(18-crown-6)potassium tris(thiocyanato)nickelate(II): Synthesis and crystal structure

A new crystalline complex, (18-crown-6)potassium tris(thiocyanato)nickelate(II), [Ni(SCN)₃K(18-crown-6)] _n (I) was synthesized and studied by X-ray diffraction: space group Cmc2₁, a = 14.749, b = 15.045, c = 10.216 Å, Z = 4, direct method, least-squares full-matrix refinement in anisotropic approximation to R = 0.022 on 2214 independent reflection, CAD-4 automated diffractometer, λMoK _α. In crystal structure I, the [Ni(SCN)₃] _n ^? chains are directed along the axis z with the host-guest [K(18-crown-6)]⁺ fragments attached through the weak K-S bonds to the chains at the side. The complex cations and anions lie in crystallographic plane m. The Ni²⁺ cation has a distorted octahedral coordination. The coordination polyhedron of the K⁺ cation is a distorted hexagonal pyramid with six O atoms of the 18-crown-6 ligand in the base and bifurcate axial vertex at the S and S′ atoms of two SCN^? ligands.