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Three compounds that display the skew-pentagonal-pyramid (SPP) [C.sub.s]-[C.sub.60][X.sub.6] or [C.sub.s]-[C.sub.60][X.sub.4]O addition patterns are described. All three compounds have demonstrated that the SPP addition pattern is at least kinetically stable and the high temperature synthesis of the two epoxides have indicated that perfluoroalkyl substituents can enhance the thermal stability of fullerene derivatives with other substituents.

The isolation of 1,9-and 1,7-C60F(CF3) from a high-temperature C60/K2Pt F6 reaction mixture is described. It was found that the dominant coupling mechanism is through-space coupling rather than through-bond coupling.

A new method enables the preparation of cationic silver (I) carbonyl complexes (Ag(CO))+ and (Ag(CO)2)+ as salts of a number of anions having the OTeF5 group. These crystalline compounds are stable under a CO atmosphere or at low temperatures. Manometric and spectroscopic studies of these compounds reveal the absence of Ag to carbon pi-back-bonding, indicating that they belong to a group of nonclassical metal cabonyls. X-ray crystallographic studies help characterize two of the new compounds.

The structures of [K.sub.2][([H.sub.2]O).sub.2][B.sub.12][F.sub.12] and [K.sub.2][([H.sub.2]O).sub.4][B.sub.12][F.sub.12] are determined by using X-ray diffraction. The rates of absorption and desorption of [H.sub.2]O from unit cells at the surface of the microcrystals and the rate of diffusion of [H.sub.2]O across the moving [K.sub.2][([H.sub.2]O).sub.2][B.sub.12][F.sub.12(s)]/[K.sub.2][B.sub.12][F.sub.12(s)] phase boundary, are faster than the fastest rates of change in sample mass due to hydration and dehydration.

A combination of the electron spin resonance (ESR) and vis- near-infrared (NIR) spectroelectrochemistry techniques is employed to explain the charge state and properties of the [C.sub.60][(C[F.sub.3]).sub.2n] (2n = 2- 10) derivatives.

The article explains the synthesis, composition and properties of the various soluble chlorofullerenes [C.sub.60][Cl.sub.2,4,6,8,10]. The x-ray structure of the [C.sub.1]-[C.sub.60][Cl.sub.10] complex is also studied.

The optimization of the [F.sub.2] perfluorination of [K.sub.2][B.sub.12][H.sub.12] in acetonitrile with continuous bubbling of [F.sub.2]/[N.sub.2] has shown that HF and other protic acids have inhibited each of the fluorination steps and the fluorination has taken place at the gas bubble-solution interface. The DFT studies haves shown that these two phenomena are related by the relative propensities of [B.sub.12][H.sub.12-x][F.sub.x.sup.2-] anions to partition from bulk solution to the interface.

The synthesis, as well as the various properties of the [Sc.sub.3]N@[([C.sub.80]-[I.sub.h](7))([CF.sub.3]).sub.14] and [Sc.sub.3]N@[([C.sub.80]-[I.sub.h](7))([CF.sub.3]).sub.16]. endohedral metallofullerene derivatives with exohedral addends on four and eight triple-hexagon junctions are discussed.

The isolation and characterization of twenty-one new fullerene[(C[F.sub.3]).sub.n] and several other hollow-higher-fullerene (HHF) cages are reported. The studies discovered addition-pattern principle for HHFs, the most pyramidal cage atoms in the parent HHF which form the most electron-rich and the most reactive cage C-C bonds.

The preparation, isolation and spectroscopic and electrochemical characterization of the first C[F.sub.3] derivatives of both isomers of [Sc.sub.3]N@[C.sub.80] are described. The results have shown that the metallic nitride fullerenes (MNFs) [Sc.sub.3]N@([C.sub.80]-[I.sub.h]) and [Sc.sub.80]N@([C.sub.80]-[D.sub.5h]) are transformed into fluoroalkylated derivatives.

