Molecular Conductors Based on peri‐Ditellurium‐Bridged Donors,2,3‐DMTTeA and TMTTeN

Abstract

AbstractMolecular conductors based on peri‐ditellurium‐bridged polyacene donor molecules 3,4‐dimethylanthra[1,9‐cd:4,10‐c'd']bis[1,2]ditellurole (2,3‐DMTTeA) and 2,3,6,7‐tetramethylnaphtho[1,8‐cd:4,5‐c'd']bis[1,2]ditellurole (TMTTeN) were prepared. The crystal structure analyses of neutral 2,3‐DMTTeA molecule and its cation radical salts revealed that these crystals involve an orientational disorder of the asymmetrical molecule, 2,3‐DMTTeA, and that the intermolecular network through tellurium atoms is very strong and dominant in terms of the construction of the crystal frameworks. In the crystal of (TMTTeN)2M(CN)2 (M = Ag and Au), the crystal structure analyses and the extended Hückel tight‐binding band calculations indicated that these salts are quasi three‐dimensional conductors. These salts are highly conductive (720–760 S cm–1) and maintain metallic states down to about 50 K. Furthermore, the Ag(CN)2– salt exhibited a Pauli paramagnetic behavior down to 2 K [χ(para) ≈ 2.0–2.5 × 10–4 emu mol–1]. In the crystal of (TMTTeN)(SCN)0.88, the donor molecules are stacked to form one‐dimensional columns and construct a three‐dimensional network between the columns through the intermolecular Te···Te contacts. The SCN– salt is also highly conductive (590 S cm–1) and maintains a metallic behavior down to 4.2 K. Almost temperature‐independent paramagnetic susceptibility of (TMTTeN)(SCN)0.88 indicates Pauli paramagnetism of this salt[χ(para) ≈ 1.6–1.9 × 10–4 emu mol–1]. A tight‐binding band structure calculation indicates that the Fermi surface of the SCN– salt is open along the b* and c* directions, but the intermolecular interactions between the donor columns are not so weak because of the three‐dimensional networkmediated by the protruded tellurium atoms. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)