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[2+2]‐Cycloadditionen und ‐Cycloreversionen in Radikalanionen. Eine ESR.‐spektroskopische Beschreibung am Beispiel 2,2′‐disubstituierter Biphenyle
Author(s) -
Müllen Klaus,
Huber Walter
Publication year - 1978
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19780610414
Subject(s) - chemistry , cyclobutane , cycloaddition , reactivity (psychology) , diradical , spin density , photochemistry , cleavage (geology) , medicinal chemistry , spectroscopy , stereochemistry , organic chemistry , singlet state , ring (chemistry) , catalysis , excited state , medicine , alternative medicine , geotechnical engineering , pathology , quantum mechanics , fracture (geology) , nuclear physics , engineering , condensed matter physics , physics
[2+2]‐Cycloadditions and ‐cycloreversions in radical anions. An ESR. spectroscopic study for 2,2′‐disubstituted diphenyl derivatives The radical anions derived from the polycyclic olefins 1, 2 and 3 are shown by ESR. spectroscopy to undergo [ π 2+ π 2]‐cycloaddition reactions even at low temperatures. Similarly, facile cleavage by [ σ 2+ σ 2]‐cycloreversion processes is observed for the radical anions of the corresponding cyclobutane species. This reactivity, which is in marked contrast with the thermal stability of the neutral parent compounds, is discussed taking into account the molecular geometry and the spin density distribution.