Synthesis and crystal structure of 4,7,13,16,21,24-hexaoxa-1,10-diazoniabicyclo[8.8.8]hexacosane Bis(citrate) hydrate

Abstract

A crystalline salt of 2.2.2-cryptand and citric acid, 4,7,13,16,21,24-hexaoxa-1,10-diazoniabicyclo[8.8.8]hexacosane bis(citrate) hydrate [H2(Crypt-222)]2+·2(C6H7O7)− · 1.65H2O, was synthesized and studied by single crystal X-ray diffraction. In the crystal structure of this salt, the 2.2.2-cryptand dication is somewhat disordered, and its H atoms at two protonated N atoms are oriented inside the cryptand cavity. Two independent citrate anions are essentially different, as different COOH groups in them are deprotonated. The geometric parameters (bond lengths, bond angles, etc.) of the molecular ions and water molecules are determined with a relatively high accuracy. The structural units form a three-dimensional system of intermolecular (interionic) hydrogen bonds.