14N nuclear magnetic resonance study of the rotation of acetonitrile in n-alkanes

14N linewidths have been measured for acetonitrile in several n-alkane solutions at variable temperatures. Unlike previously reported results on adamantane in the same solvents, the correlation time for reorientation of the major axis of acetonitrile is linearly related to the solvent viscosity function η/T. The slope, i.e., Kivelson’s κ parameter, decreases as the size of the solvent increases. Moreover, unlike the activation for the reorientation of spherical adamantane which remains constant as the size of the solvent increases, that of acetonitrile increases.