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A comparison of classical and quantum‐mechanical ‘ring‐current’ theories
Author(s) -
Rose P. I.
Publication year - 1973
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.1270050405
Subject(s) - ring (chemistry) , quantum , series (stratigraphy) , electromagnetic shielding , phenanthrene , resonance (particle physics) , physics , spectral line , proton , computational chemistry , quantum mechanics , chemistry , nuclear magnetic resonance , atomic physics , organic chemistry , paleontology , biology , astrobiology
Abstract The proton resonance spectra of a series of 2,7‐disubstituted‐4,5‐bis(2‐pyridyl)phenanthrene‐3,6‐diols are examined with emphasis on the shielding effects produced by aromatic ‘ring currents.’ In this series, two pyridine rings are rigidly held less than 3.4 Å apart and with considerable overlap. The ‘ringcurrent’ shieldings found for above‐the‐plane positions are in good agreement with the Johnson‐Bovey theory, whereas a recently proposed quantum‐mechanical theory underestimates the shieldings by a factor of nearly three.