Structures and Properties of New Organic Conductors: BEDT-TTF, BEST and BETS Salts of the HOC2H4SO3− Anion

Hiroki Akutsu,Yuta Koyama,Keigo Furuta,Yasuhiro Nakazawa,Scott S Turner

doi:10.3390/cryst10090775

Hiroki Akutsu, Yuta Koyama + Show 3 more

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https://doi.org/10.3390/cryst10090775

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Abstract

New bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF)-, bis(ethylenediseleno)tetrathiafulvalene (BEST)- and bis(ethylenedithio)tetraselenafulvalene (BETS)-based organic charge-transfer (CT) salts—α-(BEDT-TTF)3(HOC2H4SO3)2 (1), β-(BEST)3(HOC2H4SO3)2·H2O (2) and α-(BETS)2(HOC2H4SO3)·H2O (3)—have been prepared. Salts 1 and 2 show semiconducting behaviour. Salt 3, which is almost isostructural to α-(BETS)2I3, shows metallic behaviour down to 70 K and then shows a broader metal–insulator transition than that of α-(BETS)2I3. The reason for the difference in behaviour is estimated by the comparison of the Madelung energies of the full set of patterns of possible donor’s charge-ordered and anion’s disordered states.

Highlights

Organic conductors have been synthesized by chemists [1,2] and their physical properties have been measured by physicists [3,4] for some time
The mechanism it is believed that both MI transition mechanisms are similar
The HOC2 H4 SO3 − anion in 3 is disordered, the randomness of which appears to make the resistivity behaviour vary as a function of the measured sample, which is supported by Madelung energy calculations

Summary

Introduction

Organic conductors have been synthesized by chemists [1,2] and their physical properties have been measured by physicists [3,4] for some time now. Popular salts are κ-(BEDT-TTF) Cu(NCS)2 [6], where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene; κ-(BEDT-TTF) Cu[N(CN)2 ]X (X = Cl, Br) [7,8]; θ-(BEDT-TTF)2 [MM0 (SCN)4 ] (M = Cs, Rb, Tl; M0 = Zn, Co) [9]; α-(BEDT-TTF)2 [AHg(SCN)4 ] (A = K, NH4 ) [10,11]; α-(D) I3 (D = BEDT-TTF [12]; BETS [13], where BETS = bis(ethylenedithio)tetraselenafulvalene); and (TMTSF) X (X = PF6 , AsF6 , ClO4 , etc., where TMTSF = tetramethyltetrathiafulvalene) [14] Most of these examples were first made for more than a quarter of a century ago. This may be because organic conductors prepared recently have had more complicated molecular and/or crystal structures, which are definitely interesting for chemists

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Discussion

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