Hydrogen radical/molecule reactions in the negative ion mass spectrometry of dicyano-methane derivatives of 9-fluorenone and benzophenone

Homolytic reactive mass spectrometry of fullerenes: peculiarities of the reactions of C60 with aromatic compounds in the ionization chambers of mass spectrometers and in solution

C60 reacted with PhH, PhCl, BnH, BnNH2, and o-C2H2B10H10 in the electron impact (EI) ion source of a mass spectrometer at 300 °C forming phenyl, benzyl, and o-carboranyl adducts, respectively, stabilized by hydrogen addition and loss. Besides, the additions to C60 of methyl and phenyl radicals for toluene, and a phenyl radical for benzylamine were observed. A homolytic reaction mechanism was suggested involving the reaction of the radicals formed from the aromatics under EI with C60 at the ionization chamber walls. While the ion/molecule reaction of C60 with benzene performed by Sun et al. under chemical ionization conditions at 200 °C afforded the complex C60•PhH(+•), quite a different isomer, HC60Ph(+•), was detected in the present study as a sequence of the different reaction mechanisms. C60 also reacted with benzyl bromide in the laser desorption/ionization (LDI) source of a mass spectrometer to give C60CPh(+). Phenyl and benzyl derivatives of C60 were found, respectively, when the reactions of the fullerene with PhCl, BnH, and BnBr were performed in solution under ultra violet irradiation. For the reaction with toluene, the strong chemically induced dynamic electron polarization of the intermediate benzylfullerenyl radical with the reverse phase effect was found. The coincidence of the results of the mass spectrometry and solution reactions of C60 with aromatics, even though incomplete, additionally supports the hypothesis, formulated earlier, that the former results can predict the latter ones to a significant extent and shows that this conclusion is valid for both EI and LDI initiated reactions in mass spectrometers.

Homolytic reactive mass spectrometry of fullerenes: interaction of C60 and C70 with ketones in the electron impact ion source of a mass spectrometer and the comparison of results with those of photochemical reactions of C60 with several ketones in solution

Our previous investigations showed that homolytic reactions of C(60) with a number of perfluoroorganic and organomercury(II) compounds occurring under electron impact (EI) in the ionization chamber (IC) of a mass spectrometer could predict the reactivity of C(60) towards these compounds in solution or solid state. To expand the scope of this statement, C(60) and C(70) have been reacted with ketones RCOR(1), where R and R(1) are alkyl, aryl, benzyl, and CF(3), in an IC under EI to yield products of the addition of R(·) and R(1)(·) radicals to the fullerenes, paramagnetic ones being stabilized by hydrogen addition and loss. Experimental evidence in support of a mechanism involving homolytic dissociation of ketone molecules via superexcited states to afford these radicals that react with the fullerenes at the IC surface has been obtained. As anticipated, the reactions between C(60) and several ketones conducted in solution under UV irradiation have afforded Me-, Ph-, and CF(3)-derivatives of C(60). However, some other products have been identified by mass spectrometry and their formation is reasonably explained. When decalin has been employed as a solvent, decalinyl derivatives of the fullerene have been found among the products and the (9-decalinyl)fullerenyl radical has been registered by EPR. Thus, incomplete but reasonable conformity of the results of the reactions of fullerenes with ketones in an IC under EI with those of the reactions of the same reagents in solution under UV irradiation has been demonstrated, and the former results can predict the latter ones to a reasonable extent.

Electron ionization (EI) mass spectra of exo-endo double-bond isomers of polycyano "push-pull" pentadienes derived from cycloalkylidene malonic acid derivatives

The title compounds, which exist in solutions as mixtures of exo/endo double bond isomers due to the "push-pull" effect of the electron-donating and electron-withdrawing substituents, were studied by mass-spectrometric methods. Their fragmentation routes under electron impact were established and confirmed by metastable ion analysis and accurate mass measurements. The results demonstrated that the relative amounts of exo/endo isomeric molecular ions are in close agreement with the isomeric ratios observed in solutions by the NMR, although the mass spectra of the tetracyano derivatives indicated a small fraction of molecular ions existing in the endo form, which could not be detected in solution by the NMR methods.