Synthesis and Properties of 2-Alkylidene-1,3-dithiolo[4,5-d]-4,5-ethylenediselenotetrathiafulvalene Derivatives and Crystal Structures of Their Cation Radical Salts

Abstract

) at room temperature and the band calculation suggests that they are band insulator.

Molecular Conductors with Effectively Half‐Filled Electronic States Based on Tetrathiafulvalene Derivatives Condensed with a 2‐Isopropylidene‐1,3‐dithiole Ring

“…A 1,3‐dithiole ring substituted with an ethylenediseleno group bends with a folding angle of 22.3(3)° and the ethylenediseleno group adopts a sofa conformation 9. These findings are consistent with the optimized structure based on DFT calculations (17.0°) 8. By contrast, the folding angles of 1,3‐dithiole rings in the tetrathiapentalene unit are 7.1(3) and 7.6(6)°.…”

“…The room‐temperature conductivity ( σ rt ) of the black rodlike crystals of the Ag(CN) 2 salt is 0.12 S cm –1 , and this salt shows semiconducting behavior with an activation energy of 0.13 eV. The conducting property of the black rodlike crystals of the Ag(CN) 2 salt resembles 1:1 salts of 3 ( σ rt = 0.0044–0.053 S cm –1 ; E a = 0.058–0.15 eV) reported in our previous work 8. However, the σ rt values of the dark red plates of the Ag(CN) 2 and Au(CN) 2 salts are 4.2 and 78 S cm –1 , respectively.…”

“…The electron donor 3 was synthesized according to the literature 8. Single crystals of 3 were obtained by slow evaporation of the solution of 3 in CS 2 /EtOH.…”

“…We have already reported on the crystal structure of the salt with a large I 3 anion (9.8 Å). Its donor–anion ratio is 1:1, and the donor molecules do not construct a columnar structure 8. However, the length of M(CN) 2 anions (M = Ag and Au) is 9.4 Å.…”

“…The reduction of the effective bandwidth ( W eff ) is accomplished in this system; the stable metallic nature, however, is retained due to the effective 2/3‐filled band derived from the 3:1 composition. Since the degree of dimerization is often enhanced by the introduction of the steric hindrance, we have previously synthesized 2‐isopropylidene‐1,3‐dithiolo[4,5‐ d ]‐4,5‐ethylenediseleno‐TTF ( 3 ), in which the bulky and nonplanar ethylenediseleno group is introduced as the steric hindrance 8. Crystal‐structure analysis of the salts with 3 demonstrated that the donor molecules often form a head‐to‐tail dimer.…”