1. Laboratoire de Physique de la Matière Condensée, Ecole Polytechnique, Institut Polytechnique de Paris, CNRS, Route de Saclay, 91128 Palaiseau, France
2. Department of Inorganic Chemistry, Institute of Chemistry, University of Campinas (Unicamp), R. Monteiro Lobato, 270, 13083-970 Campinas, São Paulo, Brazil