Organic Metals from Chiral BEDT-TTF Donors

Abstract

The chemistry and physics of solids with layered structures has been of central interest in the solid state sciences for several decades [1]. One of the many scientifically and technically important aspects connected with these materials is the possibility of pronounced two-dimensional delocalized interatomic and/or intermolecular electronic interactions, which lead to unusual magnetic and electric properties in the bulk. Especially remarkable are a variety of phase transitions, which occur in selected materials of this type at different temperatures. Typical, and very well-known, examples of such specimens are graphite, the binary sulfides MoS₂ and TaS₂, together with several of their intercalation compounds, ternary or quarternary chalcogenides and/or halides of the transition elements, and so on. Inorganic ternary systems, composed of anionic transition metal oxide layers and different kinds of countercations located between these anion sheets, are especially well-suited for systematic variations in composition and - as a consequence thereof - in solid state properties. Varying stages of band fillings can be achieved “chemically,” depending on the number of electrons per metal ion in the different sheets. The systematic work on these materials culminated in the discovery of superconductivity above 40 K by Müller and Bednorz in layered copper oxide structures [2].