The new oxometallates Cs _4[FeO _3], Cs _4[ZnO _3] and Cs _3[BO _3] with trigonal-planar anions - Decomposition products of alkali metal suboxometallates

摘要

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 _9MO _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 P-1, a = 7.0652(1), b = 7.125(1), c = 9.939(2) ?, α = 80.74(2), β = 71.32(2), γ = 64.04(2)?, Z = 2, Cs _4[FeO _3]: monoclinic, space group P21/c, a = 7.146(4), b = 18.572(1), c = 7.050(4) ?, 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) ?). In all structures the trigonal-planar anions have no or low point symmetry, but deviate only marginally from deal 6m2 symmetry. The new crystal structures can be derived from simple and highly symmetrical packings of spheres or from known binary structure types.