1. Contribution from the Laboratoire de Chimie Inorganique et Bioinorganique, Ecole Polytechnique Fédérale de Lausanne, EPFL-BCH, CH-1015 Lausanne, Switzerland; TDA Research, Inc., 12345 West 52nd Avenue, Wheat Ridge, Colorado 80033; Departament de Química Inorgànica, Universitat de Barcelona, Martí i Franquès 1-11, E-08028 Barcelona, Spain; and Department of Chemistry, Center for Nanoscale Science and Technology, Center for Biological and Environmental Nanotechnology, Rice University, Houston, Texas 77251...