We report the temperature dependence of the specific heat of (CO)(x)C-
60, and the temperature dependence of the lattice parameter, as determ
ined by X-ray powder diffraction. A first-order phase transition and a
glass transition are found to occur at temperatures below the corresp
onding transition temperatures of pure C-60. The transition temperatur
es depend on x. Specific-heat measurements on a sample with x approxim
ate to 0.5 show the orientational ordering transition at T-c = 248.8 K
and the glass transition at T-g = 83.9 K. Contrary to pure C-60, the
temperature dependence of the lattice parameter of (CO)xC(60) (x appro
ximate to 0.67) does not show an anomaly at the glass transition, whic
h is explained by the already expanded lattice of(CO)(x)C-60. The ener
gy difference between major and minor orientations is determined as 19
.1 meV.