Synthesis and crystal structure of 1,10-diazonia-18-crown-6 diiodide dihydrate

Crystalline 1,10-diazonia-18-crown-6 diiodide dihydrate was synthesized and studied by single crystal X-ray diffraction. The salt exists in the crystal in the form of separate centrosymmetrical ionic molecules [(H(2)DA18C6)(2+)center dot 2I(-)center dot 2H(2)O] whose components are held together by hydrogen bonds and electrostatic attraction forces. The centrosymmetric dication DA18C6 (with two protonated nitrogen atoms) has a crown conformation with approximate D-3d symmetry. The iodide ions are arranged at the nitrogen atoms (one above and the other below) of the DA18C6 dication, and two water molecules are arranged above and below its symmetry center. Each water molecule is disordered over two positions with occupancies of 0.65 and 0.35.