Electron Oxidation of Aromatic Molecules and Related Delocalized-Electron Solids

摘要

Syntheses for C sub 6 F sub 6 AsF sub 6 and C sub 10 F sub 8 AsF sub 6 were developed. C sub 5 F sub 5 NAsF sub 6 and CF sub 3 C sub 6 F sub 5 AsF sub 6 were prepared from the interaction of O sub 2 AsF sub 6 with pentafluoropyridine and octafluorotoluene. Pyrolysis of C sub 6 F sub 6 AsF sub 6 , C sub 5 F sub 5 NAsF sub 6 and CF sub 3 C sub 6 F sub 5 AsF sub 6 yields an equimolar mixture of the parent fluorocarbon and an isomer-specific cyclohexadiene. A mechanism for this decomposition involving F exp - transfer from anion to cation is discussed. Hydrolysis of C sub 10 F sub 8 AsF sub 6 yields an equimolar mixture of C sub 10 F sub 8 and an isomer-specific quinone C sub 10 F sub 6 O sub 2 . A mechanism involving OH exp - attack on the cation is presented. Benzene reacts with AsF sub 5 to give (C sub 6 H sub 5 ) sub 2 AsF sub 2+ AsF sub 6- , which then reacts quantitatively with CsF to give (C sub 6 H sub 5 ) sub 2 AsF sub 3 and CsAsF sub 6 . Interaction of (C sub 6 H sub 5 ) sub 2 AsF sub 3 with AsF sub 5 reconstitutes the fluoroarsonium salt. Variable temperature exp 19 F NMR studies show phi sub 2 AsF sub 3 to be a rigid trigonal bipyramid, with the phenyl groups in equatorial positions, to 71 exp 0 C. Interaction of benzene with O sub 2 AsF sub 6 or C sub 6 F sub 6 AsF sub 6 yields a mixture of (C sub 6 H sub 5 ) sub 2 AsF sub 2+ AsF sub 6- and a poly(p-phenylene) salt (C sub 6 H sub 4 )/sub x/AsF sub 6 (1.8 < x < 4.4). A mechanism involving initial electron oxidation of benzene to give the radical cation intermediate C sub 6 H sub 6+ AsF sub 6- is proposed. The moderate electrical conductivity of the polyphenylene salt indicates that it is a delocalized-electron solid. Preliminary results on the electron oxidation of naphthalene, anthracene and phenanthrene suggest the formation of AsF sub 6- salts of these aromatics. Interaction of coronene with O sub 2 AsF sub 6 or C sub 6 F sub 6 AsF sub 6 yields a dark-green mixture. The moderate electrical conductivity of the mixture indicates that at least one component in the mixture is a delocalized-electron solid. (ERA citation 05:020962)