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  Home > JCE Print > Journal of Chemical Education > Issues > 2002  > February  >
In the Laboratory
An ABMX Spin System Study: From Experimental to Calculated Spectra
Christine Cordier
ITODYS, Université Paris, Paris, France

René Thouvenot, Hani Amouri, and Michel Gruselle
Laboratoire de Chimie Inorganique et Matériaux Moléculaires, Université Paris, Paris, France


Cover
February 2002
Vol. 79 No. 2
p. 234

Abstract
The 1H NMR spectrum of the stable organometallic cation [Co2(CO)5(m-HCtriple bondCCH2-PF2-CH2-PF2]+ displays both ABX and ABMX subspectra. The experimental analysis of these spin systems is carried out by means of a set of 1H and 31P NMR spectra. Techniques of selective decoupling of each of the phosphorus nuclei and 31P broad-band decoupling jointly to proton selective decouplings drastically simplify the examination of such subspectra and allow an unambiguous assignment of their signals. In addition, 1H-1H coupling constants are estimated. The theoretical investigation of spin systems containing nuclei strongly coupled is intended for students of a graduate level spectroscopy course. In this work, the quantum mechanical treatment of the ABX and ABMX models is developed. With this information and the experimental coupling constants, students are able to generate a calculated ABX or ABMX subspectrum. The spectral simulation with appropriate software (such as gNMR) allows students to confirm the signal assignment for the 1H spectrum and to compare the calculated coupling constants with the experimental data.
Supplement
Nine FID data sets corresponding to the spectra given in Figures 1 and 2 are available.

Note: The FIDs can be processed either on a Bruker spectrometer that is suitable to read data acquired on an AC spectrometer or by any NMR program that usually treats data in the Bruker format.


*  Contents JCE2002p0234W folder containing FIDs as Bruker format and Fourier transformed spectra.
*  Download
JCE2002p0234W.zip

JCE2002p0234W.sit

More Information
*  Citation
Cordier, Christine; Thouvenot, René ; Amouri, Hani; Gruselle, Michel. J. Chem. Educ. 2002 79 234.
*  Keywords
Computer Assisted Instruction; Graduate Education / Research; NMR Spectrometry; Quantum Chemistry; Statistics / Data Analysis; Theoretical Chemistry
*  History
Created:
Last Updated:
January 2, 2002
March 16, 2005
  Home > JCE Print > Journal of Chemical Education > Issues > 2002  > February  > Page 234


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