Substructural Approach for Assessing the Stability of Higher Fullerenes

This review describes the most significant published results devoted to the study of the nature of the higher fullerenes stability, revealing of correlations between the structural features of higher fullerene molecules and the possibility of their producing. A formalization of the substructure approach to assessing the stability of higher fullerenes is proposed, which is based on a detailed analysis of the main structural features of fullerene molecules. The developed substructure approach, together with the stability of the substructures constituting the fullerene molecule, helps to understand deeper the features of the electronic structure of fullerenes

Radical IPR Fullerenes C₇₄ (D_3h) and C₇₆ (T_d): Dimer, Trimer, etc. Experiments and Theory

Analyses based on molecular modeling, bonds distribution, and subsequent quantum-chemical calculations of open-shell fullerenes C₇₄ (D_3h) and C₇₆ (T_d) as initial representatives of polymers have shown that the binding of molecules is most probable with participation of <b><i>c–c</i></b> atoms for fullerene C₇₄ (D_3h) and <b><i>b–c</i></b> and <b><i>c–c</i></b> atoms for fullerene C₇₆ (T_d). Open-shell triplet configurations of dimer molecules remains more favorable, including trimers, tetramers, and pentamers of C₇₄ (D_3h) having a chain structure. Analysis of the published experimental data demonstrates the reconcilable picture of this IPR C₇₄ (D_3h) radical fullerene “life”

Stabilization of IPR open-shell fullerenes C₇₄ (D_3h) and C₇₆ (T_d) in radical addition reactions

<p>The analysis of previously experimentally obtained and characterized by X-ray perfluoralkyl derivatives C₇₄(D_3h)(CF₃)₁₂ and C₇₆(T_d)(CF₃)₁₂ have shown for the first time that the most feasible positions of addends are phenalenyl-radical substructures and/or hexagons with delocalized pi-bonds, that lead to stabilization of these molecules. The most probable addition positions of H^• and CF₃^• radicals to the «missing» fullerenes С₇₄ (D_3h) and С₇₆ (T_d) are revealed on the basis of developed approach of molecular modeling followed by DFT calculations. Radical addition reactions seem to be useful for stabilization of open-shell fullerenes.</p

Molecular structures of the open-shell IPR isomers of fullerene C₉₀

<p>Fifteen open-shell isomers off the forty six IPR isomers of fullerene C₉₀ were found and investigated: 5 (C_s), 7 (C₁), 9 (C₁), 10 (C_s), 11 (C₁), 20 (C₁), 21 (C₁), 22 (C₁), 23 (C₂), 24 (C₁), 25 (C_2v), 41 (C₂), 42 (C₂), 43 (C₂), and 44 (C₂). According to developed by us approach the positions of single, double, and delocalized π-bonds in the molecules of these isomers are shown for the first time. The obtained results of electronic and geometrical structures are fully supported by DFT method with the B3LYP functional at the 6-31G and 6-31G* levels. Molecules of these open-shell isomers contain different radical substructures (mainly the phenalenyl-radical substructures), they should be unstable and could not be obtained as empty molecules. Nevertheless, there is a possibility of obtaining them in polymeric forms or as endohedral or exohedral derivatives.</p