A combination of electrochemical state, electronic, fluorescence and ESR spectra and density functional theory (DFT) calculations are used for the 22 known [C.sub.60][(C[F.sub.3]).sub.n] derivatives. The results for the [C.sub.60][(C[F.sub.3]).sub.n] compounds and the additional [C.sub.60][(X).sub.n] compounds have provided insights into the frontier orbitals of [C.sub.60][(X).sub.n] derivatives.

A significant improvement in the selectivity of fullerene trifluoromethylation reactions is achieved using a stream of CF3I flowing through a hot tube containing either C60 or C70. The predominant products in the C60 reaction, an estimated 40+ mol % of the cold-zone condensate, were three isomers of C60-(CF3)10 that were purified by two- or three-stage HPLC.

A demonstration that Th-C60Br24 reacts with XeF2 dissolved in a HF to produce Th-C60F24 with ca. 80% compositional purity is presented. Some transformation of fullerene derivatives to fluorofullerenes could be highly regioselective and lead to relatively pure samples of novel flurofullerenes and fluorofullerene derivatives.

The synthesis and physiochemical properties of the dodecafluoro-closo-dodecaborate(2-) anion, B12F12(super 2-) are investigated. A significantly lower-temperature synthesis of K2B12F12 in 72 percent recrystallized yield is reported.

The facile conversion of ((eta6-C6H6)Rh(CO)2)(1-Et-CB11F11) into the nonclassical rhodium(I) carbonyl (Rh(CO)4)(1-Et-CB11F11) is reported.

A study relating to the incorporation of one or more organic fluorine atoms into biologically active compounds reports the synthesis and characterization of the first member of a new class of fluorinated alcohols. This new class of fluorinated alcohols may facilitate more detailed, systematic investigations of inter- and intramolecular O-H...FC hydrogen bonding. Experimental methods, findings and conclusions are discussed.

A study was conducted on highly fluorinated weakly coordinating monocarborane anions. CB11H12- and the related carbonate ion CB9H(sub 10)(super -9) was polyfluorinated using a supercritical HF. Findings showed that CB11H12- was converted to 1-H-CB11F11- and the compound (NMe3H)(1-H-CB11F11) was converted to (NMe3H)(1-CH3-CB11-F11). Moreover, a protonolysis of the Cu-C(mesityl) bond and formation of [N(n-Bu)4]2[CuCl(CB11F11)] can result from the dichloromethane of [Cu(mesityl)](sub n)(super 16). These results indicate that carborane dianions having 11 nonmetal substituents may be valuable as new ligands.

