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Pure Appl. Chem., 2001, Vol. 73, No. 11, pp. 1795-1818


NMR nomenclature. Nuclear spin properties and conventions for chemical shifts(IUPAC Recommendations 2001)

Robin K. Harris1*, Edwin D. Becker2, Sonia M. Cabral de Menezes3, Robin Goodfellow4 and Pierre Granger5

1 Department of Chemistry, University of Durham, South Road, Durham, DH1 3LE, UK
2 National Institutes of Health, Bethesda, Maryland 20892-0520, USA
3 PETROBRAS/CENPES/QUÍMICA, Ilha do Fundão, Quadra 7, Cidade Universitária, 21949-900, Rio de Janeiro, R.J., Brazil
4 School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK
5 Institut de Chimie, Université Louis Pasteur de Strasbourg, 1 rue Blaise Pascal, 67008 Strasbourg, CEDEX, France

A unified scale is recommended for reporting the NMR chemical shifts of all nuclei relative to the 1H resonance of tetramethylsilane (TMS). The unified scale is designed to provide a precise ratio, Ξ, of the resonance frequency of a given nuclide to that of the primary reference, the 1H resonance of TMS in dilute solution (volume fraction, φ < 1%) in chloroform. Referencing procedures are discussed, including matters of practical application of the unified scale. Special attention is paid to recommended reference samples, and values of Ξ for secondary references on the unified scale are listed, many of which are the results of new measurements.
Some earlier recommendations relating to the reporting of chemical shifts are endorsed. The chemical shift, δ, is redefined to avoid previous ambiguities but to leave practical usage unchanged. Relations between the unified scale and recently published recommendations for referencing in aqueous solutions (for specific use in biochemical work) are discussed, as well as the special effects of working in the solid state with magic-angle spinning. In all, nine new recommendations relating to chemical shifts are made.
Standardized nuclear spin data are also presented in tabular form for the stable (and some unstable) isotopes of all elements with nonzero quantum numbers. The information given includes quantum numbers, isotopic abundances, magnetic moments, magnetogyric ratios and receptivities, together with quadrupole moments and line-width factors where appropriate.