2H nuclear magnetic relaxation study of the rotation of adamantane in n-alkanes

Deuteron spin–lattice relaxation time has been measured for adamantane-d1 in several n-alkane solutions at variable temperature. It is found that solvent viscosity plays only a minor role in adamantane reorientation. This latter involves an activated Arrhenius process with a solvent-independent activation energy (1.3 kcal/mole in the 183–423 °K temperature range). It follows that adamantane rotation is mainly governed by microscopic collisional motions rather than by collective hydrodynamic effects and can be pictured by the concept of transient solvent cavities in which the solvent molecule reorients.