Thomas P. Fehlner is Emeritus Grace Rupley Professor of Chemistry at the University of Notre Dame, Indiana. He received his PhD in physical chemistry from the Johns Hopkins University, Maryland, in 1963. His current research interests include the systematic chemistry of metalloboranes and an application of mixed valence metal chemistry to molecular electronics. Jean-François Halet is a Director of Research in the chemical sciences laboratory at the Centre National de la Recherche Scientifique and the University of Rennes 1, France. He received his PhD in physical chemistry in 1984 from the University Pierre-et-Marie Curie, Paris. His research interests focus on understanding the chemical bond in transition metal inorganic chemistry using different quantum chemical computational tools. In particular, he attempts to analyse structural similarities between molecular and solid state compounds. Jean-Yves Saillard is a professor of chemistry in the chemical sciences laboratory at the University of Rennes 1, Rennes, France, and in the Institut Universitaire de France. He received his PhD in chemistry in 1974 from the University of Rennes 1, Rennes. His current research interests include the rationalization of structures; and the reactivity and physical properties of inorganic compounds, particularly organometallic complexes, clusters and solid-state compounds.