Theoretical Study of the Possibility of Functionalization of C20 Fullerene with the Simplest Ketene CH2CO

Resumo

The functionalization is known as a structural modification procedure of fullerenes and carbon nanotubes. This method improves the chemical and physical properties, such as reactivity and solubility. This paper intends to theoretically describe the possibility of functionalization of C₂₀ fullerene with the simplest ketene CH₂CO. In the first step, two possible [2+2] and [4+2] cycloaddition reactions between C₂₀ and ketene are considered and simulated theoretically. The results show that the [2+2] reaction is favorable both thermodynamically and kinetically. Also, the IRC analysis of transition states indicates that the reaction takes place via a step-wise mechanism in which a zwitterionic intermediate is generated in a rate-determining step. The solvation effect study based on the CPCM model reveals that by changing the reaction medium from nonpolar to polar, the reaction rate is increased. The NBO analysis and the calculation of global electron density transfer (GEDT) indicate that the reaction involves polar transition states. The calculations of the thermodynamic and kinetic parameters of the [2+2] cycloaddition reaction of bowl C₂₀ with ketene show that this reaction is unfavorable.