIFICANCE

A critical analysis of the most recent experimental and ab initio ther mochemical data on gas-phase species reveals that (1) isodesmic metath etical reactions among simple oxides, 1/2XOX + 1/2YOY <-> XOY, and tho se exclusively involving peroxides 1/2XOOX + 1/2YOOY <-> XOOY, are nea rly thermoneutral (Delta H-t = 0 +/- 3 kcal/mol), but exchange reactio ns between oxides and peroxides, XOX + YOOY <-> YOY + XOOX, are genera lly not, (2) bond additivity values BAV[X-(O-O)-X]'s for the contribut ions of the peroxide bond to the heats of formation of H-, C-, N-, S-, F-, and Cl-containing peroxides decrease linearly with Pauling electr onegativities chi(X)'s and (3) semiempirically evaluated (MOPAC) therm ochemical datasets, even when inaccurate in absolute terms, are intern ally consistent with such rules. These findings happen to provide the basis for the rapid and systematic assessment of the stability of nove l oxides and peroxides. In this paper, that focuses on species that co uld be formed in the terrestrial atmosphere, we briefly discuss XOO-H bond energy trends in hydroperoxides, the existence of stable and meta stable peroxy XOO(.) radicals, the thermochemistry of peroxyacyl nitra tes, of Br- and S-containing peroxides, and the mechanism of the (FO ClO), (FO + NO2), (OH + OClO), (HO2 + ClO), (ClO + NO2), and (ClO + N O3) reactions, among other issues.