Die Kristallstrukturen von (NEt₄ ⁺)₂[Se₅ ^2- · 1/2 Se₆·Se₇] und von (NPr₄)₂Se₁₁ / The Crystal Structures of (NEt₄ ⁺)₂[Se₅ ^2- · 1/2 Se₆ · Se₇] and (NPr₄)₂Se₁₁

Abstract

The title compounds have been prepared by the reactions of a potassium diselenide solution in DMF with excess selenium in the presence of tetraethyl and tetrapropyl ammonium chloride, respectively. They were characterized by X-ray crystal structure determinations. (NEt 4 + ) 2 [Se 5 2- ·1 /2 Se 6 · Se 7 ]: Space group PĪ, Z = 2, 2514 observed unique reflections, R = 0.085. Lattice dimensions at —40 °C: a = 957.7(4), b = 1384.2(4), c = 1545.3(7) pm, α = 107.32(3)°, β = 97.27(4)°, γ = 105.94(3)°. The compound has an ionic structure of NEt 4 + ions and chains of pentaselenide ions, which are associated with Se 6 and Se 7 , ring molecules, forming layers parallel to (110). (NPr 4 ) 2 Se 11 : Space group C2/c, Ζ = 4, 2198 observed unique reflections, R = 0.082. Lattice dimensions at —40 °C: a = 2364.7(5), b = 1206.8(2), c = 1609.6(3) pm, β = 118.74(3)°. The compound consists of cations (N(C 3 H 7 ) 4 + and spirocyclic anions Se 11 2- , in which two Se 6 rings having chair conformation are linked by a common Se atom with planar coordination. There are no short contacts between the S 11 2- ions.