Structures of K2(H2O)2B12F12 and K2(H2O)4B12F12 were determined by X-ray diffraction. They contain [K(μ-H2O)2K]2+ and [(H2O)K(μ-H2O)2K(H2O)]2+ dimers, respectively, which interact with superweak B12F122- anions via multiple K∙∙∙F(B) interactions and (O)H∙∙∙F(B) hydrogen bonds (the dimers in K2(H2O)4B12F12 are also linked by (O)H∙∙∙O hydrogen bonds). DFT calculations show that both dimers are thermodynamically stabilized by the lattice of anions: the predicted ΔE values for the gas-phase dimerization of two K(H2O)+ or K(H2O)2+ cations into [K(μ-H2O)2K]2+ or [(H2O)K(μ-H2O)2K(H2O)]2+ are +232 and +205 kJ mol-1, respectively. The calculations also predict that ΔE for the gas-phase reaction 2 K+ + 2 H2O →[K(μ-H2O)2K]2+ is +81.0 kJ mol, whereas ΔH for the reversible reaction K2B12F12(s) + 2 H2O(g) →K2(H2O)2B12F12(s) was found to be -111 kJ mol-1 by differential scanning calorimetry. The K2(H2O)O,2,4B12F12 system is unusual in how rapidly the three crystalline phases (the K2B12F12 structure was reported recently) are interconverted, two of them reversibly. Isothermal gravimetric and DSC measurements showed that the reaction K2B12F12 (s) + 2 H2O(g) K2(H2O)2B12F12 (s) was complete in as little as 4 min at 25 °C when the sample was exposed to a stream of He or N2 containing 21 Torr H2O(g). The endothermic reverse reaction required as little as 18 mm when K2(H2O)2B12F12 at 25 °C was exposed to a stream of dry He. The products of hydration and dehydration were shown to be crystalline K2(H2O)2B12F12 and K2B12F12, respectively, by PXRD, and therefore these reactions are reconstructive solid-state reactions (there is also evidence that they may be single-crystal-to-single-crystal transformations when carried out very slowly). The hydration and dehydration reaction times were both particle-size dependent and carrier-gas flow rate dependent and continued to decrease up to the maximum carrier-gas flow rate of the TGA instrument that was used, demonstrating that the hydration and dehydration reactions were limited by the rate at which H2O(g) was delivered to or swept away from the microcrystal surfaces. Therefore, the rates of absorption and desorption of H2O from unit cells at the surface of the microcrystals, and the rate of diffusion of H2O across the moving K2(H2O)2B12F12(s)/K2B12F12 )(s) phase boundary, are even faster than the fastest rates of change in sample mass due to hydration and dehydration that were measured. The exchange of 21 Torr H20(9) with either D2O or H218O in microcrystalline K2(D2O)2B12F12 or K2(H218O)2B12F12 at 25 °C was also facile and required as little as 45 min to go to completion (H2O(g) replaced both types of isotopically labeled water at the same rate for a given starting sample of K2B12F12, demonstrating that water molecules were exchanging, not protons. Significant portions of mass (m) vs time (t) plots for the 1,2H2O(g)/K2(2,1H2O)2B12F12(s) exchange reactions fit the equation m ∞ e-kt, with 103k = 1 .9 s-1 for one particle size distribution and 103k = 0.50 s-1 for another. Finally, K2(H2O)2B12F12 was not transformed into K2(H2O)4B12F12 after prolonged exposure to 21 Torr H2O(9) at 25 °C, 37 Torr H2O(g) at 35 °C, or 55 Torr H2O(g) at 45 °C. [ABSTRACT FROM AUTHOR]

During the optimization of the F2 perfluorination of K2B12H12 in acetonitrile with continuous bubbling of 20/80 F2/N2, it was discovered that (i) HF and other protic acids inhibit each of the 12 fluorination steps (in contradiction to recently published findings) and (ii) the fluorinations appear to take place at the gas bubble-solution interface. Experimental results and DFT calculations suggest that these two phenomena are related by the relative propensities of the various B12H12-xFx2- anions to partition from bulk solution to the interface (i.e., their relative polarizabilities or softness; 0 ⩽ x ⩽ 12). Relative to the previously reported syntheses of K12B12F12 or Cs2B12F12, the new optimized procedure has the following advantages: (i) the scale was increased 10-fold without sacrificing yield (74% for K12B12F12, 76% for Cs2B12F12) or purity (99.5+%); (ii) the reaction/purification time was decreased from ca. 1 week to 2 days; and (iii) the solvent was changed from anhydrous HF to acetonitrile, allowing ordinary glassware to be used. The anhydrous salt Cs2B12F12 was found to be thermally stable up to 600 °C. [ABSTRACT FROM AUTHOR]

The charged states of C60(CF3)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 CF3 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. [ABSTRACT FROM AUTHOR]

