Radical Cation Salts Of Cyanobenzene-Ethylenedithio-Ttf Electron Donors With Halide (Cu And Hg) Binuclear Anions

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] 2CH(2)Cl(2) (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 center dot center dot center dot H-C interactions, which in 2 and 3 can be described as a R-2(2)(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/k(B) of -58.8 and -155.6 K, respectively. The different J values are associated with differences in dianion geometry.