Abstract

(ET)₃Cl(pBIB) (ET = bis(ethylenedithio)tetrathiafulvalene, pBIB = p-bis(iodoethynyl)benzene) salt is a unique organic metal containing supramolecular assemblies based on the pBIB molecule and the Cl anion. We newly prepared chloride and bromide ET cation radical salts with the use of di- and tetra-substituted pBIB derivatives: 1,4-difluoro-2,5-bis(iodoethynyl)benzene (DFBIB), 1,2,4,5-tetrafluoro-3,6-bis(iodoethynyl)benzene (TFBIB), 1,4-bis(iodoethynyl)-2,5-dimethylbenzene (BIDMB), and p-bis(iodoethynyl)benzene-d₄ (pBIB-d₄). The effect of substitution has been studied by X-ray structure analyses, tight-binding band calculations, and resistivity measurements. Halide ion replacement as well as deuterium- and difluoro-substitutions do not change the fundamental crystal structure and the metallic behavior, but affect the anisotropy of the electronic structure. On the other hand, the tetrafluoro- and dimethyl-substitutions induce different donor arrangements that lead to semiconducting behaviors.