title: On the mechanism of intramolecular nitrogen-atom hopping in the carbon chain of C₆N radical: a plausible 3c-4e crossover π long-bond.
abstract: Linear isomers of C6N radical differ in the position of the nitrogen atom in the carbon chain of C6N. Reaction routes, involving intramolecular nitrogen atom insertion at varying position in the carbon chain of C6N, are analyzed for the isomerisation between linear isomers of C6N. Through an automated and systematic search performed with global reaction route mapping of the potential energy surface, thermal isomerisation pathways for C6N radical are proposed based on the computations carried out at CASSCF/aug-cc-pVTZ, and CCSD(T)/6-311++G(d,p)//B3LYP/6-311++G(d,p) levels of the theory. Notably, a high lying linear isomer, centrosymmetric with respect to the nitrogen atom, is observed to be stabilized by a unique crossover three center-four electron π long bond between the carbon atoms that are spatially separated by a nitrogen atom in a natural bond orbital. This long bond is concluded to be responsible for the predicted thermal isomerisation to be more feasible than the dissociation during the isomerisation pathway of a linear isomer of C6N.
authors.affiliation: Quantum Chemistry Group, Department of Chemistry and Centre of Advanced Studies in Chemistry, Panjab University, Chandigarh, 160014, India.
authors.forename: Gurpreet
authors.initials: G
authors.lastname: Kaur
authors.lastname: Vikas
keywords: free radicals; isomerisation; long bonding; natural bond orbital; reaction pathways