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The Photolysis of Tricyclo[4.2.1.0 2,5 ]nonadiene: Support of a Doughert ‘type N’ mechanism from photoelectron spectroscopical studies
Author(s) -
Haselbach Edwin,
Eberbach Wolfgang
Publication year - 1973
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.19730560614
Subject(s) - chemistry , photodissociation , excited state , bond cleavage , ground state , molecule , computational chemistry , electron , cleavage (geology) , photochemistry , stereochemistry , atomic physics , organic chemistry , catalysis , physics , geotechnical engineering , quantum mechanics , fracture (geology) , engineering
In earlier work on the photolysis of derivatives of tricyclo[4.2.1.0 2,5 ]nonadiene (I), the intermediacy of a biallyl‐like structure has been postulated which is formed by C 1 ‐C 2 bond cleavage of I in its first excited state. This mechanism is now supported by the results of photoelectron spectroscopical studies on I and its two dihydroderivatives. Further support is gained from the theoretically calculated Ehrenson C 1 ‐C 2 ‐bond indices for the ground and the first excited state of these molecules. While the results for I in principle can be rationalized on the (one‐electron) basis of ‘through bond’ interaction between the two π‐bonds, the absence of C 1 ‐C 2 photocleavage for a substituted tricyclo[4.2.2.0 2,5 ]decadiene also requires consideration of an (all‐electron) thermochemical driving force.