The efficacy of various analytical techniques for the characterization of products of C60 chlorination reactions were evaluated by (i) using samples of C60Cl6 of known purity and (ii) repeating a number of literature syntheses reported to yield pure C60Cln compounds. The techniques were NMR, UV-vis, IR, and Raman spectroscopy, FAB, MALDI, LDI, ESI, and APCI mass spectrometry, HPLC, TGA, elemental analysis, and single-crystal X-ray diffraction. Most of these techniques are shown to give ambiguous or erroneous results, calling into question the composition and/or purity of nearly all C60Cln compounds reported to date. The optimum analytical method for chlorofullerenes was found to be a combination of HPLC and either MALDI or APCI mass spectrometry. For the first time, the chlorination of C60 by ICl, ICl3, and Cl2 was studied in detail using dynamic HPLC analysis and APCI mass spectrometry. Suitable conditions were found for the preparation of the new chlorofullerenes 1,7-C60Cl2, 1,9-C60Cl2, 1,6,9,18-C60Cl4, and 1,2,7,10,14,24,25,28,29,31-C60Cl10. The latter compound was also studied by 13C NMR spectroscopy and X-ray diffraction, which led to the unambiguous determination of its asymmetric addition pattern. The unusual structure of C60Cl10 was compared with other possible isomers using DFT-predicted relative energies. These results, along with additional experimental data and an analysis of the DFT-predicted frontier orbitals of likely intermediates, were used to rationalize the formation of the new compound C60Cl10 from C60Cl6 and excess ICl without the rearrangement of any C-Cl bonds. For the first time, the stability of C60Cln compounds under a variety of conditions was studied in detail, leading to the discovery that they are, in general, very light-sensitive in solution. The X-ray structure of C60Cl6 was also redetermined with higher precision. [ABSTRACT FROM AUTHOR]

The compounds Sc3N@(C80-/h(1))(CF3)14(1) and Sc3N@(C80-/h(7))(CF3)16 (2) were prepared by heating Sc3N@C80-Ih(7) and Ag(CF3CO2) to 350 °C in a sealed tube. The structures of 1 and 2 were determined by single-crystal X-ray diffraction. They are the first X-ray structures of any endohedral metallofullerene with more than four cage C(sp³) atoms. The structures exhibit several unprecedented features for metallic nitride fullerenes, including multiple cage sp³ triple-hexagon junctions (four on 1 and eight on 2), no cage disorder and little (2) or no (1) endohedral atom disorder, high-precision (C-C esd's are 0.005 Å for 1 and 0.002 Å for 2), an isolated aromatic C(sp²)6 hexagon on 2, and two negatively charged isolated aromatic C(sp²)6 pentagons on 2 that are bonded to one of the Sc atoms. DFT calculations are in excellent agreement with the two Sc3N conformations observed for 2 (ΔE(calc) = 0.36 kJ mol-1; ΔE(exp) = 0.26(2) kJ mol-1). [ABSTRACT FROM AUTHOR]

The frontier orbitals of 22 isolated and characterized C60(CF3)n derivatives, including seven reported here for the first time, have been investigated by electronic spectroscopy (n = 2 [1], 4 [1], 6 [2], 8 [5], 10 [6], 12 [3]; the number of isomers for each composition is shown in square brackets) fluorescence spectroscopy (n = 10 [4]), cyclic voltammetry under air-free conditions (all compounds with n = 12), ESR spectroscopy of C60(CF3)n- radical anions at 25 00 (n = 4 [1] and 10 [1]), and quantum chemical calculations at the DFT level of theory (all compounds including n = 16 [3] and 18 [2]). DFT calculations are also reported for severaI hypothetical C60(CF3)n derivatives. The X-ray structure of one of the compounds, 1,6,11,16,18,26,36,41,44,57-C60(CF3)10, is reported here for the first time. Most of the compounds with n ≤ 12 exhibit two or three quasi-reversible reductions at scan rates from 20 my s-1 up to 5.0 V s-1 respectively. The 18 experimental 0/- E1/2 values (vs C60-1) are a linear function of the DFT-predicted LUMO energies (average E1/2 deviation from the least-squares line is 0.02 V). This linear relationship was used to predict the 0/- E1/2 values for the n = 16 and 18 derivatives, and none of the predicted values is more positive than the 0/- E1/2 value for one of the isomers of C60(CF3)n. In general, reduction potentials for the 0/- couple are shifted anodically relative to the C600/- couple. However, the 0/- E1/2 values for a given composition are strongly dependent on the addition pattern of the CF3 groups. In addition, LUMO energies for isomers of C60(X)n (n = 2, 4, 6, 8, 10, and 12) that are structurally related to many of the CF3 derivatives were calculated and compared for X = CH3, H, Ph, NH2, CH2F, CHF2, F, NO2, and ON. The experimental and computational results for the C60(F3)n compounds and the computational results for more than 50 additional C60(X)n compounds provide new insights about the frontier orbitals of C60(X)n derivatives. For a given substituent, X, the addition pattern is as important, if not more important in many cases, than the number of substituents, n, in determining E1/2 values. Those addition patterns with double bonds in pentagons having two C(sp²) nearest neighbors result in the strongest electron acceptors. [ABSTRACT FROM AUTHOR]

