Bis[(2.2.2-cryptand)potassium] tetrakis(isothiocyanato)cobalt(II) ethanol solvate with the 22% RbBr molar admixture: Synthesis and crystal structure

A new crystalline complex, bis(2.2.2-cryptand)potassium] tetrakis(isothiocyanato)cobalt(II) ethanol solvate of the composition 2K_0.89Rb_0.11(Crypt-222)]⁺ Co(NCS)_3.78Br_0.22]^2? EtOH (I), was synthesized with 22 mol % RbBr and studied by X-ray diffraction. Complex I contains two mixed host-guest complex cations and the mixed complex anion. The triclinic structure of complex I (space group P1, a = 12.060 Å, b = 12.156 Å, c = 12.264 Å, α = 80.45°, β = 61.28°, γ = 71.98°, Z = 1) was solved by a direct method and refined by the full-matrix least squares in the anisotropic approximation to R = 0.066 for all 4400 independent reflections (CAD-4 automated diffractometer, λMoK _α radiation). The Co(NCS)_3.78Br_0.22]^2? anion is tetrahedral, and its two SCN^? ligands are partially replaced by two Br^? ligands. In structure I, two independent host-guest complex cations K′(Crypt-222)]⁺ (K′ = (K_{1 ? δ} Rb_δ)⁺) are almost identical inverted reflection of each other and have approximate D ₃ symmetry. Their mixed cation K′ is coordinated by all eight heteroatoms (6O + 2N) of the 2.2.2-cryptand ligand, and the coordination polyhedron K′ is a dibase-centered trigonal prism (coordination number eight) slightly distorted toward an antiprism.