Thiocyanate Compounds of [Nb6Cl12]2+: The structure of A4[Nb6Cl12(NCS)6](H2O)4 (A = K, Rb, NH4)

Abstract

AbstractNew compounds of the general formula A4[Nb6Cl12(NCS)6](H2O)4 (A = K, Rb, NH4) were synthesized from Nb6Cl14 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 P1 (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 K4[Nb6Cl12(NCS)6](H2O)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 Rb4[Nb6Cl12(NCS)6](H2O)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 (NH4)4[Nb6Cl12(NCS)6](H2O)4 (3). Each centrosymmetric [Nb6Cl12(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 (dNbN = 221.5(6)–224.3(6) pm, bond angles NbNC 168.6(5)–176.4(6)°). The [Nb6Cl12(NCS)6]4− ions are linked via AS and ACl interactions with the A cations. Half of the cations occur to be disordered along two crystallographic sites.