Flux Crystal Growth of Lanthanide Tungsten Oxychlorides, La8.64W6O30.45Cl, Ce8.64W5.74O30Cl, and Ln8.33W6O30Cl (Ln = Pr, Nd): Structural Stability in the Presence of Extreme Cation and Anion Disorder.

Abstract

A series of lanthanide tungsten oxychlorides with compositions of La8.64W6O30.45Cl, Ce8.64W5.74O30Cl, Pr8.33W6O30Cl, and Nd8.33W6O30Cl was synthesized as single crystals via a high-temperature flux growth method. The reduction of Ce(IV) to Ce(III) was performed in the synthesis of Ce8.64W5.74O30Cl using Zn metal as the reducing agent. All four compounds crystallize in the tetragonal space group P42/nmc with a highly disordered and rather unusual arrangement of Ln(III) and W(VI) cations. The three-dimensional crystal structure consists of a complex network of Ln cations occupying multiple coordination environments, including LnO8 cubes. The level of complexity the disorder adds to the overall structure was considered using calculations for the total information content of the crystal. The temperature dependence of the magnetic susceptibility of Pr8.33W6O30Cl and Nd8.33W6O30Cl was measured, and both compounds exhibit paramagnetic behavior across the entire 2-300 K temperature range measured.