Carbon-13 NMR satellite

In an NMR spectrum the presence of 1% of the NMR active carbon-13 species will cause coupling. This will split 1% of the peak into a doublet. These are called satellites as they small and are around the main non-coupled peak like little shoulder peaks.

This is usually seen in the 1H-NMR, as small shoulder peaks, but can be seen in 19F or 31P NMR, as long as these atoms are on a carbon atom that is the spectrum is not 13C-decoupled (usually the case).

Uses

Can be used to obtain structural information, due to de-symmetry as compared to 99% of molecule where C atom is 12-C.

For example, you can not tell if stilbene Ph-=-Ph is cis- or trans- bonded just by looking at the 1H NMR of the protons on the double bond, without reference to any other material, as they do not couple (molecule is symmetric). However 1% of molecules will have a 13C atom on one of these double bond carbons. The protons on these atoms will be 13C coupled and give a doublet. However, this molecule is not symmetric and the protons on the double bond couple. The coupling in the satellite peaks (i.e. a double of doublets i.e. one 13C coupling and one cis-/trans- 1H coupling) in the double bond of Ph-=-Ph will tell you if it is cis- or trans- bonded by the size of the J splitting in the 1H constant.

ee also

* not to be confused with side band spinning effect,
*1H NMR
*13C NMR

References

* NMR SATELLITES AS A PROBE FOR CHEMICAL INVESTIGATIONS SHIzuo FUJIWARA, Yogi ARATA, HIR0sHI OZAWA and MASAYUKI KuruGI Department of Chemistry, The University of Tokyo, Japan [http://old.iupac.org/publications/pac/1972/pdf/3201x0117.pdf]
* Y. Ogimura, S. Fujiwara and K. Nagashima, Chemical Instrumentation 1, 21 (1968); S. Fujiwara, Y. Yano and K. Nagishima, Chemical Instrumentation 2, 103 (1969); S. Fujiwara, Magnetic Resonance, ed., C. K. Coogan et a!., Plenum Press, New York (1970).
* H. Ozawa, Y. Arata and S. Fujiwara, J. Chem. Phys., to be published.
* S. Forsén and R. A. Hoffman, J. Chem. Phys. 40, 1189 (1964); R. A. Hoffman and S. Forsén, J. Chem. Phys. 45, 2049 (1966).
* N. Bloembergen and R. V. Pound, Phys. Rev. 95, 8 (1954); S. Bloom, J. App!. Phys. 28, 800 (1957).
* A. O. Niel, Phys. Rev. 77, 789 (1950).
* Geometry determination of tetrasubstituted stilbenes by proton NMR spectroscopy, Viviana S. Fluxáa, Titus A. Jennya and Christian G. Bochet, Tetrahedron Letters, Volume 46, Issue 22, 30 May 2005, Pages 3793-3795


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