[Sb11]3− and [As11]3−: Synthesis and Crystal Structure of Two New Ammoniates containing Trishomocubane‐like Polyanions

The ammoniates K(18‐crown‐6)(NH₃)₂]₃Sb₁₁ · 5.5NH₃ ( 1 ) and Cs(18‐crown‐6)]₂CsAs₁₁ · 8NH₃ ( 2 ) (18‐crown‐6 = 18C6: 1,4,7,10,13,16‐Hexaoxacyclooctadecan) were synthesized by either the reaction of K₃Sb₇ with SbPh₃ in liquid ammonia or by extraction of Cs₃As₁₁ with liquid ammonia. Single crystals were isolated and characterized by low temperature X‐ray structure analysis. K(18‐crown‐6)(NH₃)₂]₃Sb₁₁ · 5.5NH₃ crystallizes in the space group with a = 13.31(2) Å, b = 15.161(2) Å, c = 22.521(3) Å, α = 99.23(1)°, β = 100.99(1)° and γ = 105.03(1)°. Cs(18‐crown‐6)]₂CsAs₁₁ · 8NH₃ crystallizes in the monoclinic space group C2/c with a = 20.009(3) Å, b = 17.024(1) Å, c = 19.838(2) Å and β = 119.732(9)°. While 1 contains isolated Sb₁₁]^3? anions and K(18‐crown‐6)(NH₃)₂]⁺ complexes, cesium–arsenic contacts lead to one–dimensionally infinite chains in 2 .