Aquabis(dibenzo-18-crown-6)(tetrabromocuprato(II))dipotassium: Synthesis and crystal structure

The novel complex [K(Db18C6)(H₂O)]⁺[K(Db1)] ⁺(CuBr₄)^2? (I) was obtained. Its crystal structure (space group P2₁/c, a = 17.970 Å, b = 29.838 Å, c = 9.074 Å, β = 103.11°, Z = 4) was studied by X-ray diffraction analysis, solved by the direct method, and refined by the least-squares method in the anisotropic approximation to R = 0.098 from 6220 independent reflections (CAD-4 automated diffractometer, λMo Kα). In both “guest-host” complex ions, the K⁺ cation is in the cavity of the crown ligand Db18C6 and is coordinated by all its O atoms, as well as by a Br atom of the complex anion [CuBr₄]^2? or the water O atom. The coordination of either K⁺ cation is extended to a hexagonal bipyramid by a weak K⁺ → π((Cdddot ---C)) bond to two C atoms of the benzene ring of the adjacent ligand Db18C6. In the crystal, the complex anions and cations are united into infinite double chains through the above contacts and the interion hydrogen bonds O-H…Br.