1. Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, U.K., Department of Chemistry, University of Reading, Whiteknights, Reading RG6 2AD, U.K., Department of Chemistry, Loughborough University of Technology, Loughborough, Leicestershire LE11 3TU, U.K., and Kodak Limited, Headstone Drive, Harrow, Middlesex HA1 4TY, U.K.