Ab initio MO calculations and 17O NMR at natural abundance of para-substituted acetophenones

Brownlee, R. T. C., Sadek, M. and Craik, D. J. (1983) Ab initio MO calculations and 17O NMR at natural abundance of para-substituted acetophenones. Organic Magnetic Resonance, 21 10: 616-620.


Author Brownlee, R. T. C.
Sadek, M.
Craik, D. J.
Title Ab initio MO calculations and 17O NMR at natural abundance of para-substituted acetophenones
Formatted title Ab initio MO calculations and 17O NMR at natural abundance of para-substituted acetophenones
Journal name Organic Magnetic Resonance
Publication date 1983
Sub-type Article
DOI 10.1002/omr.1270211005
Volume number 21
Issue number 10
ISSN 0030-4921
Start page 616
End page 620
Total pages 5
Place of publication West Sussex, United Kingdom
Publisher John Wiley & Sons
Language eng
Formatted abstract 17O NMR chemical shifts and calculated (ab initio MO theory) electron densities are reported for a series of para-substituted acetophenones, X[BOND]C4H6[BOND]COCH3, where X = NH2, OCH3, F, Cl, CH3, H, COCH3, CN, NO2. The 17O shifts are very sensitive to the para substituent and cover a range of some 51 ppm. Donors induce upfield shifts and acceptors downfield shifts. The substituent chemical shifts (SCS) correlate precisely with σI and σR+ using the Dual Substituent Parameter (DSP) method. The derived transmission coefficients ρI and ρR indicate that polar and resonance mechanisms contribute approximately equally to the observed substituent effects. The shifts also correlate well with calculated π-electron densities (slope = 1500 ppm per electron) confirming their electronic origin. λmath image values are also reported, and the role of the average excitation energy, ΔE, in determining 17O SCS values is discussed. It is concluded that variations in ΔE are minor and that the local Δ-electron density is the dominant feature controlling 17O SCS values.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article
Collection: Institute for Molecular Bioscience - Publications
 
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