Session Viewpoints on the 2019 International Symposium on Free Radicals Conference

Substituent Effect in the Cation Radicals of Monosubstituted Benzenes

“…On the other hand, those molecules which have either an odd number of electrons or have some orbitals singly occupied are the open-shell molecules, i.e., radicals, di-or biradicals, etc. It is more difficult to indicate the chemical disciplines in which the role of radicals is marginal than those for which it is considerable, e.g., [1][2][3][4][5][6][7][8][9][10]. Indeed, radicals appear in many organic reactions [11,12], inorganic coordination complexes in which metal ions have unpaired electrons [13][14][15], and modern industrial processes [16], i.e., radical polymerization [17].…”

“…(c) Linear correlations between the pEDA(D) descriptor and spin densities at the sum of the ring C atoms (ΣC), and C(ipso), C(p), C(ipso+p) atoms, as well as at the substituent R, and (d) the correlation between the pEDA(D) descriptor and spin densities at the sum of the ring C atoms (ΣC) with the substituent type shown. The following regression lines were, respectively, obtained: y = −0.74(5)x + 0.98(1); y = −0.70(3)x + 0.71(1); y = −0.41(3)x + 0.36(1); y = −0.29(4)x + 0.35(1); y = −0.75(5)x + 0.01(1). All results were obtained with the RO-DFT method, but analogous relationships also adhere to the U-DFT data.…”