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Non‐empirical calculations of NMR indirect carbon–carbon coupling constants. Part 9 —Bicyclobutane‐containing polycycloalkanes
Author(s) -
Krivdin Leonid B.
Publication year - 2004
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1415
Subject(s) - chemistry , moiety , coupling constant , computational chemistry , spin (aerodynamics) , coupling (piping) , carbon 13 nmr , carbon fibers , stereochemistry , thermodynamics , quantum mechanics , physics , materials science , metallurgy , composite number , composite material
13 C 13 C spin–spin coupling constants characterizing the bicyclobutane moiety of seven well‐known bicyclobutane‐containing polycycloalkanes were calculated at the SOPPA level. Benchmark calculations on tricyclopentane and octabisvalene revealed an appropriate level of theory and sufficient quality of basis sets used to perform geometry searches and to calculate spin‐spin coupling constants. Several experimental uncertainties were resolved and a number of interesting couplings were predicted. The most interesting trend observed in this series of polycycloalkanes is the marked increase (decrease in absolute value) of J (C,C) between bridgehead carbons with increase in the puckering angle of the bicyclobutane moiety. This predicts almost zero coupling between bridgehead carbons of tricyclopentane and explains the positive J (C,C) in tetrahedrane in contrast to the negative bridgehead‐bridgehead J (C,C) in bicyclobutane. Copyright © 2004 John Wiley & Sons, Ltd.