THE ORIENTATIONAL-ORDERING TRANSITION IN SINGLE-CRYSTALS OF SELECTED C-60 COMPLEXES WITH ORGANIC DONORS FOLLOWED BY INFRARED-SPECTROSCOPY

Investigations of infrared spectra of single crystals of the complex o f fullerene C-60 With dianthracene (DAN) and C-60 grown from CS2 solut ion (clathrate) versus temperature, between 4 and ca. 430 K, have been performed. A phase transition for the complex and the clathrate accom panied by a splitting of the F-1u(4) band into at least two components was detected at temperatures higher than 260 K. The line splitting wa s attributed to C-60 symmetry lowering as a result of suppression of i ts rotation. Phase transitions at 80, 160 and 305 K have been observed for DAN C-60 (C6H6)(3); the nature of the transitions has been sugges ted. (C) 1998 Elsevier Science B.V. All rights reserved.