Zur Kenntnis des Natriumthioferrates(III)

Cs[FeSe2], Cs3[FeSe2]2, and Cs7[Fe4Se8]: Missing Links of Known Chalcogenido Ferrate Series

“…contrast to the isopunctal Na 3 (10), b = 879.71 (5), c = 1717.03(10) pm, β = 117.890(2)°, Z = 4, R 1 = 0.0816] is isostructural both to the cesium sulfido and tellurido compound. The structure contains oligomeric moieties of four edge sharing [FeSe 4 ] tetrahedra forming slightly distorted tetrahedral clusters [Fe 4 Se 8 ] 7-, which are surrounded by a cube of 26 Cs cations.…”

“…[5,39] Its orthorhombic structure of space group I222 was deduced from fibre diffraction patterns by Boller and Blaha as early as 1983, [5] [13,14] ). The authors already noticed the similarity to the Ibam structure of the K 2 [ZnO 2 ]-type, i.e.…”

“…[1][2][3][4] The compounds with a Q:Fe ratio of 2:1 belong to two different classes: The large series of Fe III and Fe II/III mixed-valent chain ferrates exhibit hexagonal rod packings of linear or slightly buckled infinite chains of edge-sharing tetrahedra 1 ϱ [FeQ 4/2 ] n-. [5][6][7][8][9][10][11][12][4][5][6][7][8][9][10][11][12][13][14] The second class are salts containing cubane-type clusters . For numbers referring the structure type cf.…”

“…The general compound series A 1+x [Fe Figure 1): While oxido compounds of this type exhibit cristobalite-like networks of corner-sharing [FeO 4 ] tetrahedra, [20][21][22] the respective sulfido and selenido ferrates, which are observed for the whole alkali element series from Na (S) and K (Se) to Cs [5][6][7][8][9][4][5][6][7][8][9]23] contain linear chains of edge-sharing tetrahedra; tellurido ferrates(III) of this composition are unknown. The recently prepared first chain ferrates(II), Na 2 [FeS 2 ] and Na 2 [FeSe 2 ] [13,14] (x = 1, compound 5 in Figure 1), round out the series.…”

Some applications of the bond valence model to transition metal chalcogenides

“…In cases of more rigid frameworks strong deviations may indicate a squeezed condition as in NaFeS 2 with V Na = 1.83. This phase is metastable [15]. Too small bond valence sums indicate a rattling condition (the cation is too small to fill the cavity), which may be accompanied by some disorder, as it is the case in K[CuMoS 4 ] and ␣-or ␤-K[CuWS 4 ] [16] with V K ≈0.8.…”