Syntheses and crystal structures of the rare-earth metal(III) bromide ortho-oxidotungstates(VI) with the formula REBr[WO4] (RE = Y, Gd–Yb)

• The REBr[WO4] series for RE = Y, Gd–Yb was synthesized as pure phase materials.
• The structure of every representative was determined via single-crystal X-ray data.
• Previously reported structures were corrected.
• Magnetic measurements of HoBr[WO4] showed no long range ordering.

The rare-earth metal(III) bromide ortho-oxidotungstates(VI) with the formula REBr[WO4] crystallize triclinically in space group P  1¯ (a = 689–693, b = 715–728, c = 1074–1107 pm, α = 103–106, β ≈ 108 and γ = 93–95°, Z = 4) for RE = Y, Gd–Yb. Their crystal structure is isotypic with the most examples of the formally analogous lanthanoid(III) bromide oxidomolybdates(VI) REBr[MoO4] with RE = Y, Pr, Nd, Sm, Gd–Lu. It contains two crystallographically different rare-earth metal(III) cations with coordination numbers of seven plus one for (RE1)3+ and seven for (RE2)3+. The (RE1)3+ cations are surrounded by three Br– and four plus one O2− anions forming distorted trigonal dodecahedra, while the (RE2)3+ cations exhibit a coordination environment of one Br– and six O2− anions in the shape of a monocapped trigonal prism. Furthermore, the structure contains two crystallographically independent, isolated tetrahedral [WO4]2− units. All these polyhedra are fused together to form 1∞{REBr[WO4]} chains running along [012]. Since the title compounds, synthesized by solid-state reactions from the underlying binaries, emerge as pure phases according to X-ray powder diffractometry, spectroscopic and magnetic measurements were performed.

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