We report high-pressure C-13 NMR spin-lattice relaxation times for C-6
0 at 295 K. A discontinuity in T-1 is observed at 2.7 +/- 0.2 kbar and
is attributed to the face-centered cubic to simple cubic structural p
hase transition. The activation volume for molecular reorientation in
the fee phase is 3.5 +/- cm(3)/mol.