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Thiosilicate der Selten‐Erd‐Elemente: IV. Die quasi ‐isostrukturellen Verbindungen NaSm 3 S 3 [SiS 4 ], CuCe 3 S 3 [SiS 4 ], Ag 0,63 Ce 3 S 2,63 Cl 0,37 [SiS 4 ] und Sm 3 S 2 Cl[SiS 4 ] – Synthese, Kristallstruktur und Untersuchungen zur Silberionendynamik

2007; Wiley; Volume: 633; Issue: 13-14 Linguagem: Inglês

10.1002/zaac.200700356

1521-3749

Ingo Hartenbach, Tom Nilges, Thomas Schleid,

Organometallic Compounds Synthesis and Characterization

Abstract Thiosilicates of the Rare‐Earth Elements: IV. The quasi ‐isostructural Compounds NaSm 3 S 3 [SiS 4 ], CuCe 3 S 3 [SiS 4 ], Ag 0,63 Ce 3 S 2,63 Cl 0,37 [SiS 4 ] and Sm 3 S 2 Cl[SiS 4 ] – Synthesis, Crystal Structure and Investigations of the Silver‐Cation Motion The four lanthanoid(III) thiosilicates NaSm 3 S 3 [SiS 4 ] ( 1 ), CuCe 3 S 3 [SiS 4 ] ( 2 ), Ag 0,63 Ce 3 S 2,63 Cl 0,37 [SiS 4 ] ( 3 ) and Sm 3 S 2 Cl[SiS 4 ] ( 4 ) crystallize all hexagonally in the non ‐centrosymmetric space group P 6 3 (no. 173) showing basically the same structure. Besides an eightfold square‐antiprismatic sulfide coordination sphere about the M 3+ cations these compounds display discrete tetrahedral thiosilicate units [SiS 4 ] 4− which are trigonally distorted. All tops of the remaining pyramids point into the same direction along the c axis and therefore the structure needs to be non ‐centrosymmetric. However, the main feature of these crystals are channels along [001], built up by non ‐silicon bonded sulfide anions and providing trigonal planar (CN = 3) and trigonal antiprismatic (CN = 6) voids. In the sodium derivative ( 1 ) the Na + cations reside almost in the center of the latter ones exhibiting a trigonally distorted octahedral surrounding (CN = 6) while the Cu + cations of the respective thiosilicate ( 2 ) are situated in the middle of an (S 2− ) 3 triangle (CN = 3), just 7 pm above its plane. The same is true for the silver compound ( 3 ) with the exception of the Ag + cations sitting about 53 pm above the sulfide triangle and showing a marked under ‐occupation along with a very large U 33 displacement parameter. These facts lead to the assumption that ( 3 ) could be a promising material for ionic Ag + conduction. In order to maintain electroneutrality the silver derivative has to contain a certain amount of Cl − anions (CeCl 3 was used as fluxing agent) substituting S 2− which was doubtlessly confirmed by WDX analyses. In the absence of any monovalent cation (A + ) the analogous structure is realized in ( 4 ) displaying an empty channel along [001] and a complete substitution of one sulfide by one chloride anion per formula unit, also confirmed by electron‐beam microanalysis.