Crystal Structure and Vibrational Spectrum of Thallium(I) Europium(II) Tetrathiophosphate(V), TIEu[PS 4 ]

TlEu[PS 4 ] was synthesized from the elements in a sealed quartz ampoule at 1 150 K. The compound forms transparent orange needles, stable in air and moisture. It crystallizes in the orthorhombic system, space group Pnma (No. 62), with cell dimensions a = 12.157(2), b = 6.581(1), c = 8.802(2) Å, Z = 4. The crystal structure consists of discrete [PS 4 ] 3− anions interconnected by Tl + and Eu 2+ . The tetrahedral [PS 4 ] 3− groups are slightly distorted with PS bond lengths in the range 2.028 to 2.043 Å. These tetrahedral anions are arranged in such a way that the sulfur atoms form columns of distorted trigonal S 6 prisms along [0 0 1]. The columns are condensed via common edges to puckered layers parallel to (1 0 0). The interlayer region consists of empty distorted half‐cubes and tetrahedral holes, half of them filled by P atoms. The trigonal prisms in the columns are centered alternately by Tl + and Eu 2+ . In this way, the structure can be regarded as an ordered superstructure of the InNi 2 type, where half of the tetrahedral holes are filled by phosphorus atoms: InInNi 4 □   2 tet≙ TlEuS 4 P□   1 tet . TlEu[PS 4 ] is a centrosymmetric variant of the TlSn[PS 4 ] structure type (space group Pna 2 1 ). The vibrational spectrum is in accordance with the X‐ray crystal structure, the Raman and infrared vibrations are assigned on the basis of [PS 4 ] 3− units with C 2v symmetry.