The Crystal Structures of Er3OFS3 and Er3OF3S2: Two Erbium Oxide Fluoride Sulfides with Condensed Tetrahedral [ZEr4] Units (Z = O and F)

Sabine Strobel (1) , Alexander Müller (1) , Thomas Schleid (1)

1 Institut fuer Anorganische Chemie

The two new compounds Er3OFS3 and Er3OF3S2 vary mostly in their fluoride and sulfide content. The fluoride-poor erbium(III) oxide fluoride sulfide Er3OFS3 crystallizes in the tetragonal space group I4/mmm (a = 374.86(2), c = 2068.41(9) pm, Z = 2) with two crystallographically different Er3+ cations. (Er1)3+ is surrounded by six S2– anions in the shape of a slightly distorted octahedron, whereas (Er2)3+ exhibits a coordination number of eight (4 × O2–/F– and 4 × S2– arranged as a square antiprism). In the crystal structure of Er3OFS3 edge-sharing tetrahedral [ZEr4]10.5+ units (Zn– = 50% O2– + 50% F–) form condensed [OFEr2]3+ layers. These layers alternate with [ErS3]3– sheets, built up of [ErS6]9– octahedra, which are connected via four common edges, to complete the three-dimensional crystal structure of Er3OFS3. The fluoride-rich erbium(III) oxide fluoride sulfide Er3OF3S2 crystallizes in the orthorhombic space group Ccce (a = 538.31(2), b = 1892.03(9), c = 538.27(2) pm, Z = 4). Two crystallographically distinct Er3+ cations are present in its crystal structure. (Er1)3+ is surrounded by eight Zn– anions (Z = 25% O2– + 75% F–) in the shape of a twisted square antiprism, while (Er2)3+ holds a coordination number of nine (4 × O2–/F– and 5 × S2– arranged as a monocapped square antiprism), copying the coordination geometry of the Er3+ cations in PbFCl-type ErFS. The three-dimensional structure of Er3OF3S2 is built up of S2– sheets and [OF3Er3]4+ double layers, which are formed by strongly contorted tetrahedral [ZEr4]10.75+ units (Zn– = 25% O2– + 75% F–). The crystals of this compound show a prominent superstructure in the tetragonal space group I4/mmm with a = 380.59(3), c = 1892.03(9) pm and Z = 2. In the crystal structures of both title compounds, the light anions O2– and F– occupy one crystallographically unique Wyckoff position in a statistic allocation. Subject to the O/F content in the formulae, the ratio of O2– : F– is 1 : 1 in Er3OFS3 and 1 : 3 in Er3OF3S2.

Mots clés: Physical Sciences

Sabine Strobel, Alexander Müller, Thomas Schleid. The Crystal Structures of Er3OFS3 and Er3OF3S2: Two Erbium Oxide Fluoride Sulfides with Condensed Tetrahedral [ZEr4] Units (Z = O and F). Journal of Inorganic and General Chemistry / Zeitschrift für anorganische und allgemeine Chemie, 2009, 635 (12), pp.1940. ⟨10.1002/zaac.200900188⟩. ⟨hal-00507770⟩