Within the wr-orbital axis vector theory, the total rehybridization required for closure of the fullerenes is approximately conserved. This result allows the development of a structure-based index of strain in the fullerenes, and it is estimated that about 80 percent of the heat of formation of the carbon atoms in C60 may be attributed to a combination of v strain and steric inhibition of resonance. Application of this analysis to the geometries of structurally characterized organometallic derivatives of C60 and C70 shows that the reactivity exhibited by the fullerenes may be attributed to the relief of a combination of local and global strain energy. C60 is of ambiguous aromatic character with anomalous magnetic properties but with the reactivity of a continuous aromatic molecule, moderated only by the tremendous strain inherent in the spheroidal structure.

https://science.sciencemag.org/content/sci/261/5128/1545.full.pdf

Chemistry of the fullerenes: the manifestation of strain in a class of continuous aromatic molecules.

A method to grow carbon microtubules with fullerene structure (buckytubes) has been identified. The method consists of the catalytic decomposition of acetylene over iron particles at 700 °C. Carbon microtubules of up to 50 μm in length are synthesized by this method. Electron diffraction and high resolution electron microscopy studies demonstrate that the structure of these microtubules corresponds to the helical structure recently reported by S. Iijima, Nature 354, 56(1991), prepared using an arc‐discharge evaporation method.

Catalytic growth of carbon microtubules with fullerene structure

The field of cluster research can trace its origins back to the mid-nineteenth century when early studies of colloids, aerosols, and nucleation phenomena were reported. The field underwent a resurgence of interest several decades ago when well-defined clusters were observed in supersonic expansions that could be investigated using mass spectrometers. The advent of the laser provided a new dimension, enabling detailed spectroscopic observations through the probing of systems of varying size and degree of solvation. Modern interest derives from recognition that interrogating clusters provides a way of studying the energetics and dynamics of intermediate states of matter as cluster systems evolve from the gas toward the condensed state. Herein, we endeavor to highlight some of the significant advances which have been made during the past several decades that have led to a nearly explosive growth of interest in the field of cluster science. Finally, we conclude that the field will continue to expand through i...

Clusters: Structure, Energetics, and Dynamics of Intermediate States of Matter

Initially envisaged as rather unreactive, aromatic-like molecules, the fullerenes instead undergo a wide variety of reactions characteristic of alkenes. The many derivatives of C60, and the few of C70, that have now been reported offer new directions for organic chemistry.

The Chemistry of Fullerenes

The covalent functionalization of C 60 has developed vigorously over the past 5 years. Several methods are now available for the formation of C 60 monoadducts. Regioselective formation of multiple adducts has allowed study of the changes in chemical and physical properties that occur when the conjugated fullerene chromophore is reduced during an increase in functionalization. The systematic development of covalent fullerene chemistry provides an unprecedented diversity of tailor-made three-dimensional building blocks for technologically interesting materials.

http://science.sciencemag.org/content/sci/271/5247/317.full.pdf

Covalent Fullerene Chemistry

The toluene extract of the fluffy carbon material produced by resistive heating of graphite contains a variety of molecules larger than C(60) and C(70) in a total amount of 3 to 4% by weight. Repeated chromatography of this material on neutral alumina has led to the isolation of stable solid samples of C(76), C(84), C(90), and C(94). The characterization, which includes mass spectrometry, (13)C nuclear magnetic resonance, electronic absorption (ultraviolet/visible) and vibrational (infrared) spectroscopy identifies these all-carbon molecules as higher fullerenes. In addition, C(70)O, a stable oxide, has been isolated that is structurally and electronically closely related to D5h-C(70). This compound forms during the resistive heating process and probably has an oxygen atom inserted between two carbon atoms on the convex external surface of the C(70) skeleton.

https://science.sciencemag.org/content/sci/252/5005/548.full.pdf

The Higher Fullerenes: Isolation and Characterization of C76, C84, C90, C94, and C70O, an Oxide of D5h-C70

The average kinetic-energy release is measured for the evaporation of CsI and (CsI${)}_{2}$ molecules from sputtered Cs(CsI${)}_{\mathrm{n}}^{+}$ clusters (n=2--17) in two different time windows. Size and temporal (temperature) dependence of the average kinetic-energy release (KER) is found to be in reasonable agreement with the predictions of the evaporative ensemble model, except for evaporation processes involving the cluster with magic number n=13. Agreement can be obtained for the latter if the assumption of the independence of the heat of evaporation on the cluster size in the model is removed.

Size and temporal dependence of the average kinetic-energy release during the evaporation of sputtered Cs(CsI)n+ clusters.

Kinetic energy release distribution and the mechanism for evaporation of one and two CsI molecules from sputtered Cs(CsI)n+ clusters

The metastable decomposition of sputtered Cs(CsI){sub n}{sup +} clusters of 1 {<=} n {<=} 17 is investigated in 2 different time windows by use of a double-focusing sector field mass spectrometer (reversed geometry). Cs (CsI){sub n}{sup +} clusters are found to decompose mainly by evaporation of one or two CsI molecules in their time windows. Comparison of the evaporation probability with the evaporation energy predicted from the polarizable-ion model suggests that the 2 evaporation channels (the CsI monomer and dimer evaporation) are parallel and adiabatic with no reverse activation energy.

Dilip K. Sensharma

Papers

The Higher Fullerenes: Isolation and Characterization of C76, C84, C90, C94, and C70O, an Oxide of D5h-C70

Size and temporal dependence of the average kinetic-energy release during the evaporation of sputtered Cs(CsI)n+ clusters.

Kinetic energy release distribution and the mechanism for evaporation of one and two CsI molecules from sputtered Cs(CsI)n+ clusters

Unimolecular decomposition of sputtered cesium-cesium iodide (Cs(CsI)n+) clusters: stabilities and evaporation energetics

Relative stability, possible structural formulas, and unimolecular and collision-induced dissociation of negatively charged monoiodide silver clusters