Thermochemical kinetics of bromine nitrate, bromine nitrite, halogen hydroperoxides, dichlorine pentoxide, peroxycarboxylic acids, and diacyl peroxides

Heats of formation of BrONO2, BrONO, BrOOH, FOOH, FOOCl, CF3C(O)OOH, HC(O)OOH, CH3C(O)OOH, and [CH3C(O)O]2 are estimated from bond contributions taken from J. Phys. Chem.,100, 10150 (1996). They agree within ±2 kcal/mol with recent experimental or ab initio data. The resulting BDE(O(SINGLEBOND)O)=36 kcal/mol value in diacetyl peroxide requires the concerted assistance of exothermic C(SINGLEBOND)C(O) weakening in the transition state of its decomposition into free radicals. It also implies the existence of a previously unrecognized 12 kcal/mol nonbonded repulsion in acyl anhydrides. The formation of chloryl chlorate with ΔHf(O2ClOClO2)=50 kcal/mol, a marginally stable species toward dissociation into (ClO3+OClO), may account for observations made in the [O(3P+OClO] system at low temperatures.