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Relative populations of four IPR (isolated-pentagon-rule) isomers of Eu@C82 are computed using the Gibbs energy based on characteristics from density functional theory calculations (M06-2X/6-31G∗∼SDD entropy term, M06-2X/6-31+G∗∼SDD or B2PLYPD/6-31G∗∼SDD energetics). Only the species observed by now also show significant calculated populations. A role of solubility in different solvents and/or composition of the arc electrodes could explain variability in the observed populations.

The cyclic water-trimer encapsulations into D 2 (22)- C 84 fullerene are evaluated. The encapsulation energy is computed at the M06-2X/6-31++G∗∗ level and it is found that the trimer storage in C 84 yields the potential-energy gain of 10.4 kcal/mol. The encapsulated trimer can have two different forms, either the conformation known with the free gas-phase water trimer or the arrangement with the three non-hydrogen bonded H atoms on the same side of the O-O-O plane. The latter endohedral isomer is lower in the potential energy by 0.071 kcal/mol and forms about 57% of their equilibrium mixture at room temperature.

The very recently prepared clusterfullerene Y2C2@ C 1 (1660)-C108 is computed and the observed structural features are confirmed, including the quasi-linear arrangement of the encapsulate and its near-triple CC bond. Its stability is explained by sizeable encapsulation energy. The endohedral stability is evaluated at both DFT and MP2 levels.

A dynamic motion of the encaged metal in the D3h cage is proposed for Yb@C74(II) according its NMR spectrum. In addition, the calculated NMR spectra of D3h-C74 and Yb@C74 with a D3h cage and the static metal are presented. By comparing Yb@C74’s dynamic and static NMR spectra, the dynamic metal’s effect on the NMR behavior of the metallofullerene is discussed.

The cation and anion of Y@C82 were prepared by controlled potential electrolysis, and their stabilities were investigated by spectroscopic methods. The anion is found to be much more stable than the cation under an air atmosphere. The cage structure of Y@C82 was determined by observing the 13C NMR spectrum of the stable diamagnetic anion. It is confirmed that Y@C82 has C2v symmetry.

The redox property of Sc 3 @C 82 is investigated by using disilirane as a chemical probe. The redox potential of Sc 3 @C 82 in o -dichlorobenzene shows a high reactivity attributable to its high electron-accepting and -donating ability. No ESR signal is observed at room temperature for Sc 3 @C 82 in the presence of pyridine, indicating formation of the diamagnetic Sc 3 @C 82 anion. The diamagnetic Sc 3 @C 82 anion is also prepared electrochemically in 1,2-dichlorobenzene.

Density functional calculations are carried out for the La2@C80 derivatives to investigate whether the motion of metals encapsulated inside fullerenes is controlled by exohedral addition. It is shown that the three-dimensional random motion of two La atoms in La2@C80 can be restricted to the circular motion in a plane by attaching electron-donating molecules on the outer surface of the C80 cage. It is expected that the two-dimensional circular motion will help to induce a unique electronic or magnetic field.

A stable diamagnetic mono-anion of the major isomer of Pr@C 82 (Pr@C 82 –A) was electrochemically prepared and isolated to determine the symmetry of its carbon cage. By measurement of the 13 C NMR spectrum of the anion, Pr@C 82 –A is found to have C 2v symmetry.

The structure of La2@C80 is studied by La K-edge XAFS from 40 to 295 K. The distances between the La atom and the first nearest C atoms have been determined to be 2.42(1) A at 40 K and 2.44(2) A at 295 K, and those between the La atom and the second nearest C atoms to be 2.97(2) A at 40 K and 2.98(3) A at 295 K. The La–La distance has been determined to be 3.90(1) A at 40 K and 3.88(2) A at 295 K. The temperature dependence of the mean-square displacement of La–C is also studied to get an insight into the dynamical behavior of two La atoms in the C80 cage.

The second isomer of Pr@C82 (Pr@C82-II) has been isolated by a two-step HPLC method, separately from the known major isomer (Pr@C82-I). Visible and near-IR absorption spectra, as well as cyclic and differential pulse voltammograms show that the characteristic features of Pr@C82-II are significantly different from those of Pr@C82-I. The absorption peaks of Pr@C82-II have blue-shifts and the redox potentials have negative shifts, relative to those of Pr@C82-I. Chemical derivatization of both isomers with disilirane have also been achieved.

By using density functional theory calculations, it is found that the strongest interaction between NH 3 and single-wall carbon nanotubes (SWNTs) is via its one H atom. The adsorption of NH 3 on the metallic (7, 7) SWNT turns out to be slightly stronger than that on the semiconducting (13, 0) SWNT.

In order to provide insight into the motion of metal atoms in endohedral dimetallofullerenes, Sc 2 @C 84 and La 2 @C 80 are investigated as typical examples by use of ab initio molecular orbital and nonlocal density functional methods. It is suggested that the two Sc atoms can oscillate with considerable amplitude while the two La atoms can circulate inside the fullerene cage with small barriers of ≈ 5 cal/mol. It is expected that such metal motions will lead to interesting electronic and magnetic properties.

The structures, energies and electronic properties of seven C 80 fullerene isomers and of La 2 @C 80 are investigated by means of semi-empirical and ab initio calculations. Unlike recent theoretical studies, it is found that the most stable C 80 isomers have D 2 and D 5 symmetries while the I h isomer is most unstable. Upon endohedral doping by two La atoms, however, the I h isomer is most highly stabilized thermodynamically and kinetically with an electronic structure of (La 3+ ) 2 C 80 6− . The I h cage structure and electronic properties predicted for La 2 @C 80 agree with experimental data.

In an attempt to reinforce our recent experiments on silylene-oxygen adducts, the structure and kinetic stability of silanone oxide (H 2 SiOO) in the singlet state have been investigated at several levels of theory. It is found that silanone oxide has a non-planar, pyramidal structure and undergoes rapid cyclization to siladioxirane, unlike the corresponding carbon compound (H 2 COO).