Produção Nacional
Revisado por pares
The special role of B(C 6 F 5 ) 3 in the single electron reduction of quinones by radicals
2018; Royal Society of Chemistry; Volume: 9; Issue: 41 Linguagem: Inglês
10.1039/c8sc03005g
ISSN2041-6539
AutoresXin Tao, Constantin G. Daniliuc, Robert Knitsch, Michael Ryan Hansen, Hellmut Eckert, Maximilian Lübbesmeyer, Armido Studer, Gerald Kehr, Gerhard Erker,
Tópico(s)Radical Photochemical Reactions
ResumoIn the presence of two molar equiv. of B(C6F5)3p-benzoquinone reacts with persistent radicals TEMPO, trityl or decamethylferrocene by single electron transfer to give doubly O-borylated benzosemiquinone radical anions with TEMPO+, trityl or ferrocenium counter cations. All three [(C6F5)3B]2-semiquinone radical anion salts were characterized by X-ray diffraction. The addition of donor reagent THF or DMSO induced rapid back electron transfer, in the case of the [(C6F5)3B]2-semiquinone radical anion oxoammonium salt giving rise to the formation of the (C6F5)3B-DMSO (or THF) Lewis adduct, p-benzoquinone and the TEMPO radical. The reaction of 9,10-anthraquinone or acenaphthenequinone with either the Gomberg dimer or in 1 : 1 stoichiometry in the presence of two molar equiv. of B(C6F5)3 gave the respective two-fold O-B(C6F5)3 containing 9,10-anthrasemiquinone or acenaphthene-semiquinone radical anion salts with either Ph3C+ or counter cations. These products were also characterized by X-ray diffraction. The salts showed analogous back electron shuttling behavior upon treatment with DMSO. 9,10-Phenanthrenequinone reacted analogously with B(C6F5)3 and the electron rich ferrocene. The [(C6F5)3B]2-9,10-phenanthrene-semiquinone salt was characterized by X-ray diffraction. The radical anions were characterized by ESR spectroscopy.
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