Gr. Jones et al., LONG-DISTANCE EFFECT ON ONE-BOND C-C SCALAR COUPLINGS UPON INTRODUCTION OF A DOUBLE-BOND IN BICYCLIC SYSTEMS, Helvetica Chimica Acta, 80(1), 1997, pp. 59-64
Anomalous variations of one-bond C-C scalar coupling constants are obs
erved in going from trinorbornane-to trinorbornene-like structures. Mo
st notably, a IO-Hz increase is observed in the coupling constant invo
lving the C-atoms of the ethano branch facing the C=C bond. An effect
of about half the size is characteristic of higher homologues (bicyclo
[2.2.2]octenes), but no such effect is observed for monocyclic molecul
es.