1. Contribution from the Department of Chemistry, University of Sheffield, Sheffield S3 7HF, United Kingdom, Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 27 Taylor Street, Glasgow G4 0NR, Scotland, Institute for Inorganic and Analytical Chemistry, Frankfurt University, 60438 Frankfurt am Main, Germany, European Synchrotron Radiation Facility, 38042 Grenoble, France, and ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, United Kingdom