Reaction of a mixture of insoluble higher fullerenes with CF3I at 500 °C produced a single abundant isomer of C74(CF3)12, C76(CF3)12, and C80(CF3)12, two abundant isomers of C78(CF3)12 and C82(CF3)12, and an indeterminant number of isomers of C84(CF3)12. Using a combination of 19F NMR spectroscopy, DFT calculations, and the structures and spectra of previously reported fullerene(CF3)n compounds, the most-probable structures of six of the seven isolated compounds were determined to be specific isomers of C2-(C74-D3h)(CF3)12, Cs-(C76-Td(2))(CF3)12), C2-(C78-D3h(5))(CF3)12), Cs-(C80-C2v(5))(CF3)12), C2-(C82-C2(5))-(CF3)12), and C2-(C82-C2(3))(CF3)12) containing ribbons and/or loops of edge-sharing para-C6(CF3)2 hexagons. The seventh isolated compound is a C1 isomer of C78(CF3)12 containing two such ribbons. This set of compounds represents only the second reported isolable compound with the hollow C74-D3h cage and the first experimental evidence for the existence of the hollow fullerenes C76-Td(2), C78-D3h(5), C80-C2v(5), and C82-C2(5) in arc-discharge soots. [ABSTRACT FROM AUTHOR]

Reaction of C60 with CF3I at 550 °C, which is known to produce a single isomer of C60(CF3)2,4,6 and multiple isomers of C60(CF3)8,10, has now been found to produce an isomer of C60(CF3)6 with the Cs-C60X6 skew-pentagonal-pyramid (SPP) addition pattern and an epoxide with the Cs-C60X4O variation of the SPP addition pattern, Cs-C60(CF3)4O. The structurally similar epoxide Cs-C60(C2F5)4O is one of the products of the reaction of C60 with C2F5I at 430 °C. The three compounds have been characterized by mass spectrometry, DFT quantum chemical calculations, Raman, visible, and 19F NMR spectroscopy, and, in the case of the two epoxides, single-crystal X-ray diffraction. The compound Cs-C60(CF3)6 is the first [60]-fullerene derivative with adjacent Rt groups that are sufficiently sterically hindered to cause the (DFT-predicted) lengthening of the cage (CF3)C-C(CF3) bond to 1.60 Å as well as to give rise to a rare, non-fast-exchange-limit 19F NMR spectrum at 20 °C. The compounds Cs-C60(CF3)4O and Cs-C60(C2F5)4O are the first poly(perfluoroalkyl)fullerene derivatives with a non-fluorine-containing exohedral substituent and the first fullerene epoxides known to be stable at elevated temperatures. All three compounds demonstrate that the SPP addition pattern is at least kinetically stable, if not thermodynamically stable, at temperatures exceeding 400 °C. The high-temperature synthesis of the two epoxides also indicates that perfluoroalkyl substituents can enhance the thermal stability of fullerene derivatives with other substituents. [ABSTRACT FROM AUTHOR]

