Sulfidisch derivatisierte Oxodisilicate der schweren Lanthanide vom Formeltyp M4S3[Si2O7] (M = Gd - Tm) / Sulfide Derivatized Oxodisilicates of the Heavy Lanthanides with the Formula M4S3[Si2O7] (M = Gd - Tm)
2014
Sieke, Corinna | Hartenbach, Ingo | Schleid, Thomas
The sulfide derivatized oxodisilicates M₄S₃[Si₂O₇] of the heavy lanthanides (M = Gd - Tm) have been synthesized by reaction of M, M₂O₃, S, and SiO₂ using MCl₃ as flux in evacuated silica tubes at 850 °C for 7 d. The title compounds crystallize tetragonally in the space group I4₁/amd with 8 formula units per unit cell. Their crystal structure contains isolated [Si₂O₇]⁶⁻ pyroanions of two vertex-sharing [SiO₄] tetrahedra in eclipsed conformation with Si-O-Si bridging angles of about 130°. The two crystallographically independent lanthanide cations (M³⁺) both reside in tricapped trigonal prismatic environments of chalcogen ligands. In the case of M1 five S²⁻ and three plus one O²⁻ anions (CN = 8+1), for M2 three S²⁻ and six O²⁻ anions (CN = 9) fill the coordination spheres. Two of the three different sulfide anions are surrounded by four M³⁺ cations forming a seesaw (S2) and a square (S3), respectively. The third one (S1) is coordinated by six lanthanide cations in the form of a distorted octahedron. The whole structure is basically built up of cationic lanthanide silicate layers which are threaded by sulfide anions.
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