Synthesis and Crystal Structure of Cesium Hexamminesodium Decahydro‐closo‐decaborate‐Ammonia(1/1), Cs[Na(NH3)6][B10H10]·NH3

CsNa(NH₃)₆]B₁₀H₁₀]·NH₃ was synthesised from cesium and disodium‐decahydro‐closo‐decaborate Na₂B₁₀H₁₀ in liquid ammonia, from which it crystallized in form of temperature sensitive colorless plates (triclinic, P1¯, a = 8.4787(7) Å, b = 13.272(1) Å, c = 17.139(2) Å, α = 88.564(1)°, β = 89.773(1)°, γ = 81.630(1)°, V = 1907.5(3) ų, Z = 4). The compound is the first example of an alkali metal boranate with two different types of cations. The decahydro‐closo‐decaborate dianions B₁₀H₁₀]^2— and the cesium cations form a equation/tex2gif-stack-1.gifCs₂(B₁₀H₁₀)₂]^2— layer parallel to the ac plane. These layers are separated by N—H···N‐hydrogen bonded hexamminesodium cations.