Addition reaction of alkyl radical to C₆₀ fullerene: Density functional theory study

Abstract

Abstract:Functionalized fullerenes are known as a high-performance molecule. In this study, the alkyl-functionalized fullerenes (denoted by R-C 60 ) have been investigated by means of density functional theory (DFT) method to elucidate the effects of functionalization on the electronic states of fullerene. Also, the reaction mechanism of alkyl radical with C 60 was investigated. The methyl, ethyl, propyl and butyl radicals (denoted by n=1-4, where n means number of carbon atoms in alkyl radical) were examined as alkyl radicals. The DFT calculation showed that the alkyl radical binds to the carbon atom of C 60 in the on-top site, and a strong C-C single bond was formed. The binding energies of alkyl radicals to C 60 were distributed in the ranges 31.8-35.1 kcal mol -1 at the CAM-B3LYP/6-311G(d,p) level. It was found that the activation barrier exists before the alkyl addition: the barrier heights were calculated to be 2.1-2.8 kcal mol -1 . The electronic states of R-C 60 complex were discussed on the basis of theoretical results.

Impact of Conjugation and Hyperconjugation on the Radical Stability of Allylic and Benzylic Systems: A Theoretical Study

“…Resonantly stabilized free radicals such as allyl and benzyl radicals, are ubiquitous in many chemical environments and have been detected or implicated as key intermediates in flames, , plasmas, , and in interstellar space. − These transient species are known to participate in a wide variety of chemical reactions including polymerizations, − combustions, ,− organic syntheses, , and in biological and environmental processes . For example, benzyl radicals and their derivatives have shown to be essential intermediates in the oxidation of toluene and methylbenzenes, ,, and are implicated in the formation of polycyclic aromatic hydrocarbons (PAHs) in combustion reactions and in the atmospheric processes of earth and other planets. ,− Likewise, allylic radicals play specific roles in organic chemistry, including halogenation chemistry, − addition chemistry to fullerene structures, , and in polymerizations involving multiallyl monomers. , Furthermore, allyl and benzyl radicals have allowed a simple framework to comprehend the underlying physical organic concepts governing the stability and reactivity of these compounds, especially concerning the concept of resonance and aromaticity.…”

Effect of curvature on the activation energy of monomethylation of carbon belts: a DFT study

“…The addition of the methyl radical (Me), the smallest alkyl radical, is a fundamental chemical reaction; the details of its reaction with PAHs have been investigated both experimentally and theoretically. [18][19][20][21][22][23] Me readily attaches to the graphene surface at temperatures as low as 100 K. 20,21) Theoretical studies have shown that the addition proceeds via one transition state (TS). 22,23) The E act of monomethylation on graphene is approximately five times higher (14 kcal•mol −1 ) than that on C 60 .…”

“…[18][19][20][21][22][23] Me readily attaches to the graphene surface at temperatures as low as 100 K. 20,21) Theoretical studies have shown that the addition proceeds via one transition state (TS). 22,23) The E act of monomethylation on graphene is approximately five times higher (14 kcal•mol −1 ) than that on C 60 . This difference is related to the changes in the structure and electron configuration of the Me binding site and its surroundings.…”

“…Radical addition drastically alters the structure around the carbon atom C 0 at the binding site. [22][23][24] C 0 moves outward from its original position and is locally deformed into a pyramidal configuration. The structures of the TS of the CB(n) methylation [denoted as TS(n)] are shown in Figs.…”

“…24) The R(C 0 -C Me ) of spherical C 60 fullerene and graphene flake are 2.424 and 2.131 Å, respectively. 22,23) The binding site C 0 moved outside the CB(n) surface in both TS(n) and PD(n), resulting in pyramidal structures. Δf increased as κ increased [Fig.…”