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Methanolothermale Synthese von Rb 3 AsSe 4 · 2Se 6 und Cs 3 AsSe 4 · 2Cs 2 As 2 Se 4 · 6Te 4 Se 2 , zwei Selenidoarsenate mit sechsgliedrigen Chalkogenringen/ Methanolothermal Synthesis of Rb 3 AsSe 4 · 2Se 6 and Cs 3 AsSe 4 · 2Cs 2 As 2 Se 4 · 6Te 4 Se 2 . Two Selenidoarsenates with Six-Membered Chalcogen …

1997; De Gruyter; Volume: 52; Issue: 2 Linguagem: Inglês

10.1515/znb-1997-0204

1865-7117

Michael Wachhold, William S. Sheldrick,

Solid-state spectroscopy and crystallography

Abstract The methanolothermal reaction of Rb 2 CO 3 with As 2 Se 3 and black selenium leads to the formation of Rb 3 AsSe 4 and the new selenidoarsenate(V) Rb 3 AsSe 4 · 2Se 6 (1), which crystallizes in the cubic space group Fd3̄ (No. 203) with a = 16.660(2) Å, V = 4624.1(1) Å , Z = 8. The structural features are isolated tetrahedral AsSe 4 3- anions and Se 6 rings in a chair conformation. Whereas the similar reaction with Cs 2 CO 3 only affords the known selenides Cs 3 AsSe 4 and Cs 4 Se 16 , replacement of As 2 Se 3 by As 2 Te 3 leads to a compound with similar lattice constants to 1 (Fd3̄, a = 17.275(2) A), containing disordered AsSe 4 3- and As 2 Se 4 2- anions, the latter of which exhibit a four-membered As 2 Se 2 ring with m-positioned terminal selenium atoms. The six-membered chalcogen ring is likewise disordered with Se and Te site occupation factors of respectively 0.333 and 0.667 with the result that 2 can be formulated as Cs 3 AsSe 4 · 2Cs 2 As 2 Se 4 · 6Te 4 Se 2 . 2 provides the first example of a Te x Se 6-x ring to be characterized in the solid state.