This paper presents sp 2 nanocarbons as a new class of topochemical species from the insight of the computational study of peculiar properties that accompany the formation of different composite, at least, one member of that is a sp 2 nanocarbon. The composites, which are resulted from either the “double-(C–C)-bond” reactions between two sp 2 nanocarbons or the “atom-(C–C)-bond” reactions, concerned with a monatomic species deposition on the nanocarbons, manifest clearly seen properties that can be addressed to the action of either internal or external topology. The internal topology is attributed to the inherited properties of each nanocarbon while the external topology is related to external factors that drastically influence the chemical reactions involving nanocarbons.