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Interactions between Oxygen Lone‐Pair Orbitals and Double‐Bond π‐Orbitals in β,γ‐Unsaturated, Bicyclic Ketones; a PE‐Spectroscopic Investigation
Author(s) -
Carrupt PierreAlain,
Gabioud Raphy,
Rubello Albino,
Vogel Pierre,
Honegger Evi,
Heiloronner Edgar
Publication year - 1987
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.19870700612
Subject(s) - chemistry , bicyclic molecule , lone pair , atomic orbital , orbital hybridisation , double bond , molecular orbital , ab initio , crystallography , computational chemistry , stereochemistry , valence bond theory , molecule , organic chemistry , physics , quantum mechanics , electron
The HE(Iα) photoelectron (PE) spectra of 2,3,5,6‐tetramethylidene‐2‐bicyclo[2.2.1]heptanone ( 12 ), 5,6‐dimethylidene‐2‐bicyclo[2.2.1]heptanone ( 14 ), 5,6‐dimethylidene‐2‐bicyclo[2.2.2]octanone ( 16 ), and 5,6,7,8‐tetramethylidene‐2‐bicyclo[2.2.2]octanone ( 17 ) have been recorded, Comparison with the PE data of other β,γ‐unsaturated ketones and parent alkenes, and with the result of ab initio STO‐3G calculations, confirm the existence of significant interactions between the oxygen lone‐pair orbital n o and the double‐bond π orbital(s). It is argued that the major contributions to the basis energy shifts and to the cross term between the n o and π orbitals are due to a ‘through‐bond’ mechanism.