College Park, Maryland      June 6 - 10 , 2004

MP42: The Solvation of Fulleride C605- Anions in Potassium-Ammonia Solutions

C. A. Howard (Department of Physics & Astronomy University College London, UK; Rutherford Appleton Laboratory, UK), J. C. Wasse, N. T. Skipper, H. Thompson (Department of Physics & Astronomy University College London, UK)

Investigation of fulleride C60 anions in solution is very important, for example, in the applications of fullerene purification and separation; the manipulation of fullerenes and their derivatives and for studying isolated fulleride anions. C60 can be sequentially reduced in metal ammonia solutions to form high concentrations solvated C60n- (n=1-5) anions [1]

This poster describes the results of new high resolution neutron diffraction studies of C60K5(NH3)250 solutions taken on SANDALS at the ISIS facility. Second order isotopic substitution of deuterium (D) for hydrogen (H), used together with Empirical Potential Structure Refinement (EPSR) provides us with a detailed picture of the structure in these liquids [2]. We find a highly developed solvent structure: the C605- anion is strongly solvated by approximately 45 ammonia molecules, located around 7 from the centre of the fulleride with a second solvation shell present around this. These molecules direct one of their hydrogen atoms towards the centre of a fulleride ion. This strong solvation shells permit attainment of high concentrations of solvent isolated fulleride ions. As well as being interesting from the fundamental standpoint, our results demonstrate that wide angle neutron techniques can be used to investigate the order found around large ions in a polar solvent.

[1] Fullagar, W. K. et al J. Chem. Soc., Chem. Comm. 6, 525-527 (1993)
[2] Soper, Mol. Phys. 99, 1503-1516 (2001)

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