1. Departament de Química, Universitat de Girona, Campus de Montilivi, E-17071 Girona, Spain, Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255, Department of Chemistry, University of Florence, Via della Lastruccia 3, I50019 Sesto Fiorentino, Florence, Italy, and Departament de Cristal·lografia, Mineralogia i Dipòsits Minerals, Universitat de Barcelona, Martí i Franquès, s/n, E-08028 Barcelona, Spain