Ivan E. Kareev

Synthesis and structures of poly(perfluoroethyl)[60]fullerenes: 1,7,16,36,46,49-C60(C2F5)6 and 1,6,11,18,24,27,32,35-C60(C2F5)8

The high-temperature reaction of C60 and C2F5I produced poly(perfluoroethyl)fullerenes with unprecedented addition patterns.

X-ray structure and DFT study of C1-C60(CF3)12. A high-energy, kinetically-stable isomer prepared at 500 °C

The title compound, prepared from C60 and CF3I at 500 °C, exhibits an unusual fullerene(X)12 addition pattern that is 40 kJ mol−1 less stable than the previously reported C60(CF3)12 isomer.

Electron Donor–Acceptor Interactions in Regioselectively Synthesized exTTF2–C70(CF3)10 Dyads

The decakis(trifluoromethyl)fullerene C(1)-C(70)(CF(3))(10), in which the CF(3) groups are arranged on a para(7)-meta-para ribbon of C(6)(CF(3))(2) edge-sharing hexagons, and which has now been prepared in quantities of hundreds of milligrams, was reacted under standard Bingel-Hirsch conditions with a bis-pi-extended tetrathiafulvalene (exTTF) malonate derivative to afford a single exTTF(2)-C(70)(CF(3))(10) regioisomer in 80 % yield based on consumed starting material. The highly soluble hybrid was thoroughly characterized by using 1D (1)H, (13)C, and (19)F NMR, 2D NMR, and UV/Vis spectroscopy; matrix-assisted laser desorption ionization (MALDI) mass spectrometry; and electrochemistry. The cyclic voltammogram of the exTTF(2)-C(70)(CF(3))(10) dyad revealed an irreversible second reduction process, which is indicative of a typical retro-Bingel reaction; whereas the usual phenomenon of exTTF inverted potentials (E1ox>E2ox), resulting in a single, two-electron oxidation process, was also observed. Steady-state and time-resolved photolytic techniques demonstrated that the C(1)-C(70)(CF(3))(10) singlet excited state is subject to a rapid electron-transfer quenching. The resulting charge-separated states were identified by transient absorption spectroscopy, and radical pair lifetimes of the order of 300 ps in toluene were determined. The exTTF(2)-C(70)(CF(3))(10) dyad represents the first example of exploitation of the highly soluble trifluoromethylated fullerenes for the construction of systems able to mimic the photosynthetic process, and is therefore of interest in the search for new materials for photovoltaic applications.

Efficient Regioselective [4+2] Cycloaddition of o-Quinodimethane to C70(CF3)10

The Diels-Alder reaction of C(1)-C(70)(CF(3))(10) and 3,6-dimethoxy-1,2-quinodimethane leads regioselectively to the formation of a new cycloadduct that has been fully characterized by spectroscopic and electrochemical methods as well as by X-ray diffraction.

Unraveling the Electron Spin Resonance Pattern of Nonsymmetric Radicals with 30 Fluorine Atoms: Electron Spin Resonance and Vis−Near-Infrared Spectroelectrochemistry of the Anion Radicals and Dianions of C60(CF3)2n (2n = 2−10) Derivatives and Density Functional Theory-Assisted Assignment

The charged states of C(60)(CF(3))(2n) (2n = 2-10) derivatives have been studied by electron spin resonance (ESR) and vis-near-infrared (NIR) spectroelectrochemistry. The anion radicals and diamagnetic dianions were furthermore described by theoretical calculations. The ESR spectra of anion radicals exhibit complex patterns due to multiple CF(3) groups. Their interpretation is accomplished by DFT calculations with B3LYP functional. It is shown that calculations provide reliable results when the extended aug-cc-pCVTZ basis set is used for fluorine atoms; however, specially tailored basis sets such as EPR-III also give very similar results with only a fraction of the computational cost. Absorption spectra of the anions exhibit NIR absorption bands, whose assignment is provided by time-dependent DFT calculations.

