Computer Assistance in NMR Studies of Rate Processes

Abstract

In the preceding chapter the discussion has been limited to spectra of molecules with apparently stable configurations, that is, to spin systems for which the rates of intra- and intermolecular exchange of sites of spins are either much larger or much smaller than the differences in magnetic energies under study, expressed on a frequency scale. In molecules undergoing exchange reactions or reorientations, the widths, intensities and positions of lines are functions of the lifetimes of the various reacting or reorienting species, or of the average residence times of spins in particular sites. These variable properties of lines can be observed, if the rates of exchange lie between 10^-2 f and 10² f is the energy difference mentioned above.