Sterically Hindered Free-Radicals .22. Dimerization and Epr Spectroscopy of Indanedionyl and 9-Acylfluorenyl Radicals

 
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1994 (EN)
Sterically Hindered Free-Radicals .22. Dimerization and Epr Spectroscopy of Indanedionyl and 9-Acylfluorenyl Radicals (EN)

Harnack, C. (EN)

Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας (EL)
Harnack, C. (EN)

2-Phenylindanedionyl radicals 5a, their p- and o-monosubstituted derivatives and related compounds 5b-h recombine by C-C bond formation giving 6a-h. In contrast, o-substituted derivatives 5i-k and the 2-tert-butylindanedionyl radicals 5I react to give the enol ethers 10a-d by C-O coupling. The EPR data indicate that the substituents are more bulky in 5i-I than in 5a-h. From the proton splitting constants it is concluded that 5a is planar and 5h nearly planar (twist angle of the phenyl group ca. 30-degrees). The phenyl group in 5i is twisted considerably with an angle of about 50-degrees. The g values of 5i-k are larger than those of 5a-h indicating a higher spin density in the carbonyl groups. 9-Acylfluorenyl radicals 12b-c, representing the planar conformations of diarylmethyl radicals 1 c, d, give no enol ethers like 4, but recombine by C-C bond formation yielding 13b-c. Their g values indicate that the acyl groups are twisted out of the radical plane. (EN)

triphenylmethyl radicals (EN)

Πανεπιστήμιο Ιωαννίνων (EL)
University of Ioannina (EN)

Journal of the Chemical Society-Perkin Transactions 2 (EN)

English

1994

<Go to ISI>://A1994NQ34100021

Royal Society of Chemistry (EN)



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