Copper(I) coordination ability of the outer S-position isomer of EDT-DMT-TTF (D1): crystal structure of (D1)2Cu2Br4,2CH2Cl2; structural correlation with the (D1)2Cu2Br6 copper(II) salt

The (D1)2Cu2Br4,2CH2Cl2 (1) and (D1)2Cu2Br6 (2) radical cation salts, where D1 is the outer S-position isomer of ethylenedithiodimethylthiotetrathiafulvalene (EDT-DMT-TTF), have been synthesized and their X-ray crystal structures have been solved. The molecular structure of 1 is built up from (D1–Cu2Br4–D1) metal complexes. Each copper(I) atom is coordinated to a sulfur atom of the D1 disulfide bridge through a σ-type dative bond. Consequently, Cu2Br4 part is located between two organic molecules which are approximately plane and parallel to each other. In compound 2, (Cu2Br6)2− anions, in which copper atoms are at the +2 oxidation state, also lie between two oxidized donors. In both resulting structures, the D1–Cu2Brx–D1 parts (x=4 for 1, x=6 for 2) are stacking in order to form columns containing dimerized (D1+)2 units.