Anomalous effect of non-alternant hydrocarbons on carbocation and carbanion electronic configurations

Abstract

Simple rules based on canonical structures allow for the prediction of a new class of triplet carbocation and carbanion species.

Demonstration of Baird's rule complementarity in the singlet state with implications for excited-state intramolecular proton transfer

“…[12][13][14][15] While numerous studies 10 have been conducted to investigate the excited-state aromaticity of various annulenesestablishing Baird's rule as a useful convention for understanding electronic states-the application of excited-state aromaticity to rationalize and design photochemical properties is less developed and predominantly focused on triplet aromaticity. [16][17][18][19] The goal of this work was to apply Baird's rules to interpret the unconventional behavior of benzoxazole fluorophores that undergo excited-state intramolecular proton transfer (ESIPT), where traditional strategies to red-shift the fluorescent wavelength instead lead to blue-shifted emission. 20,21 In doing so, we demonstrate the complementarity of Baird's rule, where lower aromaticity in S 0 leads to lower antiaromaticity in S 1 .…”

Anomalous Electronic Properties of Iodous Materials: Application to High-Spin Reactive Intermediates and Conjugated Polymers

“…Heavy atoms, like iodine, exceed the boundary of the employed split-valence basis set and the equivalent valence basis set (see Table S1 in the Supporting Information), which was initially constructed by Radom and others for carrying out Gaussian-2 (G2) theoretical calculations on iodine-containing molecules, is obtained from the basis set exchange database. , A reason for selecting this level of theory is that it has been benchmarked extensively for singlet–triplet gaps for these reactive intermediates. A recent benchmarking study gave an root-mean-square deviation (RMSD) error of 2.3 kcal/mol for computing the singlet–triplet gaps for hypovalent reactive intermediates including carbenium ions, oxenium ions, and carbenes, for a test set compared to experimentally determined values . Although iodine-containing moieties were not discussed in that benchmarking study, various substituents were investigated, which makes us believe that the computational method in this work is adequate to evaluate the singlet–triplet gaps for iodous reactive intermediates and conjugated oligomers.…”

“…A recent benchmarking study gave an root-mean-square deviation (RMSD) error of 2.3 kcal/mol for computing the singlet−triplet gaps for hypovalent reactive intermediates including carbenium ions, oxenium ions, and carbenes, for a test set compared to experimentally determined values. 58 Although iodine-containing moieties were not discussed in that benchmarking study, various substituents were investigated, which makes us believe that the computational method in this work is adequate to evaluate the singlet−triplet gaps for iodous reactive intermediates and conjugated oligomers. To determine the ground electronic states of the benzylic cationic reactive intermediates in this work, the singlet− triplet energy gap (ΔE ST ) was calculated by subtracting the lowest triplet energy from the lowest singlet energy (eq 1).…”

Azulene Moiety as Electron Reservoir in Positively Charged Systems; A Short Survey

“…These positions have different charges, therefore different reactivity. In comparison with other benzenoid hydrocarbons, the difference between the small highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) ensures its remarkable chemical, electronic or optical behavior [6]. Scheme 3.…”