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The Laticyclic [2 + 2 + 2] Conjugation: PE and UV Spectroscopical Investigation of the Interaction Between Three Parallel π Bonds
Author(s) -
Martin HansDieter,
Mayer Bernhard,
Hünig Siegfried,
Prokschy Frank,
Schmitt Michael,
Peters Karl,
Schnering Hans Georg Von
Publication year - 1987
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19871200211
Subject(s) - chemistry , mndo , reactivity (psychology) , cycloaddition , double bond , computational chemistry , photochemistry , crystallography , stereochemistry , molecule , polymer chemistry , organic chemistry , medicine , alternative medicine , pathology , catalysis
Azo compound 1 contains three parallel π bonds which can give rise to laticyclic [2 + 2 + 2] conjugation. Experimental evidence for that is obtained from photoelectron spectra of 1 and the related compounds 2, 3 and 5 . Geometry optimizations by means of the semiempirical MNDO method predicts a smaller distance (by 7 pm) for d (π NN –η 5 CC ) than for d (π NN –η 6 CC ) which is confirmed by X‐ray structure determination. The consequences of this laticyclic conjugation for the photochemical reactivity are investigated, and reasons are given for the preferential cycloaddition of the azo group to the η 5 CC double bond.