The pure I(h) isomer of Sc3N@C80 was allowed to react with N-triphenylmethyl-5-oxazolidinone via the corresponding azomethine ylide. The reaction results in the formation of two monoadducts; one (1b) is the kinetic product, and the other (1a) is thermodynamically more stable. Small amounts of the bisadducts were also formed. The structure of the thermodynamic monoadduct 1a was shown conclusively by NMR spectroscopy and X-ray crystallography to result from addition across the 5,6-ring junction. The kinetic product 1b was demonstrated to be the 6,6-ring juncture adduct on the basis of NMR experiments and X-ray crystallography. In refluxing chlorobenzene pure 1b was converted to the more thermodynamically stable 1a isomer. These N-tritylpyrrolidino derivatives are potentially useful precursor compounds for further derivatization for various applications.

In this paper we report enhanced reactivity of the D(5h) isomers in comparison with the more common I(h) isomers of Sc(3)N@C(80) and Lu(3)N@C(80) toward Diels-Alder and 1,3-dipolar tritylazomethine ylide cycloaddition reactions. Also, the structure of the D(5h) isomer of Sc(3)N@C(80) has been determined through single-crystal X-ray diffraction on D(5h)-Sc(3)N@C(80).Ni(OEP).2benzene (OEP = octaethylporphyrin). The Sc(3)N portion of D(5h)-Sc(3)N@C(80) is strictly planar, but the plane of these four atoms is tipped out of the noncrystallographic, horizontal mirror plane of the fullerene by 30 degrees . The combination of short bond length and high degree of pyramidization for the central carbon atoms of the pyracylene sites situated along a belt that is perpendicular to the C(5) axis suggests that these are the sites of greatest reactivity in the D(5h) isomer of Sc(3)N@C(80). Consistent with the observation of higher reactivity observed for the D(5h) isomers, cyclic voltammetry and molecular orbital (MO) calculations demonstrate that the D(5h) isomers have slightly smaller energy gaps than those of the I(h) isomers. The first mono- and bis-adducts of D(5h) Sc(3)N@C(80) have been synthesized via 1,3-dipolar cycloaddition of tritylazomethine ylide. The NMR spectrum for the monoadduct 2b is consistent with reaction at the 6,6-ring juncture in the pyracylene unit of the D(5h) Sc(3)N@C(80) cage and is the thermodynamically stable isomer. On the other hand, monoadduct 2a undergoes thermal conversion to other isomeric monoadducts, and three possible structures are proposed.

In this paper we report a regioselective Bingel−Hirsch reaction of Sc3N@C78 yielding a single mono- and a dominate bis-ethyl malonate derivative for the first time. The C s -symmetric monoadduct 1 and C 2 v -symmetric bisadduct 2 were isolated by HPLC and characterized by MS, UV−vis, and NMR spectroscopy. The symmetric bisadduct 2 clearly demonstrate the remarkable regioselectivity control exerted by the encapsulated Sc3N cluster. We have employed a LUMO electron density surface computational approach to predict multiadduct docking sites on the ellipsoidal fullerene cage surface.