1. Department of Inorganic and Analytical Chemistry; University of Geneva; 30 quai E. Ansermet CH-1211 Geneva 4 Switzerland
2. Laboratory of Crystallography; University of Geneva; 24 quai E. Ansermet CH-1211 Geneva 4 Switzerland
3. Department of Physical Chemistry; University of Geneva; 30 quai E. Ansermet CH-1211 Geneva 4 Switzerland
4. Current address: Université Rennes, INSA Rennes, CNRS, ISCR “Institut des Sciences Chimiques de Rennes”; F-35708 Rennes France
5. Centre de Biophysique Moléculaire, CNRS UPR 4301; Rue Charles Sadron F-45071 Orléans Cedex 2 France