Reversible Polymerizationin Doped Fullerides UnderPressure: The Case Of C60(Fe(C5H5)2)2.

High-pressure Raman studies have been carried out onsingle crystallineC60(Fc)2nanosheets up to 25.4 GPa. Our resultsshow that the charge transfer between Fc (ferrocene) and C60increases in the low-pressure range. Above 5 GPa, C60molecules start to form a chainlike polymer structure, and thispolymerization is reversible upon decompression, in contrast to thatof pristine C60. The special layered structure of C60(Fc)2restricts the polymerization of C60molecules in some directions and explains the formation of the linearchainlike polymeric structure of the C60lattice underpressure. We suggest that the reversible polymerization is relatedto the increased charge transfer and the overridden steric repulsionof counterions. [ABSTRACT FROM AUTHOR]