Structural and Physical Properties of New Conducting Cation Radical Salts with Te-Based Counteranions, Tetraiodotellurate(II) and Hexaiododitellurate(II)

Abstract

This article reports preparation, structure, and conducting property of several cation radical salts of organic donors tetramethyltetrathiafulvalene (TMTTF), ethylenedithiotetrathiafulvalene (EDT-TTF), bis(ethylenedithio)tetrathiafulvalene (ET), bis(ethylenedithio)tetraselenafulvalene (BETS) and hexamethylenetetraselenafulvalene (HMTSF) with two novel planar Te-based dianions, TeI 4 2− and Te 2I 6 2−. (ET) 5Te 2I 6 1 and (BETS) 5Te 2I 6 2 are isostructural. In these Te 2I 6 2− salts, intermolecular short I···I contacts form a supramolecular corrugated anion sheet. Donor arrangement is similar to the θ-type. With lowering temperature, the resistivity of 1 shows a gradual increase followed by a sharp upturn at 110 K. 2 is metallic down to 120 K and shows a gradual increase of the resistivity followed by a clear transition to an insulating state around 60 K. Crystal structure of (ET) 4TeI 4 3 is based on the “herring bone” arrangement of ET molecules similar to the α-type. 3 shows a semiconductive behavior around room temperature followed by a transition to an insulating state at 210 K. (EDT-TTF) 4TeI 4 4, a semiconductor, exhibits a unique two-dimensional arrangement of dimerized EDT-TTF molecules.