Two alternating BEDT-TTF packing motifs in alpha-kappa-(BEDT-TTF)(2)Hg (SCN)(3)

摘要

The first BEDT-TTF charge transfer salt in which alternating electron-donor layers possess alpha- and kappa-type packing motifs has been synthesized. The crystal structure and physical properties of the organic conductor alpha-kappa-(BEDT-TTF)(2)Hg(SCN)(3) are described, including a detailed description of its optical properties. The electronic behavior is dominated by a sharp metal-to-insulator transition at T = 176 K which is due to a first-order structural phase transition. The optical properties in the metallic regime are a superposition of those of the alpha- and kappa-phases, while in the insulating state the spectra become more anisotropic in the conducting plane, and the features of the two layers cannot be distinguished.