http://projects.itn.pt/HeterNetworks_SRabaca/Coordination_Chemistry_Reviews_227_2002_93_127.pdf

Metal bis-1,2-dithiolene complexes in conducting or magnetic crystalline assemblies

Since the first report of superconductivity in synthetic organic conductors in 1980, chemistry and physics of molecular-based conductors have achieved remarkable progress and a number of exotic phenomena have been reported. From the viewpoint of the electronic structure, this progress has been driven along the following two major trends: (1) from “onedimensional” to “higher dimensional” and (2) from “single-component” to “multicomponent”.1 Since planar π-conjugated molecules tend to stack to form the column structure, molecular metals developed in the early stage had the one-dimensional (1D) electronic structure. The 1D metallic electron system characterized by a pair of planar Fermi surface is inherently unstable and undergoes a metal-insulator transition accompanied by the density wave formation at low temperatures.2 Much effort to increase the dimensionality of the electronic structure has been made by means of chemical modification and/or application of pressure. The first organic superconducting system, (TMTSF)2X (TMTSF ) tetramethyltetraselenafulvalene), forms a quasi1D system.3 The organic donor BEDT-TTF (ET, bis(ethylenedithio)tetrathiafulvalene) has provided various types of two-dimensional (2D) metallic systems.4 And, the DCNQI-Cu (DCNQI ) N,N′-dicyanoquinonediimine) salt is the first molecular conductor where the existence of a three-dimensional (3D) Fermi surface is confirmed.5 On the other hand, for many years, molecular conductors were assumed to be electronically single-component systems which exhibit only one electron type. Although the first organic metal TTF-TCNQ (TTF ) tetrathiafulvalene; TCNQ ) tetracyanoquinodimethane) is well-known to consist of two conducting components, the electronic structure of this system has an only 1D pπ electron character.1 Over the past decade, however, an increasing number of multicomponent systems, where there exist “two” energy bands with different characters (for example, orbital character and dimensionality) near the Fermi level or where a strong interaction between itinerant pπ electrons and localized d electron spins operates, have been reported. Reizo Kato was born in 1955 in Yamaguchi, Japan. He received his B.Sc. in 1979, M.Sc. in 1981, and D.Sc. in 1984 from the University of Tokyo. He was appointed research associate of Department of Chemistry at Toho University in 1984, and he was promoted to lecturer in 1988. He joined the Institute for Solid State Physics in The University of Tokyo as an associate professor in 1990. Since 1999 he has been a chief scientist and a director of the Condensed Molecular Materials laboratory in RIKEN (The Institute of Physical and Chemical Research). He received the Chemical Society of Japan Award for Young Chemists in 1990 and the IBM Japan Science Prize in 1995 for his works on molecular conductors. His research has been focused on development of new molecular materials, especially molecular metals and superconductors. 5319 Chem. Rev. 2004, 104, 5319−5346

Conducting metal dithiolene complexes: structural and electronic properties.

We introduce the development of conductive organic molecular assemblies including organic metals, superconductors, single component conductors, conductive films, and conductive liquids, particularl...

Development of Conductive Organic Molecular Assemblies: Organic Metals, Superconductors, and Exotic Functional Materials

Toward systematic understanding of diversity of electronic properties in low-dimensional molecular solids.

We review the interplay of frustration and strong electronic correlations in quasi-two-dimensional organic charge transfer salts, such as (BEDT-TTF)2X and EtnMe4−nPn[Pd(dmit)2]2. These two forces drive a range of exotic phases including spin liquids, valence bond crystals, pseudogapped metals and unconventional superconductivity. Of particular interest is that in several materials pressure drives a first-order transition from a spin liquid Mott insulating state to a superconducting state. Experiments on these materials raise a number of profound questions about the quantum behaviour of frustrated systems, particularly the intimate connection between spin liquids and superconductivity. Insights into these questions have come from a wide range of theoretical techniques including first principles electronic structure, quantum many-body theory and quantum field theory. In this review we introduce some of the basic ideas of the field by discussing a simple frustrated Heisenberg model with four spins. We then describe the key experimental results, emphasizing that for two materials, κ-(BEDT-TTF)2Cu2(CN)3 and EtMe3Sb[Pd(dmit)2]2, there is strong evidence for a spin liquid ground state, and for another, EtMe3P[Pd(dmit)2]2, there is evidence of a valence bond crystal ground state. We review theoretical attempts to explain these phenomena, arguing that they can be captured by a Hubbard model on the anisotropic triangular lattice at half filling, and that resonating valence bond wavefunctions capture most of the essential physics. We review evidence that this Hubbard model can have a spin liquid ground state for a range of parameters that are realistic for the relevant materials. In particular, spatial anisotropy and ring exchange are key to destabilizing magnetic order. We conclude by summarizing the progress made thus far and identifying some of the key questions still to be answered.

https://iopscience.iop.org/article/10.1088/0034-4885/74/5/056501/pdf

Quantum frustration in organic Mott insulators: from spin liquids to unconventional superconductors

A new molecular superconductor β′-Et2Me2P[Pd(dmit)2]2 (dmit = 2-thioxo-1,3-dithiole-4,5-dithiolate)

New “unsymmetrical” (mixed ligand) metal dithiolate complexes, expected as components of molecular conductors, have been obtained by a ligand-exchange reaction in refluxing acetone, followed by iso...

Yoshiaki Kashimura

Papers

A new molecular superconductor β′-Et2Me2P[Pd(dmit)2]2 (dmit = 2-thioxo-1,3-dithiole-4,5-dithiolate)

Synthesis, Structure, and Electrochemical Properties of New “Unsymmetrical” Metal Dithiolate Complexes

Anomalous pressure-temperature phase diagram of the molecular conductor, (DI-DCNQI)2Cu (DI-DCNQI=2,5-DIIODO-N,N′-dicyanoquinonediimine)

Enhanced magnetic susceptibility of (DI-DCNQI)2Cu

Synthesis, structures, and physical properties of molecular conductors based on unsymmetrical metal-dithiolene complexes