Crystal and molecular structures of the 18-crown-6 complex with potassium salt of N-(diisopropoxyphosphoryl)benzamide

The molecular and disordered crystal structures of the 18-crown-6 (18C6) co mplex with potassium salt of N-(diisopropoxyphosphoryl)benzamide (I) were s tudied by X-ray diffraction analysis (CAD-4 automated diffractometer, lambd a CuKalpha); space group P2(1)2(1)2(1), a = 8.588, b = 15.796, c = 22.996 A ngstrom, Z = 4. Structure I was solved by the direct method and refined by the full-matrix least-squares method in anisotropic approximation to R = 0. 078 for 1856 reflections. In the crystal, complex I exists as individual mo lecules of the host-guest type consisting of the crown ligand, the octacoor dinate K+ cation, and the bidentate organophosphorus anion. In crystal stru cture I, the 18C6 ligand is disordered over two nearby positions and has th e conformation with approximate D-3d symmetry.