Structure and properties of TTP conductors substituted with ethylenedioxy group

ELSEVIER

Synthetic

Metals

102 (1999)

1720

Structure and properties of TlT conductors substituted with ethylenedioxy group K. Tanakaa, M. Taniguchia, Y. Misalciav*, T. Yamabea, T. Kawamotob, T. Morib a Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Yoshida, Kyoto 606-8501, Japan b Deparrment of Organic and Polymeric Materials, Tokyo Institute of Technology, 0-okayama, Tokyo 152-8552, Japan Abstract Radical cation salts of EOPT-TTP, where EOPT-+ITP is 2-(4,5-ethylenedioxy-1,3-dithiol-2-ylidene)-5-(4,5-propylenedi~io-1,3All the salts obtained so far exhibited metallic dithiol-2-ylidene)-1,3,4,6-tetrathiapentalene, have been prepared. dependence of resistivity down to low temperature regardless of shape and size of counter anions. keywords:

1.

Coupling

reaction,

Electrocrystallization,

Organic

conductors

Introduction

A bis-fused ‘ITF donor, 2,5-bis(l,3-dithiol-2-ylidene)1,3,4,6-tetrathiapentalene (TTP) and its derivatives are of interest because they have a strong tendency to yield highly conducting cation radical salts showing metallic conducting behaviour down to low temperatures [l]. In particular, ethylenedioxy substituted ‘ITP derivatives such as TMEO-Tl’P (4,5-bis(methylthio)-4’,5’-ethylenedioxy-TTP) forms many metallic radical cation salts stable down to s1.2 K [2]. In this connection, preparation of new ethylenedioxy substituted ‘ITPs is attractive in the search for novel organic metals. In these Proceedings we report conducting properties of radical cation salts based on EOPT-TIT’.

temperature

based on radical cation and/or anion salts.

dioxy-1,3-dithiole-2-thione (3) in refluxing toluene. Single crystals of its radical cation salts with C104-, BF4-, PF6‘, AsF6 and Au(CN)2- anions were grown by use of an electrocrystallization techni ue. These salts showed high conductivity of 101-lo2 S cm- P at room temperature [3]. It is noted that all of them exhibited metallic conducting behaviour down to liquid helium temperature regardless of shape and size of counter anions though resistivity of several salts increased a little at low tempera&es (Fig. 1):

1

EOPT-TTP

2.

Results

and

discussion

EOPT-TI’P was obtained in 24% yield by a trimetylphosphite-mediated cross coupling reaction between 1,3-dithiol-2one fused with 4,5-propylenedithio-‘ITF (2) and 4,5-ethylene-

0

100

200

300

Temperature I K Fig. 1. Conducting 3. [l] *Dr. Y. Misaki telephone; +81 75 753 5933, fax; +81 75 771 0172 e-mail: misakiBmee3.moleng.kyoto-u.ac.jp Acknowledgment: This work was partially supported by a Grant-in-Aid for Scientific Research (09640687). and by Japan Society for the Promotion of Science Research for the Future Program (JSPS-mF96pOO206). 0379-6779/99/$ - see front matter PII: SO379-6779(98)OOS93-5

0 1999

Elsevier

Science

S.A.

All rights

behaviour

of EOPT-‘ITP

salts.

References

T. Mori et al., Mol. Cryst. Liq. Cryst. 284 (1996) 271; Y. Misaki et al., Adv. Mater. 10 (1998) 588. [2] Y. Misaki et al., Chem. Lett. (1993) 2073; T. Mori et al., ibid. (1993) 2085. [3] Room temperature conductivity of EOPT-‘ITP salts are as follows: 79 (for the ClOq- salt), 78 (BF4-), 33 (PF6-), 5 (AsF6-) and 23 S cm-l (Au(CN)2-). reserved.