ESR spectra of fullerence C70 in concentrated sulfuric acid

It was established by ESR spectroscopy that the reaction of C₇₀ with concentrated H₂SO₄ resulted in the formation of isomeric dimers C₁₄₀ ⁺, and the action of H₂SO₄ on a toluene solution of C₇₀ ⁺ gave the C₇₀ radical cation. The structure of dimers was discussed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 208–210, January, 1999.     

Study of ESR spectra of fullerene C60 doped with magnesium and mercury

An increase in the intensity of the ESR signal and of its g value was observed in the course of annealing of the diamagnetic product of the reaction between magnesium amalgam and a toluene solution of C₆₀. The formation of a crystalline substance Mg_rC₆₀ with semiconductor properties was assumed. The ESR spectra of the products of vapor-phase synthesis of MgC₆₀ and Hg_rC₆₀ were recorded.Translated fromlzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2256–2258, September, 1996.     

Products of reaction of fullerene C60 with fuming sulfuric acid studied by IR and ESR spectroscopy

The products of reaction of fullerene C₆₀ with fuming sulfuric acid were precipitated from a solution with water and triethylamine and studied by IR and ESR spectroscopies. A comparison of the obtained data with the spectra of fullerene, dimers C₁₂₀ and C₁₂₀O, and fullerene polymers produced by photopolymerization allowed the conclusion that fullerene polymers were formed by fullerene oxidation with fuming sulfuric acid.     

An ESR study of radical reactions of C60 and C70

The results of ESR spectroscopic studies of radical reactions of fullerenes are presented. Reactivities of radicals of various chemical natures with respect to C₆₀ and C₇₀, delocalization of the unpaired electron in monofullerenyl radicals, and their reactivity are considered. The examples of dynamic effects in the ESR spectra of fullerenyl radicals, associated with the hindered rotation of the attached radicals, are presented. Characteristic features of the structures of the spin adducts resulting from polyaddition of free radicals to fullerenes and of fullerenyl radicals containing ²-bonded metaIloco mplexes are discussed.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 10, pp. 2396–2406, October, 1996.     

The ESR spectra of the spin-adducts of branched perfluorinated σ-radicals with fullerene-60

The ESR spectra of the radical adducts of the^.CF=CFC(CF₃)₃ and^.C(O)CF(CF₃)₂ radicals with C₆₀ are characterized by hyperfine interaction with the nucleus of the δ-fluorine atom located above the five-membered cycle in the fullerenyl radical. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1222–1224, June, 1997.     

Temperature dependence of the ESR line width of C60 − in C60 crystals doped with sodium, potassium, zinc, and indium

The ESR line width of the C₆₀ ⁻ anion in samples of fullerides (Na, K, Zn, and In) with low metal content (0.01%) is ∼0.1 mT at 77 K and ∼1 mT at 300 K. The line shape is fitted better by the Lorentzian function than by the Gaussian function. The spin-lattice relaxation likely makes some contribution to the line width. Time-dependent changes in the ESR spectra were observed: they are related to diffusion of cations to defects of the crystalline lattice. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 669–672, April, 1998.     

ESR study of spin-adducts of trimethylaminoboryl radicals with fullerene C60

It was established by ESR that trimethylaminoboryl radicals formed by UV irradiation of BH₃NMe_6w in the presence of di-tert-butyl peroxide in saturated benzene solutions of fullerene C₆₀, add to fullerenes to give C₆₀-BH₂NMe₃ spin-adducts. The latter undergo dimerization with a rate constant ofca. 2.5 · 10⁶ L mol^–1 s^–1. A more prolonged photolysis of excess BH₃NMe₃ in a benzene solution of C₆₀ results in multiple addition of the trimethylaminoboryl radicals to the fullerene to give stable radicals C₆₀[BH₂NMe₃]_n.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 673–675, April, 1994.     

ESR studies of doping C60 fullerene by zinc, cadmium, copper, gallium, and indium vapors

In the ESR spectra recorded at the beginning of the doping reaction of C₆₀ fullerene by zinc, gallium, and indium vapors, signals corresponding to C₆₀ ⁻ were observed. In the course of reduction, these signals disappeared and reversibly transformed into the signals of higher charged C₆₀ ⁿ⁻ anions. In the case of cadmium and copper, only the spectra of C₆₀ ⁿ⁻ were recorded. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 303–305, February, 1997.     

