S· · ·S Contact-assembled tetrathiafulvalene derivatives of copper(I) and silver(I) co-ordination polymers and organic radical cation salt

Abstract

The reactions of 2-[4,5-bis(methylsulfanyl)-1,3-dithiol-2-ylidene]-4,5-bis(2-cyanoethylsulfanyl)-1,3-dithiole (CM-TTF) with copper(II) and silver(I) salts resulted in the isolation and structural characterization of S· · ·S contact assembled co-ordination polymers, [Cu(CM-TTF)][ClO₄]·thf 1 and [Ag(CM-TTF)(CF₃SO₃)] 2, and radical cation salt, [CM-TTF][CuCl₂] 3. Both 1 and 2 are 1∶1 metal–ligand complexes in which the metal ions and CM-TTF molecules are alternately linked forming two-dimensional networks and infinite linear chain structures, respectively, which are further reinforced by close intermolecular S· · ·S interactions. The structure of 3 consists of segregated stacks of CM-TTF^˙+ donors and CuCl₂^– acceptors associated via short S· · ·Cl contacts leading to an alternate donor–acceptor–donor columnar arrangement. The complexes were additionally characterized by IR, UV/VIS and ESR spectra as well as electrical resistivity measurements. All the complexes and their corresponding air-oxidized species are poor electrical conductors, but they show typical charge-transfer ESR signals and electronic absorptions. Complex 3 was found to exhibit transition from antiferro- to ferro-magnetic coupling upon air oxidation.