Homolytic reactive mass spectrometry of fullerenes: interaction of C60 and C70 with organo- and organoelement mercurials in the electron impact ion source of a mass spectrometer; EPR, CIDEP, and MS studies of several analogous reactions of C60 performed in solution

Yury I Lyakhovetsky; Elena A Shilova; Vasily V Bashilov; Viatcheslav I Sokolov; Yuri S Nekrasov; Boris L Tumanskii

doi:10.1021/jp906058q

Homolytic reactive mass spectrometry of fullerenes: interaction of C60 and C70 with organo- and organoelement mercurials in the electron impact ion source of a mass spectrometer; EPR, CIDEP, and MS studies of several analogous reactions of C60 performed in solution

J Phys Chem A. 2009 Dec 10;113(49):13700-10. doi: 10.1021/jp906058q.

Authors

Yury I Lyakhovetsky¹, Elena A Shilova, Vasily V Bashilov, Viatcheslav I Sokolov, Yuri S Nekrasov, Boris L Tumanskii

Affiliation

¹ A. N. Nesmeyanov Institute of Organoelement Compounds of the Russian Academy of Sciences, 28 Vavilov Str, 119991 GSP-1 Moscow V-334, Russia. yulyakh@ineos.ac.ru

PMID: 19916539
DOI: 10.1021/jp906058q

Abstract

Interaction of C(60) with organo- and organoelement mercurials (CF(3)HgBr, PhHgBr, p-CH(3)C(6)H(4)HgBr, p-CH(3)OC(6)H(4)HgCl, CF(3)HgPh, Ph(2)Hg, (o-carborane-9-yl)(2)Hg, (m-carborane-9-yl)(2)Hg, (p-carborane-9-yl)(2)Hg, and (m-carborane-9-yl)HgCl) in the ionization chamber (IC) of the electron impact (EI) ion source of a mass spectrometer at 250-300 degrees C results in the transfer of the corresponding organic or organoelement radicals from the mercurials to the fullerene. Some of the processes are accompanied by hydrogen addition. C(70) reacts with Ph(2)Hg and (o-carborane-9-yl)(2)Hg at 300 degrees C in a similar fashion. A homolytic reaction path is considered for the reactions. It suggests both the thermal and EI initiated homolytic dissociation of the mercurials to the intermediate organic or organoelement radicals followed by their interaction with the fullerenes at the metallic walls of the IC. When EI is involved, the dissociation is supposed to occur via superexcited states (the excited states with the electronic excitation energies higher than the first ionization potentials) of the mercury reagents, with possible contribution of the process proceeding via their molecular ions. In line with the results obtained in the IC, C(60) reacts with Ph(2)Hg and (o-carborane-9-yl)(2)Hg under UV-irradiation in benzene and toluene solutions to furnish phenyl and carboranyl derivatives of the fullerene, respectively, some also containing the acquired hydrogen atoms. EPR monitoring of the processes has shown the formation of phenylfullerenyl and o-carborane-9-yl-fullerenyl radicals. g-Factors and hyperfine coupling (hfc) constants with (10)B, (11)B, and (13)C nuclei of both the latter and m-carborane-9-yl-fullerenyl radical formed in the reaction of C(60) with (m-carborane-9-yl)(2)Hg have been determined by the special EPR studies. The unusually great chemically induced dynamic electron polarization (CIDEP) of the latter radical where even the (13)C satellite lines are polarized has been observed and is discussed in terms of both radical-triplet-pair and radical-pair mechanisms. The similar CIDEP effect is also intrinsic to the o-carborane-9-yl-fullerenyl radical obtained under the same conditions. The analogous transfer of the carboranyl radicals from (o-carborane-9-yl)(2)Hg to C(60) occurs when their mixture is boiled in (t)BuPh for 10-15 h.