Electrical Properties and Structure of the Organic Metallic Compound bis (tetraselenotetracene)‐iodide, (TSeT)₂‐I

Abstract

Abstract The preparation of the new organic metallic compound (TSeT) 2 ‐I is reported. The crystal structure of the free donor, TSeT, is discussed and compared with the crystal structure of (TSeT) 2 ‐I. The latter has the orthorhombic space group P 2 1 2 1 2 and hence is not isomorphous with the analogous compounds (TSeT) 2 ‐Cl and (TSeT) 2 ‐Br, described by Shchegolev et al. [4]. In contrast to those complexes (TSeT) 2 ‐I consists of only one set of crystallographically equivalent chains and therefore its transition to the low‐temperature conducting state ( Fig. 6 ) is also of different type. The d. c. resistivity at 300 K ranges from 10 −3 to 1.5 ·. 10 −4 Ω cm. The temperature dependence of the d.c. resistivity of the title compound is given: in the temperature range from 300 to 80 K the normalized d.c. resistivity is described by ρ(T)/ρ(300) ∝ T 1.7 . Between 80 and 70 K a slight deviation from the above law has been detected which is taken as an indication of a phase transition; its nature is, however, not yet definable. The low‐temperature conducting state reached at about 70 K shows an almost constant resistivity in the interval 60 K to 45 K. Its normalized d.c. resistivity in the range 4.5 K‐50 K is described by ρ(T)/ρ(300) ∝ (T−T m ) 3 , with T m = 50 K. The value of the normalized resistivity extrapolated to O K is 0.75.