Crystal Structure of the Diaqua(1,10-Diaza-18-Crown-6) (Tetrafluorosuccinato-O)barium Complex

Abstract

The diaqua(1,10-diaza-18-crown-6)(tetrafluorosuccinato-O)barium complex [Ba(DA18C6)(C4F4O4)(H2O)2] (I) is synthesized and studied using X-ray diffraction analysis: space group P21/n, a = 16.342 A, b = 8.989 A, c = 17.087 A, β = 107.09°, Z = 4. The structure was solved by the direct method and refined by the full-matrix least squares method in anisotropic approximation to R = 0.075 for all 3515 unique reflections (CAD4 automated diffractometer, λMoKα). Complex I exists in the crystal as individual host–guest molecules of the aforementioned composition. The Ba2+ cation (coordination number 9) is located in the void of the DA18C6 macrocycle and is coordinated by its six O and N heteroatoms. It is also coordinated by the O atom of the tetrafluorosuccinate ligand and the O atom of the water molecule on one side of the macrocycle and by the O atom of the second water molecule on the other macrocycle side. The DA18C6 ligand has a crown conformation with approximate D3d symmetry. The complex molecules in the crystal are combined into infinite two-dimensional layers by intermolecular hydrogen bonds.