1. Department of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K., Department of Chemistry and INSTM Unit, “La Sapienza”, University of Rome, Italy, ISNM-CNR sez. Roma La Sapienza and Laboratorio TASC-INFM-CNR, Trieste, Italy, STFC Daresbury Laboratory, Daresbury, Warrington WA4 4AD, U.K., and Department of Physics, Manchester University, Manchester M13 9PL, U.K.