Erich Hasler, Aldo Hoermann, Gabriele Persy
Jun 1, 1993
Citations
0
Influential Citations
17
Citations
Journal
Journal of the American Chemical Society
Abstract
The photochemical and thermal reaction paths in the valence isomerization 2,7-dihydro-2,2,7,4-tetra-methylpyrene (1)⇄2,2,7,7-tetramethyldicyclopropa [a,g]pyracene (2) were traced by flash photolysis, optical and ESR spectroscopy, thermal reaction kinetics, and oxygen trapping experiments. The heat evolved in the reaction 2→1 was determined by differential scanning and photoacoustic calorimetry. All reactions connecting 1 and the two geometric isomers of 2 proceed through a common perinaphthadiyl biradical intermediate (b, Scheme I). State-symmetry correlation proved to be a valuable guideline to excited-state reactivity