PRESSURE-TUNING VIBRATIONAL SPECTROSCOPIC STUDY OF (ETA(5)-C5H5)CO(C64H4) - CAN ENDOHEDRAL FULLERENES BE FORMED UNDER PRESSURE

The infrared and Raman spectra of the Co(III)-fullerene complex, CpCo( C64H4) (Cp = eta(5)-C5H5), have been examined under high external pres sures (up to similar to 45 kbar) with the aid of a diamond-anvil cell. The values of the pressure dependencies (dv/dP) of the vibrational mo des are quite normal and range from 0.11-0.58 cm(-1) kbar(-1). Althoug h only limited data were obtained for the bis-fulleroid, C64H4, the vi brations of the organometallic derivative are, in general, more pressu re sensitive than are those of the bis-fulleroid. While there is no ev idence for the formation of an endohedral fullerene throughout the pre ssure range investigated, there is a reversible structural change occu rring in the 8.8-13.1 kbar range, most probably associated with rotati on of the Cp ligand about the Cp-Co bond. (C) 1998 Elsevier Science B. V.