1. Laboratory of Molecular Magnetism (LaMM) Department of Chemistry and INSTM Università degli Studi di Firenze Via della Lastruccia, 3 50019 Sesto Fiorentino Italy
2. Institut Parisien de Chimie Moléculaire, UMR CNRS 8232 Department of Chemistry Université Pierre et Marie Curie, Paris Case 42, IPCM, UPMC 75252 Paris Cedex 05 France