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Pr 4 S 3 [AsS 3 ] 2 : Praseodymium(III) Sulfide Thioarsenate(III) with Chains and Layers of Condensed [SPr 4 ] Tetrahedra
Author(s) -
Kang DongHee,
Schleid Thomas
Publication year - 2009
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.200900225
Subject(s) - crystallography , chemistry , lone pair , trigonal crystal system , sulfur , monoclinic crystal system , crystal structure , stereochemistry , molecule , organic chemistry
Single crystals of Pr 4 S 3 [AsS 3 ] 2 can be obtained through the reaction between the elements praseodymium, arsenic and sulfur using CsCl as fluxing agent in torch‐sealed evacuated silica ampoules. The starting materials were heated for ten days at 700 °C and then cooled down slowly to room temperature. The transparent, pale greenish yellow platelets crystallize orthorhombically ( a = 2910.6(2), b = 699.74(5), c = 704.51(5) pm) in space group Pbcn (no. 60) with Z = 4. The new compound Pr 4 As 2 S 9 (≡ Pr 4 S 3 [AsS 3 ] 2 ) contains two crystallographically independent Pr 3+ cations. (Pr1) 3+ shows a bicapped trigonal prismatic environment of eight sulfur atoms (CN = 8), whereas (Pr2) 3+ is surrounded by only seven sulfur atoms in the shape of a monocapped trigonal prism (CN = 7). The isolated pyramidal thioarsenate(III) anions [AsS 3 ] 3– are formed as ψ 1 ‐tetrahedra by the three sulfur atoms ( d (As 3+ –S 2– ) = 223–228 pm, ∢(S–As–S) = 94–104°) and a non ‐binding electron pair ( lone pair ) at each As 3+ cation. Two of the five crystallographically different sulfur atoms (S1 and S2) are not connected to As 3+ at all, but coordinated by four Pr 3+ cations each to build up slightly distorted [SPr 4 ] 10+ tetrahedra ( d (S 2– –Pr 3+ ) = 281–289 pm, ∢(Pr–S–Pr) = 98–146°). Thus the crystal structure of Pr 4 S 3 [AsS 3 ] 2 exhibits endless {}^1_∞ {[(S1)Pr 4/2 ] 4+ } chains and {}^2_∞ {[(S2)Pr 4/4 ] + } layers, which consist of trans ‐edge condensed [(S1)Pr 4 ] 10+ tetrahedra for the chains and [(S2)Pr 4 ] 10+ tetrahedra sharing four common edges for layers. The lone pairs at the As 3+ cations close around the {}^1_∞ {[(S1)Pr 4/2 ] 4+ } chains running along [001]. The {}^2_∞ {[(S2)Pr 4/4 ] + } layers spread out parallel to the (100) plane and complete the crystal structure of Pr 4 S 3 [AsS 3 ] 2 according to {}^1_∞ {[(S1)(Pr1) 4/2 ] 4+ } {}^2_∞ {([(S2)(Pr2) 4/4 ] + ) 2 } {}^0_∞ {([As(S3)(S4)(S5)] 3– ) 2 }.