The First Quinary Rare Earth Thiophosphates: Cs₅Ln₃X₃(P₂S₆)₂(PS₄) (Ln = La, Ce, X = Br, Cl) and the Quasi-Quaternary Cs₁₀Y₄Cl₁₀(P₂S₆)₃

We report the first examples of quinary rare earth thiophosphates with a fully ordered cation and anion distribution, Cs₅Ln₃X₃(P₂S₆)₂(PS₄), (Ln = La, Ce and X = Br, Cl) as well as the quasi-quaternary Cs₁₀Y₄Cl₁₀(P₂S₆)₃. These four new compounds crystallize in three different, unknown structure types. The yellowish, transparent, brittle Cs₅Ce₃Br₃(P₂S₆)₂(PS₄) crystallizes in the orthorhombic space group Pnma (no. 62) with a = 13.276(3), b = 14.891(3), c = 19.593(4) Å, and V = 3873(1) ų in a novel structure type. Colorless crystals of Cs₅La₃Br₃(P₂S₆)₂(PS₄) and Cs₅La₃Cl₃(P₂S₆)₂(PS₄) are isotypic and were obtained in the monoclinic space group P2₁/m (no. 11) with a = 9.715(2), b = 14.310(3), c = 13.685(3) Å, β = 100.16(3)° and V = 1873(1) ų and a = 9.513(2), b = 14.182(3), c = 13.699(3) Å, β = 99.39(3)° and V = 1823(1) ų, respectively. Both structures contain isolated hexathiohypodiphosphate(IV) [P₂S₆]^4– and thiophosphate [PS₄]^3– units that are arranged alternately in layers. Cs₁₀Y₄Cl₁₀(P₂S₆)₃ crystallizes in colorless transparent platelets in the orthorhombic space group Pnnm (no. 58) with a = 13.153(3), b = 28.964(6), c = 7.780(2) Å, and V = 2964(1) ų. The structure is composed of isolated [P_4/2S₆]^4– octahedra containing four half occupied P positions surrounded octahedrally by sulfur. We show with Raman scattering that this disordered thiophosphate anion shows a Raman spectrum that is distinct from spectra published for other literature-known thiophosphate anions.