Prism Inside: Spectroscopic and Magnetic Properties of the Lanthanide(III) Chloride Oxidotungstates(VI) Ln3Cl3[WO6] (Ln = La - Nd, Sm - Tb)

The lanthanide(III) chloride oxidotungstates(VI) with the formula Ln(3)Cl(3)[WO6] for Ln = La - Nd, Sm - Tb were synthesized by solid-state reactions utilizing the respective lanthanide trichloride, lanthanide sesquioxide (where available), and tungsten trioxide together with lithium chloride as flux. The title compounds crystallize hexagonally in space group P6(3)/m (no. 176, a = 941-909, c = 543-525 pm, Z = 2). The structures comprise crystallographically unique Ln(3+) cations surrounded by six O2- and four Cl- anions (C.N. = 10) forming distorted tetracapped trigonal prisms as well as rather uncommon trigonal prismatic [WO6](6-) units, whose edges are coordinated by nine Ln(3+) cations. Thus, a (3)(infinity){([WO6]Ln(9/3)(e))(3+)} framework (e = edge-sharing) is created, which contains tube-shaped channels along [001] lined with chloride anions. To elucidate the spectroscopic and magnetic properties of the obtained pure phase samples, single-crystal Raman (for Ln = La - Nd, Sm-Tb), diffuse reflectance (for Ln = La, Pr, Nd, Gd), and luminescence spectroscopy (for bulk Ln(3)Cl(3)[WO6] (Ln = La, Eu, Gd, Tb) and Eu3+- or Tb3+-doped derivatives of La3Cl3[WO6] and Gd3Cl3[WO6], respectively) were performed and their temperature-dependent magnetic moments (for Ln = Pr, Nd, Gd) were determined.