Thiocyanate Compounds of [Nb 6 Cl 12 ] 2+ : The structure of A 4 [Nb 6 Cl 12 (NCS) 6 ](H 2 O) 4 (A = K, Rb, NH 4 )

New compounds of the general formula A 4 [Nb 6 Cl 12 (NCS) 6 ](H 2 O) 4 (A = K, Rb, NH 4 ) were synthesized from Nb 6 Cl 14 and ASCN in aqueous solutions. X‐ray structure refinements were performed on single‐crystal data of the three compounds. They are isotypic and crystallize with the space group P 1 (Z = 1) and the lattice parameters: a = 877.9(3) pm, b = 1176.6(3) pm, c = 1187.0(3) pm, α = 114.29(1)°, β = 98.96(2)°, γ = 100.91(2)° for K 4 [Nb 6 Cl 12 (NCS) 6 ](H 2 O) 4 ( 1 ); a = 887.6(3) pm, b = 1184.0(4) pm, c = 1195.4(4) pm, α = 114.95(2)°, β = 98.84(2)°, γ = 101.31(2)° for Rb 4 [Nb 6 Cl 12 (NCS) 6 ](H 2 O) 4 ( 2 ) and a = 886.0(4) pm, b = 1181.1(6) pm, c = 1183.9(6) pm, α = 114.49(2)°, β = 99.48(3)°, γ = 101.53(1)° for (NH 4 ) 4 [Nb 6 Cl 12 (NCS) 6 ](H 2 O) 4 ( 3 ). Each centrosymmetric [Nb 6 Cl 12 (NCS) 6 ] 4− ion of the isotypic compounds contains six terminal thiocyanate groups being bound to the corners of the octahedral niobium cluster through the nitrogen atoms (d NbN = 221.5(6)–224.3(6) pm, bond angles NbNC 168.6(5)–176.4(6)°). The [Nb 6 Cl 12 (NCS) 6 ] 4− ions are linked via AS and ACl interactions with the A cations. Half of the cations occur to be disordered along two crystallographic sites.