Nuclear magnetic resonance spectroscopy chemical shift reagents

Cockerill AF, Davies GLO, Harden RC and Rackham DM (1973) Lanthanide shift reagents for nuclear magnetic resonance spectroscopy. Chemical Reviews 73 553-588. 

Nuclear Magnetic Resonance Spectroscopy.—As noted above, conformational analysis of bicyclo[3.3.1]nonanes is still a topic of considerable interest. A variable-temperature n.m.r. analysis now provides the first case in which the boat-chair-chair-boat equilibrium is directly observed in the amines (17) and (18). In a related case, re-examination of the acetal (19) suggests that the preferred conformation involves a chair carbocyclic ring and a boat heterocyclic ring. This conclusion was made by n.m.r. analysis, using lanthanide shift reagents, by a study of nuclear Overhauser effects, and by measurement of relaxation times of protons. Details have been reported for other 3-azabicyclo[3.3.1]nonanes, and the non-additivity of substituent effects on chemical shifts in 9-thiabicyclo[3.3.1]non-2-enes has been analysed. Both and n.m.r. data have been reported for a series of 9-borabicyclo[3.3.1]non-anes and their pyridine complexes. 

Since the 1950s, nuclear magnetic resonance (NMR) has found wide application in the solution of chemical problems, including numerous applications in the field of Grignard reagents. Chemical shift and spin-spin-coupling data enable the chemist to determine the location of magnetically active nuclei in a molecule of interest, and to obtain preliminary structural information often not readily deducible by other methods of spectroscopy. 

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