The effect of the carbonyl moiety on the spin density delocalization in the iminoxy radicals. Hybrid density functional studies

UB1LYP method was used to study the influence of carbonyl group in 1,2-diphenyl-1-oxoethan-2-iminoxyl and 1-oxoethan-2-iminoxyl, on radical structure and unpaired electron spin density distribution. A significant change of radical properties was found due to the second carbonyl group in 2,4-dioxopenthan-3-iminoxyl and 1,3-dioxopropan-2-iminoxyl. A specific impact of the carbonyl groups on the EPR hyperfine couplings with 1H and 13C nuclei (calculated at UB1LYP/EPR-III level in comparison with the experimental data) was determined for the stable isomeric forms of the radicals.