Synthesis and crystal structure of 4,7,13,16,21,24-hexaoxa-1,10-diazoniabicyclo[8.8.8]hexacosane sulfate tetrahydrate

Abstract

A hydrated salt of 2.2.2-cryptand and sulfuric acid [H2(Crypt-222)]2+ · SO 4 2− · 4H2O(I) was prepared and studied by X-ray diffraction. The structure of I (space group C2/c, a = 22.823, b = 9.610, c = 26.150 A, β = 107.71°, Z = 8) was solved by the direct method and refined by full-matrix least-squares in the anisotropic approximation to R = 0.056 for 4032 independent reflections (CAD4 automated diffractometer, λMoK α radiation). In the structure of I, the 2.2.2-cryptand dication (with approximate C 2 symmetry) has a rare exo-exo conformation where two H atoms at two N atoms are directed away from the cavity. The tetrahedral SO 4 2− anion is disordered over two orientations. In two water molecules, the H atoms are disordered, while in the other two water molecules all atoms are disordered. The crystal structure of I has an extensive three-dimensional system of ion-ion (intermolecular) hydrogen bonds in which infinite chains of alternating SO 4 2− anions and 2.2.2-dications can be distinguished.