Synthesis, conductivity, and the crystal structure of a new stable metal, β″-(DOEO)₂HSeO₄ · H₂O

Abstract

The stable metal β″-(DOEO)₂HSeO₄ · H₂O I) based on a new donor compound, 3,4-(1,4-dioxanediyl-2,3-dithio)-3′,4′-ethylenedioxo-2,5,2′,5′-tetrathiafulvalene] (DOEO), is synthesized and structurally characterized for the first time. The synthesis is performed by the electrocrystallization technique (direct current density j = 2 × 10⁻⁶ A/cm²). The crystals are triclinic, and the unit cell parameters are as follows: a = 5.495(1) Å, b = 9.715(2) Å, c = 16.878(3) Å, α = 83.52(3)°, β = 82.54(3)°, γ = 73.51(3)°, Z = 1, and space group $P\bar 1$. The salt has a layered structure. The DOEO ^1/2+ radical cation layers are aligned parallel to the ab planes. The HS_eO ⁻₄ · H₂O solvated anions are located in channels along the a axis and are disordered over two positions near the center of symmetry (1/2 0 0) with a probability of 50%. The conductivity of the salt is equal to 300–400 Ω⁻¹ cm⁻¹ at room temperature and increases upon cooling to the boiling point of liquid helium (4.2 K) by a factor of 100–200 depending on the sample.