Crystal Structure of Endohedral Metallofullerene La@C₈₂

Abstract

Since the success of synthesis the molecular structure of the endohedral metallofullerene is a most interesting subject in relation to the electronic state of metal and carbon cage. Highquality crystals of endohedral metallofullerene La@C82 have been synthesized by the arc discharge and HPLC method. The x-ray powder diffraction and the precession photograph of a tiny single crystal have revealed the cubic structure with the space group I4̄3d and the lattice constant a_o = 25.72 ± 0.007 Å at room temperature. The structure is characterized by the molecular arrangement in which the molecules align in the [ 111 ] direction with the molecular axis orienting in the same [ 111 ] direction; this structure suggests the existence of a dipole interaction between the molecules. The metal position in the cage is also discussed on the basis of an ellipsoidal model of molecule.