We have measured the infrared spectra of Cs(4)C(60) in the temperature range 220 - 450 K.
Two anomalies in the low-frequency modes at 270 K and 400 K point to changes in molecular or
crystal structure. The most probable explanation is a rotator phase above 400 K and a fully ordered
phase below 220 K; the intermediate structure is one where molecular Jahn-Teller distortions
compete with crystal field effects