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A Comparative 1 H‐ and 13 C‐NMR Study of the Dianion and Dication of Biphenylene
Author(s) -
Benken Rainer,
Finneiser Klaus,
Von Puttkamer Henning,
Günther Harald,
Eliasson Bertil,
Edlund Ulf
Publication year - 1986
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.19860690502
Subject(s) - biphenylene , chemistry , dication , ion , hydrocarbon , ring (chemistry) , nmr spectra database , chemical shift , charge density , quadrupole , spectral line , computational chemistry , atomic physics , organic chemistry , physics , phenylene , quantum mechanics , astronomy , polymer
Biphenylene dianion has been prepared by Li reduction of the parent hydrocarbon. It is stable below −30° and was characterized by its 1 H‐ and 13 C‐NMR spectra. A comparison of these data with those of the dication indicates the existence of ion pairs in the dianion case which are responsible for a different charge distribution. The diamagnetic ring currents of both ions, however, are of comparable magnitude, and both are more diatropic than the parent hydrocarbon. Predictions of the π‐charge‐density effect on 1 H chemical shifts are improved by calculations that use the linear and quadratic electric‐field effect equation instead of the simple Spiesecke ‐ Schneider relation.
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