H. Wenk, W. Sander
Dec 1, 2002
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0
Influential Citations
28
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Journal
European Journal of Organic Chemistry
Abstract
The fluorinated m-didehydrobenzenes 5-H-, 5-deuterio-, 5-(trifluoromethyl)-, 5-(trimethylsilyl)-, and 5-iodo-2,4,6-trifluoro-1,3-didehydrobenzene 6b−6f were generated by UV photolysis of the corresponding 1,3-diiodobenzene derivatives 4b−4f in solid neon at 3 K. The photolysis of 1 proceeds stepwise via the phenyl radical intermediates 5b−5f. The radicals 5 and m-benzynes 6 were identified by comparison of their experimentally measured IR spectra with those produced by DFT calculations. The formation of mono- and diradicals 5 and 6, respectively, is reversible, and annealing of the matrix at 7.5 K results in a decrease in all IR absorptions assigned to the radical products and in back-formation of the diiodobenzenes. The influence of the substituents in the 5-position on the geometries and the electronic structures of the diradicals 6 is discussed. The calculations indicate that the singlet-triplet splittings of the substituted m-benzynes 6b−6f are larger and the C1−C3 distances shorter than those in the parent m-benzyne (C6H4). (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)