Hydrocarbon σ‐radical cations

Abstract

The structure and transformations of radical cations derived from saturated hydrocarbons in the gas phase and solution may be, in most cases, predicted with high‐level computational methods. The review covers so‐called sigma‐radical cations, i.e., the species with partially broken CH and CC bonds. The radical cations formed from the small acyclic (methane, ethanes, and butanes), as well as cyclic (cyclopropane, cyclobutane, and rotanes) and polycyclic hydrocarbons were analyzed. © 2011 John Wiley & Sons, Ltd. WIREs Comput Mol Sci 2011 1 661–679 DOI: 10.1002/wcms.24 This article is categorized under: Structure and Mechanism > Molecular Structures

Toward an Understanding of Diamond sp2-Defects with Unsaturated Diamondoid Oligomer Models

“…50% of positive charge and 30% of spin density localized on the CH 2 and CH groups of the adamantane moiety. This is in line with our previous studies on the ionized adamantane, diamondoids and other cage compounds that form highly delocalized radical cations displaying several elongated CC and CH bonds and high degree of spin/charge delocalization.…”

Cation States of Ethane: HEAT Calculations and Vibronic Simulations of the Photoelectron Spectrum of Ethane

“…Calculations with both wave function and density functional methods found minimum energy geometries comprising interesting structural features. The lowest energy forms are a “diborane-like” structure in C 2 h symmetry and a “long-bond” structure of D 3 d symmetry, − deriving from the X̃ 2 E g and à 2 A 1g states, respectively. Photoelectron spectroscopy by Turner and workers , observed significant vibronic activity around 11–13 eV, ionization out of the 1e g and 3a 1g orbitals producing the cation states as mentioned above.…”

Endohedral σ-Diradical Nitrogen-Vacancy Diamond Nanoclusters with a Confined Magnetic Space and Strong Electronic Spin Couplings

“…N-substitution of one radical C • can reduce the vacancy center to be a triradical one. As demonstrated experimentally, such a NV defect center can be modified through excess electron injection (NV – ), further heteroatom doping (such as NNV or NBV with a N and a B surrounding a vacancy) or C-hydrogenation (NCHV), changing as the extra-electron-coupled triradical or diradicals. − They are very similar to the diradicaloids where two radical centers or unpaired electrons distribute at two different regions with relatively weak spin coupling interactions (compared with the bonding case), and usually possess the open-shell (OS) ground state (singlet versus triplet (T)), depending on the degree and mode of the weak coupling between the radicals. − Comparing with π-radicals, σ-radicals are formed by the elimination of an electron from σ-bonding orbitals, which are characterized by the partially broken and elongated σ C–C and/or σ C–H bonds. , In fact, these suspended sp 3 -like C σ-radicals in the cores have a large bonding tendency (bent bonding mode), but the surrounding backbones inhibit them from forming the σ-chemical bonds of traditional interest, thus leading to σ-radical characters at different C sites within the centers . It is natural to consider one interesting question: if a NV center containing the C radicals can exhibit the ferromagnetic/FM or antiferromagnetic/AFM spin coupling interactions.…”

“…22−24 Comparing with π-radicals, σ-radicals are formed by the elimination of an electron from σ-bonding orbitals, which are characterized by the partially broken and elongated σ C−C and/or σ C−H bonds. 25,26 In fact, these suspended sp 3 -like C σ-radicals in the cores have a large bonding tendency (bent bonding mode), but the surrounding backbones inhibit them from forming the σ-chemical bonds of traditional interest, thus leading to σradical characters at different C sites within the centers. 2 It is natural to consider one interesting question: if a NV center containing the C radicals can exhibit the ferromagnetic/FM or antiferromagnetic/AFM spin coupling interactions.…”