Structures, Vibrational Spectra, and Relative Energetics of CH₃COIO₃ Isomers

Abstract

The structures, vibrational spectra, relative energetics, and enthalpies of formation of CH 3 COIO 3 isomers have been investigated with B3LYP, B3P86 and B3PW91 methods in conjugation with the 6-31＋G(d), 6-311＋G(d,p) and 6-311＋＋G(3df,3pd) basis sets. The CH 3 COOIO 2 structure was found to be the most stable form among the isomers with an estimated enthalpy of formation of -314.6 kJ•mol -1 . The enthalpies of formation for CH 3 COOOOI, CH 3 COOOIO and CH 3 COIO 3 are -180.7, -184.9 and -50.6 kJ•mol -1 , respectively. The implication of the formation of CH 3 COIO 3 isomers from the atmospheric cross-reactions of the acetylperoxy (CH 3 COO 2 ) and iodine monoxide (IO) radicals was examined and the possible dissociation products of the most likely CH 3 COIO 3 isomers were determined.