(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, λMoKα. 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.