A Computational Study of the Intermolecular [2+2+2] Cycloaddition of Acetylene and C₆₀ Catalyzed by Wilkinson's Catalyst

Abstract

The functionalization of fullerenes helps to modulate their electronic and physicochemical properties, generating fullerene derivatives with promising features for practical applications. Herein, DFT is used to explore the attachment of a cyclohexadiene ring to C through a rhodium-catalyzed intermolecular [2+2+2] cycloaddition of C and acetylene. All potential reaction paths are analyzed and it can be concluded that the [2+2+2] cycloaddition of C and two acetylene molecules catalyzed by [RhCl(PPh ) ], yielding a cyclohexadiene ring fused to a [6,6] bond of C , is energetically feasible.

Expeditious Preparation of Open‐Cage Fullerenes by Rhodium(I)‐Catalyzed [2+2+2] Cycloaddition of Diynes and C60: An Experimental and Theoretical Study

“…Finally, we also analyzed the possible formation of a rhodanorbornene complex through a rhodium‐mediated [4+2] cycloaddition, but all our attempts to find this intermediate failed. It is worth noting that with the Wilkinson catalyst, the same reaction mechanism was found, except for the insertion step, which leads in this case to a rhodacycloheptadiene intermediate analogous to A5′ (Schore's mechanism) without formation of a rhodabicyclo[3.2.0]heptadiene intermediate A4 …”

“…1D and 2D NMR spectroscopic experiments wereu sed to ascertain the structure of the product formed. Both the 1 Ha nd 13 CNMR spectra show that the new compound has C s rather than C 2v symmetry,t he latter resulting from acycloaddition reaction at the [6,6] bond. Acareful analysis of the NMR data revealed an unanticipated but desirable outcome: the compound formed was not the expected cycloadduct, but rather the corresponding open-cage bis(fulleroid) structure ( Figure 1).…”

“…The 2D spectrumd isplays at wo-bond correlation between the protons of the methyl group and the C(sp 3 ) at 43.4 ppm and at hree-bond correlation between the same protons and three C(sp 2 )q uaternary carbon atoms (134.9, 137.4, and1 50.2 ppm), proving the accuracy of our earlier observation. The assignment of the most characteristic signals in the 1 Ha nd 13 CNMR spectra is shown in Figure 1.…”

“…It is worth noting that with the Wilkinson catalyst, the same reaction mechanism wasf ound, except for the insertion step, which leads in this case to ar hodacycloheptadiene intermediate analogous to A5' (Schore's mechanism) [19] without formation of arhodabicyclo[3.2.0]heptadiene intermediate A4. [13] In summary,t he [2+ +2+ +2] cycloaddition that produces A5 from A0 has an energetic span [20] betweent he turnover frequency( TOF) determining intermediate (TDI, A1)a nd TOF determining transition state (TDTS, TS A1A2)o f2 5.7 kcal mol À1 . This is in accordance with most [2+ +2+ +2] cycloadditions in which the rate-determining step (rds) is the oxidative coupling.…”

Theoretical study of bis-adduct fulleropyrrolidines isomers

“…[5][6][7] Particularly, fulleropyrrolidines synthesis leads generally to a complicate mixture of several adducts in their different isomers. [8][9][10] Compared to classic semiconductors, however, the bi functionalization of fullerenes has highlighted the crucial role that allotropic forms of carbon could play in optimizing photovoltaic cell efficiency. 2 This is due to the various isomers that a bi-addition (8 isomers) could generate.…”