10.1021/jp983514h.s001
Michael J. Raiti
Michael J.
Raiti
Michael D. Sevilla
Michael D.
Sevilla
Density Functional Theory Investigation of the Electronic Structure and Spin Density
Distribution in Peroxyl Radicals
American Chemical Society
1999
terminal peroxyl oxygen atom
CH
lipid peroxyl radicals show
17 O
peroxyl radicals
density distribution
ROO
peroxyl group results
Density Functional Theory Investigation
Spin Density Distribution
butyl peroxyl radicals
17 O hfcc
Thiyl peroxyl radicals
vinyl peroxyl radicals
UHF
DFT
Spin density distributions
SOO
electron pair donor
B 3LYP level
methyl peroxyl radicals
1999-03-02 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Density_Functional_Theory_Investigation_of_the_Electronic_Structure_and_Spin_Density_Distribution_in_Peroxyl_Radicals/3727398
The electronic structure and spin density distribution of peroxyl radicals are investigated by density functional
theory (DFT) at the B3LYP level. Results found for superoxide anion and <i>tert</i>-butyl peroxyl radicals at a
variety of basis sets suggest that 6-31G is the most appropriate basis set for calculation of hyperfine coupling
constants (hfcc's) of carbon-based peroxyl radicals. Calculation of parallel <sup>17</sup>O hfcc's [<i>A</i><sub>∥</sub>(<sup>17</sup>O)] for a series of
substituted methyl peroxyl radicals with the 6-31G basis set yielded calculated values with a maximum deviation
of 2.2% from experiment. Spin density distributions estimated from experiment <i>A</i><sub>∥</sub>(<sup>17</sup>O) are compared to
theoretical estimates from Mulliken orbital population analysis. Electronegative substitution at the carbon
alpha to the peroxyl group results in an increase of terminal oxygen hyperfine coupling and spin density,
shortening of C−O, and lengthening of O−O. In cases involving significant steric hindrance, however, C−O
bond shortening was prevented. <i>A</i><sub>∥</sub>(<sup>17</sup>O) values for the terminal peroxyl oxygen atom correlate well with Taft
σ* substitutent parameters for the R group in the peroxyl radicals (ROO<sup>•</sup>). Thiyl peroxyl radicals are
reinvestigated using B3LYP for comparison to previous theoretical work at UHF level. This resulted in
confirmation that the effect of the addition of an electron pair donor (hydroxide ion) to CH<sub>3</sub>SOO<sup>•</sup> is to alter
the spin density distribution in the peroxyl group. Structural models of lipid peroxyl radicals show that vinyl
peroxyl radicals may be distinguished from saturated, allylic, and ester-based peroxyl radicals on the basis of
hyperfine coupling constants.