Synthesis and crystal structure of bis(2,2,2-cryptand potassium) tetrakis(isocyanato)cuprate(II)

A new complex compound, bis(2,2,2-cryptand potassium) tetrakis(isocyanato)cuprate(II), 2[K(Crypt-222)](+) [Cu(NCS)4](2-) was prepared and its crystal structure was studied by X-ray structural analysis. The structure includes one symmetrically independent complex cation [K(Crypt-222)](+) of a guest-host type and independent one half of [Cu(NCS)(4)](2-) anion. Through the center of the anion passes crystallographic symmetry axis 2, the approximate point symmetry of the anion is D (2), while the approximate point symmetry of the complex cation is D (3). The coordination polyhedron of the [Cu(NCS)(4)](2-) anion (four N atoms) conjugated with Cu2+ cation is a nonplanar square considerably screwed into a flattened tetrahedron. The K+ cation (coordination number 8) of the complex cation [K(Crypt-222)](+) is coordinated by all eight heteroatoms (6O + 2N) of the 2,2,2-cryptand ligand, and its coordination polyhedron can be described as bis-basecentered trigonal prism slightly screwed into an anti-prism.