Harnessing Electron Transfer from the Perchlorotriphenylmethide Anion to Y@C82(C2v) to Engineer an Endometallofullerene‐Based Salt

We show that electron transfer from the perchlorotriphenylmethide anion (PTM(-)) to Y@C82(C2v) is an instantaneous process, suggesting potential applications for using PTM(-) to perform redox titrations of numerous endohedral metallofullerenes. The first representative of a Y@C82-based salt containing the complex cation was prepared by treating Y@C82(C2v) with the [K(+)([18]crown-6)]PTM(-) salt. The synthesis developed involves the use of the [K(+)([18]crown-6)]PTM(-) salt as a provider of both a complex cation and an electron-donating anion that is able to reduce Y@C82 C2v). For the first time, the molar absorption coefficients for neutral and anionic forms of the pure isomer of Y@C82(C2v) were determined in organic solvents with significantly different polarities.

EPR spectrum of the Y@C82 metallofullerene isolated in solid argon matrix: hyperfine structure from EPR spectroscopy and relativistic DFT calculations

The EPR spectrum of the Y@C(82) molecules isolated in solid argon matrix was recorded for the first time at a temperature of 5 K. The isotropic hyperfine coupling constant (hfcc) A(iso) = 0.12 +/- 0.02 mT on the nucleus (89)Y as derived from the EPR spectrum is found in more than two times greater than that obtained in previous EPR measurements in liquid solutions. Comparison of the measured hfcc on a metal atom with that predicted by density-functional theory calculations (PBE/L22) indicate that relativistic method provides good agreement between experiment in solid argon and theory. Analysis of the DFT calculated dipole-dipole hf-interaction tensor and electron spin distribution in the endometallofullerenes with encaged group 3 metal atoms Sc, Y and La has been performed. It shows that spin density on the scandium atom represents the Sc d(yz) orbital lying in the symmetry plane of the C(2v) fullerene isomer and interacting with two carbon atoms located in the para-position on the fullerene hexagon. In contrast, the configuration of electron spin density on the heavier atoms, Y and La, is associated with the hybridized orbital formed by interaction of the metal d(yz) and p(y) electronic orbitals.

1,6,11,16,18,26,36,44,48,58-Decakis(trifluoromethyl)-1,6,11,16,18,26,36,44,48,58-decahydro­(C60–Ih)[5,6]fullerene benzene hemisolvate

# 2006 International Union of Crystallography All rights reserved The title compound, C70F30 0.5C6H6, which crystallizes with one half-molecule of benzene in the asymmetric unit, is one of four isomers of C60(CF3)10. The benzene molecule is disposed about a center of inversion. The fullerene molecule has an idealized C60–Ih core, with the ten CF3 groups arranged in an asymmetric para-para-para-meta-para-meta-para-meta-para (pmpmpmp) ribbon of edge-sharing C6(CF3)2 hexagons. There are no cage Csp–Csp bonds. There are intramolecular F F contacts between pairs of neighboring CF3 groups, ranging from 2.565 (1) to 2.727 (1) Å.

Electric-arc synthesis of soot with a high content of higher fullerenes

The influence of potassium carbonate additions from 1 to 12 wt % and the helium pressure on the content of higher fullerenes C76, C78, C80, C82, C84, C86, etc., in soot is studied. The optimum conditions of the evaporation of composite graphite electrodes are found: they provide the formation of soot with a high content of higher fullerenes (up to 11.4 wt %) in an extract.

Endohedral fullerene Gd2C2@C82 as a strongly correlated electron system

Isomerically pure endohedral fullerene with a gadolinium carbide cluster Gd2C2@C82(Cs) has been synthesized by the electric-arc method, extracted from soot by o-dichlorobenzene, separated chromatographically, and characterized by mass spectroscopic and spectrophotometric methods. The energy and optical absorption spectra of the synthesized compound have been calculated for the first time within the Hubbard model. Good agreement of the experimental and calculated optical absorption curves has been observed.