THE NEW SALT KAPPA-ET(2)[HG(SCN)(2)I] - CRYSTAL-STRUCTURE AND PHYSICAL-PROPERTIES

The structure, resistivity and ESR of a new organic conductor kappa-ET (2)[Hg(SCN)(2)I] (ET = bis(ethylenedithio) tetrathiafulvalene) are stu died. Its main crystallographic parameters are found to be: M = 1213.2 , a = 38.03(1), b = 11.80(1), c = 8.329(9) Angstrom; gamma = 98.1(2)de grees; V = 3700(2) Angstrom(3); space group P2(1)/b; Z = 4. It is show n that the radical cations are packed according to the kappa-type in t he organic sheets, and the anions form polymerized chains. Two differe nt radical cation layers with different amounts of shortened S ... S c ontacts and distinct interaction between anionic and cationic sheets a re found. ESR linewidth is found to be 9-11 G (300 K), which is substa ntially narrower than a typical linewidth for ET-based radical cation salts of the K-type. Based on temperature dependences of the resistanc e anisotropy and ESR parameters, we suggest that a structure rearrange ment with electron localization may take place around 50 K. The compar ison of crystal structure and properties of the title compound with ot her salts of the family ET(2)[Hg(SCN)(3-n)X(n)], where X = Cl, Br, and n = 1, 2, is carried out.