Quantum mechanical studies of isomeric and conformeric structures of methyl‐chloro‐peroxide

Abstract

Ab initio quantum mechanical studies are carried out for the isomeric structures and the torsional potential of methyl-chloro-peroxide. These species are important intermediates in the atmospheric reactions of methyl, methoxy, and methylperoxy radicals with chlorine dioxide, chlorine monoxide, and atomic chlorine, respectively. The calculations indicate that the peroxide form, CH 3 OOCl, with a skew geometry for C, O, O, and Cl atoms, is the lowest minimum energy structure followed by CH 3 OClO. The CH 3 ClO 2 adduct is found to be much higher in energy. The calculated isomerization barriers are found to be relatively high to permit possible interconversion pathways.

Computational investigation of isomeric and conformeric structures of methyl iodoperoxide

“…Thus, CH 3 IO 2 is higher located than CH 3 OOI at the MP2 level by 44.2 kcal mol -1 with basis set A, 10.9 kcal mol -1 with basis set B, and 18.5 kcal mol -1 at the CCSD(T)/B level in agreement with the corresponding XClO 2 , XBrO 2 species, whose stability has been found to depend strongly on the electronegativity of the X partner (13,14,21,(24)(25)(26). The results are consistent with the relative stability order of the HIO 2 isomer, which is also the most unstable in the HOOI family, calculated to be 26.5 kcal mol -1 higher compared to the peroxide isomer HOOI.…”

“…The third isomer CH 3 IO 2 with a C s symmetry, presents the I-O multiple bond characteristics more enhanced because of the double pair of electrons that are shared with the terminal oxygen atoms. Thus, it presents the shortest I-O bond distance (1.807 Å with basis set A and 1.749 Å with basis set B) following the same trend as all X-O distances in the analogous YXO 2 , X = Cl, Br structures (13,14). The nature of the hypervalent halogen-terminal oxygen multiple bonding has been analyzed in great detail by Lee et al (21) and it has found to present important consequences not only in the bond distances, but in the relative stability of the isomers as well, as we shall see in the next section.…”

“…Five isomers, four interisomerization transition state configurations, and two conformational barriers were determined in total. Among the isomeric minimum energy structures, another novel species, the CH 2 IOOH isomer, was found, which like the CH 2 IOH species mentioned above, presents no analogs in the chemistry of lighter halo-methylperoxides (13,14).…”

Structural and relative stability studies of (IClO3) and (IBrO3) polyoxides

“…Indeed, an increasing stability associated with X-ClO 2 and X-BrO 2 compounds has been observed as the electronegativity of X fragment increases and the effect has been demonstrated explicitly for a number of halogen polyoxide families [38][39][40].…”

Theoretical Investigation of Halogen-Oxygen Bonding and Its Implications in Halogen Chemistry and Reactivity

“… (a) Reference [37], (b) reference [16], (c) reference [36], (d) reference [22], (e) reference [39], (f) reference [17], (g) reference [44], (h) reference [29], (i) reference [40], (j) reference [25], (k) reference [45], (l) reference [48]. …”