REDUCING SUPERMOLECULES TO PSEUDO-ATOMS AND ANIONS - CRYPTATIUM SPECIES AND C-60

As part of our continued interest in the redox properties of macrocyclic and macrobicyclic ligands and their corresponding metal cation complexes, we have recorded the electrochemistry of several cryptands and their cryptates, along with those for the carbon clusters C60 and C70. The electrochemistry of C60 and C70 at low temperature has yielded the first observation of the corresponding hexaanionic forms, C-60(6-) and C-70(6-). These multiple reductions appear to be chemically and electrochemically reversible under the conditions used, so the method has been employed to generate and detect C-60(2-) by ESR spectroscopy. The cryptands and cryptates studied also exhibit multiple ligand-based redox processes and, in some cases, the reduction products are isolated as crystalline materials. The crystal structure of one of these materials, the first CRYPTATIUM species, has been reported. This species is a neutral, expanded-metal type intramolecular ion pair. On a closely related topic, formation of a novel crystalline material from the reductive electrocrystallization of [Ru(bpy)3]Cl2 is reported here for the first time. The latter material is assumed to be [Ru(bpy)3]o.