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Interproton coupling over dual vicinal and homoallylic paths in 4‐membered rings
Author(s) -
Barfield Michael,
Abia Augustine A.
Publication year - 1980
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270140515
Subject(s) - vicinal , cyclobutene , series (stratigraphy) , chemistry , molecule , sign (mathematics) , coupling (piping) , stereochemistry , computational chemistry , crystallography , materials science , mathematics , ring (chemistry) , organic chemistry , paleontology , mathematical analysis , metallurgy , biology
Abstract A study is presented of cis and trans HH coupling over dual vicinal (HCCH) and homoallylic/interbenzylic/interbenzylic (HCCCCH) paths in the series of molecules cyclobutene and benzocyclobutanes, and a series of dihydrocyclobutacenaphthylenes. Both the experimental and calculated molecular orbital results for these molecules increase in magnitude as the π‐bond order of the homoallylic (interbenzylic) path decreases . These trends appear to be consistent only with homoallylic (interbenzylic) coupling contributions of negative sign. At least qualitatively, these trends can be rationalized in terms of the increase in positive contributions associated with the π→π* transitions as the energy denominators decrease in the series.