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Nitrogen NMR Spectroscopy

1987; Elsevier BV; Linguagem: Inglês

10.1016/s0066-4103(08)60290-2

2163-6052

M. Witanowski, L. Stefaniak, G. A. Webb,

Various Chemistry Research Topics

This chapter presents a full survey of the nitrogen NMR literature for the period covering from late 1980 to the end of 1983. During these three years, the applications of nitrogen NMR have continued to increase and the number of publications relating to it has burgeoned. Advances have been made in both the experimental and theoretical aspects of the subject during this period. That nitrogen NMR acts as an invaluable structure-determination technique for many chemists and biochemists is due to the extent of the nitrogen chemical shift range. The chapter presents a superficial account of the theoretical background to nuclear shielding and spin-spin coupling interactions. In either case the total nuclear shielding is represented by the summation of diamagnetic terms, which are positive in sign, and negative paramagnetic contributions. Nitrogen shielding assignments may require non-trivial techniques or a combination of various methods in order to obtain unambiguous results. This happens because spin-spin couplings of nitrogen nuclei are often difficult to obtain or are not too informative, particularly in the case of long-range couplings of 15N in unsaturated or aromatic systems.