Radical Cation Salts of Cyanobenzene‐Ethylenedithio‐TTF Electron Donors with Halide (Cu and Hg) Binuclear Anions

Abstract

Three salts of the two isomers of the dissymmetric TTF‐derivative cyanobenzene‐ethylenedithio‐tetrathiafulvalene (CNB‐EDT‐TTF) with binuclear polyhalide complex dianions, namely [4‐CNB‐EDT‐TTF]2 [Cu2Cl6] (1); [5‐CNB‐EDT‐TTF]2 [Cu2Cl6] 2CH2Cl2 (2) and [5‐CNB‐EDT‐TTF]2 [Hg2Br6] (3) were prepared and characterized by single‐crystal X‐ray diffraction and magnetic susceptibility measurements. In spite of the different structural types of these compounds, the three compounds present donors in dimerized stacks. The crystal structures of 1 and 3 consist of segregated head‐to‐tail donor dimer stacks and dianion columns. The structural motif of 2 is mixed columns of alternating head‐to‐tail donor dimers and dianions. The three salts present C–N···H–C interactions, which in 2 and 3 can be described as a R22(10) synthon. The magnetic susceptibility of the salts with the paramagnetic (Cu2Cl6)2– dianion (1 and 2) show that they behave as paramagnets where the Cu2+ atoms of the dianion are antiferromagnetically coupled with magnetic exchange values J/kB of –58.8 and –155.6 K, respectively. The different J values are associated with differences in dianion geometry.