The Kinetics of Intramolecular Reactions from Relaxation Time Measurements

Analysis of spin‐lattice relaxation (T1) provides alternatives to the standard line shape procedures for the investigation of intramolecular reactions; furthermore it expands the NMR range at both the high and the low energy barrier limits. Dipole‐dipole‐ and quadrupole‐relaxation times are sensitive to very rapid processes such as methyl rotation. Analysis of relaxation in the rotating frame(T1ρ) provides kinetics for many sorts of processes, particularly those in the dynamic range that is too rapid for line shape methods. Saturation transfer and the coalescence of relaxation times at high temperatures can be used to measure high energy barriers. The scope and limitations of these methods are described. An insight into very rapid intramolecular processes, e.g. the rotation of methyl groups, is possible by measurement of dipole‐dipole and quadrupole relaxation times. Spin‐lattice relaxation provides an alternative to the standard line‐shape analyses. Furthermore it expands the NMR range at both the high and the low energy barrier limits.