Electronic conjugation of carbon atoms in spherical and cylindrical molecules

An examination of the peculiarities of ρ-electron conjugation of carbon atoms in spherical (fullerenes) and cylindrical (single-walled carbon nanotubes) molecular systems was performed using an analysis of topological isomerism of [N]-annulenes. It was demonstrated that a ρ-electron conjugation has a stabilizing effect with respect to a π-electron conjugation; however, the value of this effect is minor. A non-uniform distribution of electron density in the molecules leads to a considerable alternation of C-C bond lengths and the absence of ring currents in external magnetic field. All the conclusions regarding the peculiarities of ρ-electron conjugation were confirmed by the model and by calculations for the real molecular systems using an ab initio Hartree-Fock method in the 3-21G basis and comparison of its results with experimental data.