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The isolated pentagon rule (IPR) is now widely accepted as a general rule for determining the stability of all-carbon fullerene cages composed of hexagons and pentagons. Fullerenes that violate this rule have been deemed too reactive to be synthesized. The stabilization of non-IPR endohedral fullerenes depends on charge transfer from the encapsulated metal clusters (endoclusters) to fullerene cages, the electronic properties of empty all-carbon cages, the matching size and geometries of fullerene and endocluster, as well as the strong coordination of the metal ions to fused pentagons. The stability of non-IPR exohedral fullerenes can be rationalized primarily by both the 'strain-relief' and 'local-aromaticity' principles. This Review focuses on recent work on stabilization of non-IPR fullerenes, including theoretical and empirical principles, experimental methods, and molecular structures of fused-pentagon fullerenes characterized so far. The special chemical properties of non-IPR fullerenes that distinguish them from IPR-satisfying ones are also emphasized. [ABSTRACT FROM AUTHOR]

The title compound, [CuI(C11H10N2S2)] n, is built around centrosymmetric dinuclear Cu2I2 cores, each of which is linked to four neighboring Cu2I2 units via flexible dithioether ligands, viz. 4,4′-(methylenedithio)dipyridine, to form a two-dimensional grid containing rhombus-shaped cavities with diagonal distances of ca 15 and 22 Å. Two of these networks interpenetrate in a woven fashion, and the resulting structure does not possess any open channels or cavities. Each Cu atom is in a distorted tetrahedral coordination environment. [ABSTRACT FROM AUTHOR]

C78 is one of the most widely investigated higher fullerenes. Among its huge isomer family, only one non-IPA (IPR = isolated pentagon ring) cage, the C2-symmetric #22010C78, was previously stabilized by endohedral derivatization. Here we report a new C1-symmetric non-IPR hollow isomer, #23863C78, which was captured as #23863C78 Cl8 and then subjected to a regioselective substitution reaction with benzyl hydroperoxide to form #23863C78(OOCH2C6H5)Cl7. The structural connectivity of #23863C78, which contains a pair of fused pentagons, was confirmed by single-crystal X-ray diffraction analysis of the #23863C78(OOCH2C6H5)Cl7 molecule, which shares the same fullerene core with #23863C78Cl8 support for the structure is provided by comparable IR measurements and computation. Theoretical studies suggest that the differences in C-Cl bond length, intermediate stability, and steric effects of the involved molecules account for the chemical regioselectivity of the substitution reaction. [ABSTRACT FROM AUTHOR]

Two monoxides of typical smaller chlorofullerenes, #271C50Cl10O and #913C56Cl10O, featured with double-fused-pentagons, were synthesized to demonstrate further regioselective functionalization of non-IPR (IPR = isolated pentagon rule) chlorofullerenes. Both non-IPR chlorofullerene oxides exhibit an epoxy structure at the ortho-site of fused pentagons. In terms of the geometrical analysis and theoretical calculations, the principles for regioselective epoxy oxidation of non-IPR chlorofullerenes are revealed to follow both "fused-pentagon ortho-site" and "olefinic bond" rules, which are valuable for prediction of oxidation of non-IPR chlorofullerenes. [ABSTRACT FROM AUTHOR]