The New Oxometallates Cs₄[FeO₃], Cs₄[ZnO₃] and Cs₃[BO₃] with Trigonal-planar Anions – Decomposition Products of Alkali Metal Suboxometallates

Abstract

Three new cesium oxometallates with trigonal-planar [MO 3 ] n− anions (M = Zn, Fe, B) were observed as products of reactions aimed at the formation of alkali metal suboxometallates A 9 MO 4 (A = Rb, Cs; M = Al, Ga, In, Fe, Sc), or as decomposition products thereof. Cs 4 [FeO 3 ], Cs 4 [ZnO 3 ] and Cs 3 [BO 3 ] crystallize with new structure types (Cs 4 [FeO 3 ]: triclinic, space group P1, a = 7.0652(1), b = 7.125(1), c = 9.939(2)Å, α = 80.74(2), β = 71.32(2), γ = 64.04(2) • , Z = 2, Cs 4 [FeO 3 ]: monoclinic, space group P2 1 /c, a = 7.146(4), b = 18.572(1), c = 7.050(4)Å, β = 115.47(4) • , Z = 4, Cs 3 [BO 3 ]: orthorhombic, space group Pnma, a = 10.967(1), b = 10.967(1), c = 10.353(1)Å). In all structures the trigonal-planar anions have no or low point symmetry, but deviate only marginally from ideal6m2 symmetry. The new crystal structures can be derived from simple and highly symmetrical packings of spheres or from known binary structure types.