An ESR study of the products of multiple addition of diisopropoxyphosphoryl radicals to C60

The ESR spectra of the radicals resulting from the multiple addition of diisopropoxyphosphoryl radicals to C₆₀ have been studied. The formation of six different types of radical adducts was detected. A structure for the stable product, characterized by hyperfine coupling of the unpaired electron with two phosphorus nuclei, was proposed. The unpaired electron in C₆₀P(O)(OPrⁱ)₂ is delocalized in the same way as in alkylfullerenyl radicals,i.e., mainly over the two six-membered rings adjacent to the C-CP(O)(OPrⁱ)₂ bond.Translated fromIzvestiya Akademii Nauk. Seriva Khimicheskaya, No. 11, pp. 2679–2682, November, 1996.     

ESR study of formation of allylic radicals in simultaneous photochemical generation of phosphoryl and carbon-centered radicals in the presence of C60 fullerene

Allylic radicals resulting upon simultaneous photochemical generation of phosphoryl [^.P(O)(OPrⁱ)₂] and carbon-centered [^.C(O)OMe,^.CH₃,^.CCl₃] radicals in saturated toluene solutions of C₆₀ have been studied by the ESR method. The donor-acceptor properties of carbon-centered radicals determine the positions of phosphoryl groups in the allylic system.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2422–2424, December, 1995.This work was performed under terms of the Russian Interdisciplinary Scientific and Technical Program Fullerenes and Atomic Clusters and was financially supported by the Russian Foundation for Basic Research (Project Nos. 93-03-18725 and 93-03-4101) and the International Scientific and Technical Center (Grant No. 079 (B)).     

Doping mechanism of C60 fullerene by sodium and potassium

ESR spectra of localized states of KC₆₀ and K₂C₆₀ and conducting electrons of K₃C₆₀ were recorded in the process of doping C₆₀ by potassium. The ESR spectra of K _x C₆₀ (x < 3) and Na _x C₆₀ correspond to the semiconductive state of the samples.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2190–2195, November, 1995.This work was financially supported by the Russian Foundation for Basic Research (Project No. 93-03-4101). The work was performed under terms of the interindustry program Fullerenes and Atomic Clusters.     

ESR study of spin-adducts of boron-centered carboranyl radicals with fullerene-60 and fullerene-70

Spin-adducts of boron-centered radicals, derivatives ofm-carboran-12, with fullerenes C₆₀ and C₇₀ have been studied by ESR spectroscopy. Constants of hyperfine splitting (HFS) of an unpaired electron with¹⁰B and¹¹B nuclei have been determined from the ESR spectra of C₆₀-B₁₀H₉C₂H₂ radicals. Three isomeric spin-adducts were detected with different HFS constants with¹¹B, andg-factors were detected in the reaction of B₁₀H₉C₂H₂ with C₇₀.Dedicated to Academician of the RAS N. S. Zefirov (on his 60th birthday).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1840–1842, September, 1995.This study was performed in the framework of the International Research Program of Russia Fullerenes and Atomic Clusters and was financially supported by the Russian Foundation for Basic Research (Project Nos. 93-03-18725 and 93-03-4101).     

ESR study of adducts of diisopropylphosphoryl radicals with C60C[P(O)(OEt)2]2 2 isomers

The radical adducts of the P^·(O)(OPrⁱ)₂ (R^·) radicals with C₆₀C[P(O)(OEt)₂]_{2 2} fullerene derivatives were studed by ESR spectroscopy. The number of stable regioisomers of phosphorylfullerenyl radicals formed by addition of the phosphoryl radicals to the C₆₀C[P(O)(OEt)₂]_{2 2} isomers depends on the mutual position of the organophosphorus groups and decreases in the series trans-2 > trans-3 trans-4 > e. The rate constants for addition of the R^· radicals to the trans-3 regioisomer (k = 1.7·10⁸ L mol^–1 s^–1) were determined.     

ESR spectra of paramagnetic palladium complexes

Binuclear nitrosopalladium complexes Pd₂(μ-COOR)₂(η²-CH₂C₆H₄NO)₂ (R = Me, CF₃, or Ph) were studied by ESR spectroscopy. Analysis of parameters of ESR spectra of the polycrystalline samples and their toluene solutions suggests partial izomerization of the nitroso ligands to the nitroxide form to result in the oxidation of palladium(II) to palladium(III). __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1746–1751, August, 2005.     

