Alkaline metal oxoantimonates(III), A3[SbO3] (A = K or Cs)

The two title trialkaline trioxoantimonates(III), tripotassium trioxoantimonate(III), K₃SbO₃], (I), and tricaesium trioxo­antimonate(III), Cs₃SbO₃], (II), crystallize in the cubic Na₃AsS₃] structure type in space group P2₁3. The structures show discrete Ψ-tetrahedral SbO₃]^3? anions with C_3v point-group symmetry. The Sb—O distances are 1.923 (4) Å in (I) and 1.928 (2) Å in (II), and the O—Sb—O bond angles are 99.5 (2)° in (I) and 100.4 (1)° in (II).