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Calculations of the 13 C nuclear screening tensors for coumarin and some methoxycoumarins
Author(s) -
Grigor G. I.,
Webb G. A.
Publication year - 1977
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.1270090806
Subject(s) - coumarin , atomic orbital , excitation , computational chemistry , gauge (firearms) , term (time) , chemistry , atomic physics , physics , materials science , nuclear physics , quantum mechanics , organic chemistry , electron , metallurgy
INDO calculations are reported of the 13 C nuclear screening tensors in coumarin and some of its methoxy derivatives. Calculations based upon a linear combination of gauge dependent atomic orbitals and those using an uncoupled Hartree–Fock approach are described. Comparison with the results of less sophisticated calculations shows that changes in the excitation energies, bond orders and the 〈 r −3 〉 2p term are together responsible for determining the 13 C chemical shifts.