The ESR study of the influence of fluorinated alcohols on spin-adducts of phosphoryl radicals with C60 and C70: a change of magnetic resonance parameters and exclusive formation of monoadducts

Complex formation of^.C₆₀P(O)(OPrⁱ)₂ or three isomers of^.C₇₀P(O)(OPrⁱ)₂ with fluorinated alcohols CF₃CH₂OH (1), (CF₃)₃COH (2), and (CF₃)₂CHOH (3) results in an increase in the hyperfine splitting constants with the³¹P nucleus by approximately 3–4 G. Only monoadducts are formed when alcohols1–3 are added to toluene saturated solutions of Hg[P(O)(OPrⁱ)₂]₂ and C₆₀ under photochemical conditions of multi-addition of phosphoryl radicals to C₆₀. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1869–1871, September, 1998.     

Reduction of C60 and C70 by primary amines: Optical and ESR studies

Radical anions C70- and C70 2- were obtained in vacuo by the reaction of I-amino3-propanol (AP) and 1,5-diaminopentane (DAP) with fullerene C70. The radical anions were identified by visible/near IR (X = I372 and I172 nm, respectively) and ESR spectroscopies. The temperature dependences of the ESR spectra were studied for the C₆₀-AP, C₇₀-AP, and C70-DAP systems. At low temperatures (I5-45 K), the ESR spectrum for C60 is close to that for species with axial symmetry of theg-factor (q_| = 2.000 and g, = I.995). The anisotropy of theg-factor is averaged, when the temperature increases. At T > I48 K the averaged line is broadened, and the sharp signal with g = 2.0001 overlaps this broad line. The intensity of the narrow line increases, when the temperature increases. The ESR spectrum observed in the C₇₀-AP system at I2.5 K may be tentatively described as a superposition of two ESR spectra, namely, the ESR spectra of a radical with g_| = 2.0042 and g, = 2.0015 (presumably a radical cation) and of C₇₀ ^– with q_| = 2.000 and g = I.994. The spectra of the sample in which C70 is present mainly as C₇₀ ^2– exhibit only a line with g = 2.0004.Translated from Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. I, pp. 103–108, January, 1996.     

Formation of the fullerene radical anion in the reaction of C60 with phosphorous triamides

Fullerene C₆₀ reacts with phosphorous acid triamides to give the radical anion. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 201–203, January, 2008.     

ESR study of the photolysis of C60Cl6

The photolysis of C₆₀Cl₆ in the presence of α-phenyl-N-tert-butylnitron (PBN) as a spin trap was studied by ESR spectroscopy. It was shown that a C−Cl bond undergoes homolytic cleavage to give a stable fullerenyl radical of the cyclopentadienyl type, whose formation was confirmed by quantum-chemical computations. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 752–754, April, 2000.     

Radical functionalization of [60]fullerene and its derivatives initiated by the C(CF3)2C6H4F radical

It was found that the 2-(p-fluorophenyl)hexafluoroisopropyl radical produced by thermal dissociation of the Polishchuk dimer [C(CF₃)₂C₆H₄F]₂ can withdraw, under mild conditions, the H atom from the methyl group of toluene and mesitylene to form the corresponding radicals, whose addition to [60]fullerene occurs more selectively than in the case of photochemical production of these radicals. Dynamics of the step-by-step multiaddition of the radicals to C₆₀ was studied by ESR. It was found that the addition of benzyl radicals affords adducts containing from 3 to 5 benzyl groups, whereas no spin-adducts with five addends were observed for more bulky 3,5-dimethylphenylmethyl radicals. The interaction of 3,5-dimethylphenylmethyl radicals with the metal complexes (η²-C₆₀[IrH(CO)(PPh₃)₂] and (η²-C₆₀[Pd(PPh₃)₂] was studied for the first time. It was shown that the palladium derivative undergoes only demetallation. In the case of the Ir complex, up to 3 radicals add to the fullerene ligand in the same hemisphere where the transition metal is coordinated. The reaction rates are ∼5 times lower than those for C₆₀. The ability of 2-(p-fluorophenyl)hexafluoroisopropyl radicals to dehydrogenate C₆₀H₃₆ was found. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1119–1123, June, 1999.     

ESR study of the effect of fluorinated alcohols on magnetic resonance parameters of spin-adducts of phosphoryl radicals with products of cycloaddition of substituted nitriloxides to C60

Regioselectivity of the addition of phosphoryl radicals to the products of cycloaddition of substituted nitriloxides to fullerene C₆₀ was studied by ESR spectroscopy. The effect of fluorine-containing alcohols on the magnetic resonance parameters of the isomers of spinadducts of phosphoryl radicals located at different distances from the five-membered heterocycle was studied. Complexation of the obtained isomeric spin-adducts with (CF₃(₃COH leads to a 3 to 5 G increase in the constant of hyperfine interaction with the phosphorus nucleus, which makes it possible to observe additional lines in the ESR spectrum. Deceased. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1808–1811, September, 1999.