ODD-ELECTRONS APPROACH TO COVALENT CHEMISTRY AND MAGNETISM OF SINGLE-WALL CARBON NANOTUBES AND GRAPHENE

The covalent chemistry and magnetism of single-walled carbon nanotubes and graphene is considered on the basis of peculiarities of odd electron interaction in the studied nanocarbons. The term indicates that the number of valence electrons of each nanocarbon atom is larger by one than the number of chemical bonds it forms. The main issue of the odd-electron concept concerns a partly radical character of the species which is resulted from the presence of effectively unpaired electrons that constitute a part of odd electrons excluded from the covalent bonding. The total number of effectively unpaired electrons N _D and its fraction on each atom N _DA are suggested as quantifiers of molecular atomic susceptibility and atomic chemical susceptibility, respectively, thus highlighting targets that are the most favorable for addition reactions of any type. The approach is illustrated for two families of carbon nanotubes involving fragments of arm-chair (n,n) and zigzag (m,0) single-walled nanotubes different by the length and end structure, as well as by a set of nanographenes and silicene. Simultaneously, the odd-electron concept lays the foundation for exhibiting the magnetism when nanostructuring of the species provides a significant weakening of the electron interaction so that exchange integrals, describing exchange electron interaction, become small enough to favor magnetic ordering in the body. The suggested "scaly" nature of the phenomenon is well consistent with the latest experimental findings.