Strukturelle und magnetische Untersuchungen an Hexachlorowolframaten(V)

Structural and Magnetic Investigations of Hexachlorotungstates(V) CsWCl₆ crystallizes in the monoclinic space group C2/c with the lattice dimensions a = 12.097(8), b = 6.327(5), c = 15.30(1) Å, β = 128.4(1)° and 4 formula units. The compounds AWCl₆ (A = Rb, K, NH₄) are isotypic with CsWCl₆ as shown by powder patterns. Single-crystal photographs of [N(C₂H₅)₄]WCl₆ show monoclinic symmetry, space group P2₁/n with a = 11.737(8), b = 10.239(7), c = 7.191(5), β = 101.46(8)° and Z = 2. Both structures are composed of scarcely deformed WCl₆ octahedra. The trigonal compression of the octahedra results in a slightly negative deformation parameter according to the Figgis-model of the magnetic behaviour of d¹-systems. Above 80 K the μ² vs. T-curve is linear. This leads to a spin-orbit coupling constant of 1250 ± 200 cm^?1 and a covalence parameter of 0.6–0.8. Comparing the spectra of WCl₆, CsWCl₆ and Cs₂WCl₆ the beginning of the charge-transfer region was determined. The crystal field strength for CsWCl₆ was found as Δ = 16 000 cm^?1.