The chemistry of mixed-valence complexes joins that of molecular electronics in the quantum cellular automata (QCA) paradigm, a concept which has been demonstrated to be a possible alternative to the transistor-based technology, in which binary information is encoded in the configuration of charge among redox-active molecular sites. Indeed, the simplest molecular QCA cell is a symmetric mixed-valence system in which the binary states are represented by the location of a mobile electron at one center or the other. Experimental and theoretical efforts have recently been devoted to molecular mixed-valence organometallic systems containing four metal centers as candidates for QCAs. Properties of specific examples based on recently synthesized and hypothetical tetrametallic molecules will theoretically be analyzed and discussed with the aid of DFT calculations.
Jean-François Halet received his D.Phil. degree in Chemical Physics from the University Pierre-et-Marie Curie (Paris) in 1984 and his D.Sc. degree in Chemistry from the University of Rennes in 1990. He joined the Centre National de la Recherche Scientifique (CNRS) as researcher at Rennes, France in 1984. After postdoctoral studies with D. M. P. Mingos, FRS, at Oxford University (UK) and the Nobel Laureate R. Hoffmann at Cornell University (USA) in 1986-1988, he came back to Rennes where he is currently Research Director at CNRS since 1997. He was a Distinguished Visiting Scholar at the University of Adelaide in 1997 and held Visiting Professorships at the Dresden Max Planck Institute for Chemical Physics of Solids in 2005 and 2013. His research centers on the understanding of the chemical bond in transition metal inorganic chemistry. He uses a variety of quantum chemical computational tools to tackle problems of structural, electronic and physical properties of both molecular and solid state systems in the domain of inorganic chemistry. Outcomes of his research have resulted in ca. 250 books, chapters of books, papers and reviews published in international journals.