Synthesis and Crystal Structure of SnP₂S₆

We report the synthesis and single-crystal analysis of the first layered AP₂S₆ compound. The structure of the title compound, SnP₂S₆, is rhombohedral, space group R₃ with a = 5.999(2) Å and c = 19.424(4) Å and Z = 3. The diffraction data are refined to a final R value of 0.0158. This compound is an ordered defect structure of the Fe₂P₂S₆ type where one-half of the metal sites are vacant. Hence, the tin atoms in SnP₂S₆ have a formal oxidation state of +4. This compound has previously been shown by us to display nonlinear optical behavior.