Twinned single crystal structure of Li4P2S6.

Yellow needles-like single crystals of Li₄P₂S₆ were obtained serendipitously during the preparation of Li₇P₃S₁₀O. The twinned crystal structure of Li₄P₂S₆ was determined from single-crystal X-ray diffraction data [wR(F²) = 0.069, 716 reflections, 40 variables]. Li₄P₂S₆ crystallizes in the trigonal system, space group P 3 ‾ m 1 (N° 164), a = 10.5042(8) Å, c = 6.5837(6) Å, V = 629.11(9) ų and Z = 2. The lithium octahedra form a [Li₄S₆]⁸⁻ honeycomb-like structure within which diphosphate units are located. The comparison of our crystal structure to those of P6₃/mcm-, P 3 ‾ 1 m -, and P321-Li₄P₂S₆ demonstrated group-subgroup relationships and associated the disorder or order of the phosphorus atoms within the identical [Li₄S₆]⁸⁻ 3d-frameworks to the choice of the unit cell (the subcell with a ∼ 6.07 Å vs. the supercell with a ∼ 10.5 Å). [ABSTRACT FROM AUTHOR]