TESTING THE T1 METHOD - A COMPARISON OF T1(MIN) AND STRUCTURAL DATA

For a series of mononuclear polyhydrides for which both structural and relaxation data are available, there is good agreement between the calculated and observed T1(min) values. This substantiates the two assumptions made in the calculations, that the solid-state structure is maintained in solution and that dipole-dipole (DD) relaxation is dominant. There do not seem to be significant contributions from the spin rotation (SR), chemical shift anisotropy (CSA), or scalar (SC) mechanisms in the cases studied. The effects of thermal excursions from the equilibrium positions and DD relaxation from the 31P nuclei of the ligands are shown to be relatively small. The implications for the interpretation of T1, data are discussed. The binuclear complexes Re2H8L4 relax significantly faster than predicted from the structure by the DD equations. Further study is needed to identify the origin of the discrepancy. © 1990, American Chemical Society. All rights reserved.