High-pressure behavior of the crystal structure of the fullerene molecular complex with ferrocene C-60 center dot{Fe(C5H5)(2)}(2)

The crystal structure of the molecular complex C-60 center dot{Fe(C5H5)(2)}(2) was studied by single crystal X-ray diffraction (XRD) analysis at pressures up to 5 GPa using the diamond anvil cell (DAC) technique. The XRD data and subsequent structural analysis clearly show that there is no pressure-induced polymerization in fullerene layers in pressure range studied. The reciprocal unit cell volume V-0/V is a smooth and monotonous function of pressure and fits well to the Murnaghan equation of state (V-0/V) (B')= {1 + P center dot(B'/B-0)}, where V-0 is the volume at ambient pressure, B-0=8.7 GPa and B'=10.5 are the bulk modulus and its derivative, respectively. Pressure dependence of the shortest distance between the C5H5 ring of the ferrocene molecule and the center of the nearest fullerene molecule is linear, while the slope changes at 2.2 GPa indicating on the intermolecular interactions crossover. Other relevant parameter, the Fe-C bond lengths of ferrocene, sensitive to iron charge state, gradually increases. This peculiarity can a sign of pressure-induced partial charge transfer between the donor ferrocene and acceptor fullerene molecules.