Dynamical model for the C5H5 cycles in the C60•2 Fe(C5H5)2 solvate -: art. no. 144206

A model for uniaxial rotation is used in order to calculate the rotational potential for the C5H5 rings in the crystal. The contribution from nonbonded interactions is then compared with intra-molecular bounding forces, showing that the observed equilibrium position of the cycles is due to a combination of crystal packing forces and bonding forces within the molecule. The height of the barriers are also extracted and it confirms that there are two kinds of cycles with specific magnetic and electrical environments. The temperature evolution of the spin-lattice relaxation time is probed by H-1 NMR spectroscopy over the range 54-394 K and is treated with the model proposed for the simulation. One of the two calculated activation energies is observed in the experimental curve; this indicates coupling with one kind of cycle over the studied temperature range.