Milligram amounts of the new compounds 1,9- and 1,7-C60F(CF3) (Ca. 85:15 mixture of isomers) and C60F3(CF3) were isolated from a high-temperature C60/K2PtF6 reaction mixture and purified to 98 mol % compositional purity by two-dimensional high-performance liquid chromatography using Buckyprep and Buckyclutcher columns. The previously observed compounds C60F5(CF3) and C60F7(CF3) were also purified to 90+ mol % for the first time. Variable-temperature 19F NMR spectra of the mixture of C60F(CF3) isomers and the previously reported mixture of Cs- and C1-C60F17(CF3) isomers demonstrate for the first time that fullerene(F)n(CF3)m derivatives with adjacent F and CF3 substituents exhibit slow-exchange limit hindered CF3 rotation spectra at -40 ± 10 °C. The experimental and density functional theory (DFT) predicted ΔH‡ values for CF3 rotation in 1,9-C60F(CF3) are 46.8(7) and 46 kJ mol-1, respectively. The DFT-predicted ΔH‡ values for 1,7-C60F(CF3), Cs-C60F17(CF3), and C1-C60F17(CF3) are 20, 44, and 54 kJ mol-1, respectively. The ≥4JFF values from the slow-exchange-limit 19F spectra, which vary from ca. 0 to 48(1) Hz, show that the dominant nuclear spin-spin coupling mechanism is through-space coupling (i.e., direct overlap of fluorine atom lone-pair orbitals) rather than coupling through the σ-bond framework. The 2JFF values within the CF3 groups vary from 107(1) to 126(1) Hz. Collectively, the NMR data provide an unambiguous set of ≥4JFF values for three different compounds that can be correlated with DFT-predicted or X-ray diffraction derived distances and angles arid an unambiguous set of 2JFF values that can serve as an internal standard for all future JFF calculations. [ABSTRACT FROM AUTHOR]

A significant improvement in the selectivity of fullerene trifluoromethylation reactions was achieved. Reaction of trifluoroiodomethane with [60]fullerene at 460 °C and [70]fullerene at 470 °0 in a flow reactor led to isolation of cold-zone-condensed mixtures of C60(CF3)n and C70(CF3)n compounds with narrow composition ranges: 6 ≤ n ≤ 12 for C60(CF3)n and 8 ≤ n ≤ 14 for C70(CF3)n. The predominant products in the C60 reaction, an estimated 40+ mol % of the cold-zone condensate, were three isomers of C60(CF3)10. Two of these were purified by two-stage HPLC to 80+% isomeric purity. The third isomer was purified by three-stage HPLC to 95% isomeric purity. Thirteen milligrams of this orange-brown compound was isolated (5% overall yield based on C60), and its C1-symmetric structure was determined to be 1,3,7,10,14,17,23,28,31,40-C60(CF3)10 by X-ray crystallography. The CF3 groups are either meta or para to one another on a p-m-p-p-p-m-p-m-p ribbon of edge-sharing C6(CF3)2 hexagons (each pair of adjacent hexagons shares a common CF3 group). The selectivity of the C70 reaction was even higher. The predominant product was a single C70(CF3)10 isomer representing >40 mol % of the cold-zone condensate. Single-stage HPLC led to the isolation of 12 mg of this brown compound in 95% isomeric purity (27% overall yield based on converted C70). The new compounds were characterized by EI or S8-MALDI mass spectrometry and 2D-COSY 19F NMR spectroscopy. The NMR data demonstrate that through-space coupling via direct overlap of fluorine orbitals is the predominant contribution to JFF values in these and most other fullerene(CF3)n compounds. [ABSTRACT FROM AUTHOR]

The article focuses on the preparation, isolation and electrochemical characterization of the first trifluoromethylation derivatives of both isomers of Sc3N@C80. The compounds used in the experiment were extracted from the crude product mixture with organic solvents. Results of the study indicate that the compound can be readily transformed into fluoroalkylated derivatives by utilizing high-temperature radical addition methodologies.