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91.
E. N. Shaposhnikova S. R. Sterlin S. P. Solodovnikov N. N. Bubnov A. I. Chernyavskii A. L. Chistyakov I. V. Stankevich B. L. Tumanskii 《Russian Chemical Bulletin》1998,47(1):60-65
The structure and reactivity of α-ketoradicals, derivatives of (CF3)3CC(O)C(O)CF3 (1), were studied by ESR spectroscopy. The photoreduction of α-diketone1 in a solution of cyclohexane in perfluorodipentyl ether results in the formation of radicals of two types, (CF3)3CC(2)(O(4))·C(3)(O(6)H)CF3 (1a) and (CF3)3C·C(OH)C(O)CF3 (1b) in a ∼40∶1 ratio. The degree of delocalization of the spin density in two conformers of radical1a was calculated by the MNDO/PM3 method in the UHF approximation. It was established that radicals1a and1b are capable of reversible dimerization. The rate constant of dimerization and the enthalpy of the radical—dimer equilibrium
were measured for radical1a. A decrease in the rate of dimerization of radical1a upon addition of complexing solvents ((CF3)3COH andp-CF3C6H4CF3) was found. The influence of the solvents on the rate of dimerization was also detected for α-ketoradical (CF3)3CC(O)·C(OSiMe2Ph)CF3 (1c).
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 62–67, January, 1998. 相似文献
92.
Tumanskii B Pine P Apeloig Y Hill NJ West R 《Journal of the American Chemical Society》2005,127(23):8248-8249
The first radical adducts of a stable N-heterocyclic germylene were investigated. Novel radical species were produced from a variety of precursors and studied by EPR spectroscopy. DFT (B3LYP) calculations of radical adducts of different (C, Si, Ge) unsaturated N-heterocyclic divalent species with phenoxyl radical show that in the radicals studied the unpaired electron is delocalized over the five-membered ring and the spin density on the central atoms decreases in the following order: C > Si > Ge. These trends can be understood in terms of zwitterionic structure of radical adducts. 相似文献
93.
B. L. Tumanskii V. V. Bashilov S. P. Solodovnikov N. N. Bubnov V. I. Sokolov 《Russian Chemical Bulletin》1995,44(9):1771-1772
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). 相似文献
94.
B. L. Tumanskii V. V. Bashilov S. P. Solodovnikov N. N. Bubnov A. A. Khodak 《Russian Chemical Bulletin》1994,43(9):1582-1584
ESR spectra of phosphorus-containing fullerenyl radicals.C60-P(O)(OPr1)2 and. C60-P(O)(OEt)Ph were studied at low temperatures (193–273 K). A decrease in the rate of rotation of organophosphorus group around the C-P bond results first in line broadening and then in the appearance of two doublets due to two extreme conformations, which have differentg-factors and hyperfine coupling constants (HCC) of the unpaired electron with the31P nucleus. The kinetic and thermodynamic parameters of the conformational isomerism were calculated.The widely used appellation of such radicals as dialkoxyphosphonyl ones does not correspond to the IUPAC nomenclature.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1671–1673, September, 1994.This work was supported by the Russian Foundation for Basic Research (Projects No. 93-03-18725 and 93-03-4101). 相似文献
95.
Radical functionalization of [60]fullerene and its derivatives initiated by the C(CF3)2C6H4F radical
B. L. Tumanskii O. G. Kalina V. V. Bashilov A. V. Usatov E. A. Shilova Yu. I. Lyakhovetskii S. P. Solodovnikov N. N. Bubnov Yu. N. Novikov A. S. Lobach V. I. Sokolov 《Russian Chemical Bulletin》1999,48(6):1108-1112
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. 相似文献
96.
R. G. Gasanov O. G. Kalina V. V. Bashilov B. L. Tumanskii 《Russian Chemical Bulletin》1999,48(12):2344-2346
The rate constants of addition of the.CMe3,.CH2Me,.CH2(CH2)3Me,.CH2Ph,.CH2CH=CH2, and.CH(Me)Et radicals to fullerene C60 were determined by the method of competitive addition of free radicals to spin traps.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp 2369–2372, December, 1999. 相似文献
97.
E. N. Shaposhnikova S. R. Sterlin S. P. Solodovnikov N. N. Bubnov B. L. Tumanskii 《Russian Chemical Bulletin》1999,48(3):470-473
The addition of element-centered radicals to perfluorinated α-triketones (CF3)2CFCOCOCOC2F5 (1) and (CF3)2CFCOCOCO(CF3)2 (2) was studied by the ESR method. In the case of Si-centered radicals, α-siloxydiketomethyl radicals are formed, which are
characterized by the highest delocalization of an unpaired electron. The dimerization of these radicals is characterized by
a low value of the enthalpy of the radical—dimer equilibrium (2.7 kcal mol−1). The Ge(C6F5)3 and ·Mn(CO)5 radicals are added to1 at the carbonyl group directly bound to the pentafluoroethyl substituent. The hindered rotation of the (CF3)2CF group was observed for the spin-adduct of ·Ge(C6F5)3 with2.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 474–477, March, 1999. 相似文献
98.
R. G. Gasanov V. V. Bashilov O. G. Kalina B. L. Tumanskii 《Russian Chemical Bulletin》2000,49(9):1642-1644
The rate constants of the addition of phosphoryl radicals to fullerenes C60 and C70 were determined by the method of competitive reactions. The phosphoryl radicals were shown to be 1.5–3 orders of magnitude
more reactive than the carbon-centered radicals.
Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1652–1655, September, 2000. 相似文献
99.
B. L. Tumanskii E. N. Shaposhnikova O. G. Kalina V. V. Bashilov M. N. Nefedova S. P. Solodovnikov N. N. Bubnov V. I. Sokolov 《Russian Chemical Bulletin》2000,49(5):843-846
The influence of structurally different methanofragments attached to [60]fullerene on the spectral parameters of the spin-adducts
of phosphoryl radicals with these compounds was studied by ESR spectroscopy. The main direction of attack of phosphoryl radicals
is the same fullerene hemisphere to which the methanofragment is attached.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya. No. 5, pp. 845–848, May, 2000. 相似文献