B. L. Tumanskii

Trifluoromethylation of [60]- and [70]Fullerene in the Ionization Chamber of a Mass Spectrometer

Abstract Both [60]- and [70]fullerene react with either the Scherer radical (perfluorodiisopropylethylmethyl, C9F19), a mixture of branched perfluorononenes (C9F18, the product of hexafluoropropene trimerization), or β-fluorosulphatotetrafluoroethyldiheptafluoroisopropylmethyl radical (C9F18OSO2F) in the ionization chamber of a mass spectrometer to give the positive parent ions of trifluoromethylation products, the reaction being accompanied by hydrogen addition. The reaction occurs at least partly on the walls of the ionization chamber, by a radical mechanism employing CF3 radicals formed from the radical reactants both thermally and under electron impact; only the latter route occurs with the perfluorononenes.

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 η2-bonded metaIloco mplexes are discussed.

Metal-containing fullerenyl radicals: generation in solution and EPR study

Abstract Photolysis of cis -(CF 3 ) 2 CFHgPt(PPh 3 ) 2 CHCPh 2 in a saturated toluene solution of C 60 has generated the platinum-centered free radical, which adds to C 60 to give a spin-adduct cis -Ph 2 CCHPt(PPh 3 ) 2 C 60 fully characterized by EPR spectroscopy. Phosphorylfullerenyl radicals containing a η 2 -coordinated ML 2 moiety have been prepared, starting from phosphorylfullerenyl radical dimers. The metal complex (η 2 -C 70 )Pd[(+)DIOP] has been shown to undergo the partial rupture of MC bonding as a consequence of the phosphoryl radical attack on the metal atom to give three regioisomers of metal-containing fullerenyl radicals.

EPR Study of Reactivity of Endohedral Metallofullerenes La@C82 and Y@C82

Abstract Reactivity of La@C82 in the mixture with C60 and C70 vs L2pto, phosphoryl radical ∗P(O)(OR)2, and CF3COOH has been studied using EPR spectroscopy. Whereas two former reagents did not change EPR spectrum, treatment with CF3COOH in toluene caused the disappearance of minor octet and a new signal was observed. Similar behaviour was found upon treatment of Y@C82 with CF3COOH. It is interpreted as selective protonation of one isomer of endohedral metallofullerene.

Addition of carbon-centered radicals to C60. Determination of the rate constants by the spin trap method

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.

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.

Heterometallic binuclear complexes involving the mercury—platinum bond as a source of a platinum carbenoid in reactions with fullerene-60

The cleavage of two σ-bonds and the formation of a metallocomplex, (η2-C60)Pt(PPh3)2, occur in a new reaction between fullerene-60 and binuclear heterometallic compounds having a mercury-platinum bond (retro-insertion promoted by C60). One of these,trans- Ph2CHCH2HgPt(PPh3)2Br,1, which contains an electron-donating group at the mercury atom, reacts two orders of magnitude faster thancis-(CF3)2CFHgPt(PPh3)2CH=CPh2,2, which has an electron-withdrawing substituent at mercury. An asymmetrical organomercury compound is the second product of the reaction. The reactants and products have been characterized by spectroscopic data (1H,31P NMR, UV-VIS) and elemental analyses. Compound 2, which is more stable to retro-insertion, gives a Pt-centered free radical upon photolysis. This was used for the free-radical functionalization of C60. The platinumfullerenyl radicalcis-C60Pt(PPh3)2R2 was identified by EPR spectroscopy.

Spectral study of reactions of La@C82 and Y@C82 with amino-containing solvents

A solvent effect on the electronic absorption UV-VIS and ESR spectra of La@C82 and Y@C82 was found. The UV-VIS spectra of La@C82 in pyridine, dimethylformamide, and hexamethylphosphorotriamide are identical with that of the La@C82– anion, which is evidence for La@C82 reduction in these solvents. In amino-containing solvents, the shape of the ESR spectra depends on the temperature and the time of preparation of the solutions. Changes in the ESR spectra of La@C82 and Y@C82 in dimethylformamide are due to functionalization of these compounds upon reduction.

Perfluoro-1,2-di-t-butylvinyl radical stable in an inert medium

Abstract The perfluoro-1,2-di-t-butylvinyl radical has been generated by direct fluorination of perfluorodi-t-butylacetylene or by the addition of the perfluorodi-t-butyl radical to perfluoro-t-butylacetylene in perfluorodiamyl ether. The radical was identified by its ESR spectrum, and appeared to be quite stable in an inert medium.

Addition of Me2·CCN, Me2·CPh, and CCl3CH2·CHPh radicals to fullerene C60

The rate constants for addition of the Me2·CCN, Me2·CPh, and CCl3CH2·CHPh radicals to fullerene C60 at 22 °C were determined by ESR spectroscopy using spin trapping technique.