Neutral Metal 1,2-Dithiolenes: Preparations, Properties and Possible Applications of Unsymmetrical in Comparison to the Symmetrical

Abstract

This paper is an overview concerning the preparations and properties as well as possible applications of neutral (one component) metal 1,2-dithiolenes (and selenium analogues). The structural, chemical, electrochemical, optical and electrical behavior of these complexes depend strongly on the nature of ligand and/or the metal. The results of unsymmetrical in comparison to those of symmetrical complexes related to the properties of materials in the solid state are primarily discussed. The optical absorption spectra exhibit strong bands in the near IR spectral region ca. 700 to ca. 1950 nm. X-ray crystal structure solutions show that the complexes usually have square-planar geometry with S–S and/or M–S contacts. Some of them behave as semiconductors or conductors (metals) and are stable in air. The cyclic voltammograms at negative potentials are different from the corresponding potentials of tetrathiafulvalenes (TTFs). As a consequence, the LUMO bands occur at much lower levels than those of TTFs. Consequently, electrical measurements under conditions of field effect transistors exhibit n-type or ambipolar behavior. Illumination of materials with high power lasers exhibits non-linear optical behavior. These properties enable metal 1,2-dithiolene complexes to be classified as promising candidates for optical and electronic applications, (e.g., saturable absorbers, ambipolar inverters).

Keywords

• neutral metal 1,2-dithiolenes
• semiconductors
• field effect transistors
• optical properties
• nonlinear optical properties