Salts of the tris(violurato)ferrate(II) ion: crystal structureof ammonium tris(violurato)ferrate(II) hydrate

Abstract

Salts of the type M⁺[FeV₃]^–·xH₂O have been prepared (where M⁺= alkali-metal cation, V^–= violurate) and found to be diamagnetic.

The crystal structure of the title compound [NH₄][FeV₃]·ca. 4.5H₂O has been determined by X-ray diffraction and refined by least squares to R 0.07 for 3 868 observed reflections. Crystals are triclinic, space group P, a= 16.242(3), b= 15.690(3), c= 9.848(2)Å, α= 90.95(2), β= 106.99(2), γ= 74.20(2)°, Z= 4. There are two independent cations and anions in the asymmetric unit; the geometry of the anion co-ordinated by three bidentate violurate ligands (V^–= C₄O₄N₃H₂^–) is fac(means: Fe–O 1.98₃, Fe–N 1.87₇Å), and closely resembles that found in ferroverdin. The accuracy of the structure is inhibited by serious disorder among the solvent molecules in the lattice.