DISPROPORTIONATION OF RB3C60 BY AMMONIA TO PRODUCE 2 NEW AMMONIATED FULLERIDES

Intercalation of ammonia into the superconductor Rb3C60 results in the short term in the formation of a material best described as quasicrys talline or icosahedrally coordinated glass, When allowed to age and eq uilibrate, this material disproportionates to a mixture of orthorhombi c RbC60 and two new phases whose structures we have determined by comb ined X-ray and neutron powder diffraction. They are a cubic Fm-3m phas e, Rb3C60(ND3)(4.8), and a body-centred orthorhombic Immm phase of com position Rb4C60(ND3)(1.7).