Premium
Photoenolisation. X. . An ab initio SCF‐CI study
Author(s) -
Sevin A.,
Bigot B.,
Pfau M.
Publication year - 1979
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.19790620309
Subject(s) - chemistry , steric effects , ab initio , singlet state , relaxation (psychology) , computational chemistry , ab initio quantum chemistry methods , triplet state , crystallography , stereochemistry , molecule , excited state , atomic physics , organic chemistry , psychology , social psychology , physics
The processes involved in photoenolisations are theoretically simulated by an ab initio SCF‐CI method, using cis ‐2‐butenal as a prototype structure. The prominent role of the hydroxyl group conformation in the resulting transient ( 2a ) is emphasized; its rotation ‘out of the reaction site’ allows the next reaction paths to proceed exothermally. The equilibration of the different types of twisted biradicals in the triplet manifold, which only involves a low energy barrier, is thus possible, populating in quite equal weights the precursors of both E ‐ and Z ‐dienols. In the singlet state, the formation of the Z‐isomer is expected to be kinetically dominant. An examination of the role of the substituents suggests that, in related systems, the steric crowding induces important structural relaxation of the dienol geometries.