Crystal structure of the unusual disproportionated sodium thiocyanate complex with 1,4,7,10-tetraoxa-13,16-diazacyclooctadecane-12,17-dione and the structure of the free crown ligand

Crystals of free 1,4,7,10-tetraoxa-13,16-diazacyclooctadecane-12,17-dione (I) and its unusual complex with sodium thiocyanate (II) were studied by X-ray crystallography. Crystals I are monoclinic: space group P2(1)/c, a = 9.029, b = 21.572, c = 8.430 Angstrom, beta = 117.74 degrees, Z = 4(C12H22N2O6) Crystals II are base-centered monoclinic: space group Cc, a = 13.547, b = 15.295, c = 26.083 Angstrom, beta = 93.70 degrees, Z = 12[C12H22N2O6. NaNCS]. Structures I and II were solved by direct method and refined by full-matrix least-squares method in anisotropic (isotropic for H atoms) approximation to R = 0.044 (I) and 0.034 (II) for 2742 (I) and 5357 (II) reflections, respectively. In the asymmetric part of the unit cell of II, three structural units [L . NaNCS] are disproportionated into two different oppositely charged complexes [L . Na(NCS)(2)](-) and [(L . Na)(2)NCS](+), where L is crown ligand I. The Na+ cation in the first complex is six-coordinated, and both Na+ cations in the second complex are seven-coordinated.