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The addition reaction of C60 with silylene 1, a silicon analog of carbene, yielded the corresponding bis-adduct 3. The structure of 3 was determined by single-crystal X-ray structure analysis, representing the first example of a crystal structure of a silirane (silacyclopropane) derivative of fullerenes. Electrochemical measurements confirmed that the redox potentials of 3 are shifted cathodically compared to those of the parent mono-adduct 2. Density functional theory (DFT) calculations provided the basis for the electronic properties of compound 3.

Endohedral metallofullerenes have excellent redox properties, which can be used to vary their reactivity to certain classes of molecules, such as alkyl halides. In this study, the thermal reaction of the La@C2v-C82 anion with benzyl bromide derivatives 1 at 110 °C afforded single-bonded adducts 2–5 with high regioselectivity. The products were characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and visible–near infrared spectroscopy. The reaction of La@C2v-C82 with alkyl halides using the same conditions showed no consumption of La@C2v-C82, indicating that the reactivity of La@C2v-C82 toward alkyl halides was effectively increased by one-electron reduction. Single-crystal X-ray diffraction analysis of the single-bonded adduct 3a revealed the addition site of the p-methoxybenzyl group on La@C2v-C82. Theoretical calculations indicated that the addition site carbons in neutral La@C2v-C82 have high spin density, whereas those in the La@C2v-C82 anion do not have high charge densities. Thus, the reaction is believed to occur via electron transfer, followed by the radical coupling of La@C2v-C82 and benzyl radicals, rather than by bimolecular nucleophilic substitution reaction of La@C2v-C82 anion with 1.

The structure and energetics of the clusterfullerene La2C2@D5(450)-C100 are calculated at the B3LYP/6-31G*∼SDD level (including counterpoise correction for the basis set superposition error), and the observed features are confirmed. Its stability is explained by substantial energy gain connected with the encapsulation, viz. 140 kcal/mol per atom of the encapsulate, actually higher than previously found for comparable systems.

The recently synthetically prepared endohedral CH4@C60 was characterized here using calculations—namely its structure, energetics, thermodynamics, and vibrational spectrum. The calculations were carried out with DFT (density-functional theory) methods, namely by the DFT M06-2X functional and MP2, as well as B2PLYPD advanced correlated, treatments with the standard 6-31++G** and 6-311++G** basis sets, corrected for the basis set superposition error evaluated using the approximative Boys–Bernardi counterpoise method. The symmetry of the endohedral obtained in the geometry optimizations was tetrahedral T. The energetics of CH4 encapsulation into C60 was attractive (i.e., with a negative encapsulation-energy term), producing a substantial energy gain of −13.94 kcal/mol at the most advanced computational level, B2PLYPD/6-311++G**. The encapsulation equilibrium constants for CH4@C60 were somewhat higher than previously found with the CO@C60 system. For example at 500 K, the encapsulation equilibrium constant for CH4@C60 had a value one order of magnitude larger than for CO@C60. The encapsulation thermodynamic characteristics suggest that high-pressure and high-temperature synthesis could in principle also be possible for CH4@C60.

Relative equilibrium populations of the five lowest-energy isolated-pentagon-rule (IPR) isomeric structures of Pr@C82 under high-temperature fullerene synthesis conditions were calculated with the Gibbs energy terms based on molecular characteristics derived using density functional theory (DFT) treatments (B3LYP/6-31+G*∼SDD energetics and B3LYP/6-31G*∼SDD entropy). Two leading isomers were identified, major Pr@C2v;9-C82 and minor Pr@Cs;6-C82. The calculated isomeric relative equilibrium populations agreed with observations.

This report deals with the quantum-chemical evaluation of the energetics and thermodynamics of the simultaneous encapsulation of HF and H2O by the IPR (isolated pentagon rule) C70 fullerene cage, yielding H2O·HF@C70 species which were synthesized and characterized recently, thus further expanding the family of fullerene endohedrals with non-metallic encapsulates. The structures were optimized at the DFT (density functional theory) M06-2X/6-31++G** level. The encapsulation energetics were further refined by the advanced B2PLYPD/6-31++G** and B2PLYPD/6-311++G** methods. After enhancement of the B2PLYPD/6-311++G** encapsulation energy for the BSSE and steric corrections, the encapsulation energy gain was obtained, as 26 kcal/mol. The equilibrium encapsulation thermodynamics were described using the M06-2X/6-31++G** partition functions. The results correspond to our previous evaluations for the water dimer encapsulation by C84 cages.

Compositing all-carbon materials with distinct dimensions and structures has demonstrated the great potential to bring synergistic promotion to individual components for the electrocatalytic activity of oxygen reduction reaction (ORR). Fullerene-derived porous carbon fibers (FPCFs) offer unique one-dimensional (1D) nanostructures with abundant defects and a large specific surface area while graphene features two-dimensional (2D) nanostructures with fast electron transfer. Both carbon materials are promising alternatives to Pt-based electrocatalysts for ORR. Herein, a novel hierarchical composite (FPCFs@rGO) composed of FPCFs and reduced graphene oxide (rGO) is constructed by sonication-assisted mixing and high-temperature pyrolysis. When tested as an electrocatalyst for ORR, the 1D/2D FPCFs@rGO composite presents significantly enhanced performance compared to each individual component, indicating an eminent synergistic effect between FPCFs and rGO. The improved ORR performance of FPCFs@rGO is attributed to the unique hierarchical structure with abundant structural defects, a large specific surface area, and high porosity.

Under photoirradiation, Sc3N@Ih-C80 reacted readily with disilirane 1, silirane 4, and digermirane 7 to afford the corresponding 1:1 adducts, whereas Sc3N@D5h-C80 was recovered without producing those adducts. Based on these results, we described a novel method for the exclusive separation of Ih and D5h isomers of Sc3N@C80. The method includes three procedures: selective derivatization of Sc3N@Ih-C80 using 1, 4, and 7, facile HPLC separation of pristine Sc3N@D5h-C80 and Sc3N@Ih-C80 derivatives, and thermolysis of Sc3N@Ih-C80 derivatives to collect pristine Sc3N@Ih-C80. In addition, laser flash photolysis experiments were conducted to elucidate the reaction mechanism. Decay of the transient absorption of 3Sc3N@Ih-C80 * was observed to be enhanced in the presence of 1, indicating the quenching process. When Sc3N@D5h-C80 was used, the transient absorption was much less intensive. Therefore, the quenching of 3Sc3N@D5h-C80 * by 1 could not be confirmed. Furthermore, we applied time-dependent density functional theory (TD-DFT) calculations of the photoexcited states of Sc3N@C80 to obtain insights into the reaction mechanism. [ABSTRACT FROM AUTHOR]