Crystal and molecular structure of iodoprotatrane: Tris(2-hydroxyethyl)ammonium iodide

By X-ray diffraction the crystal and molecular structure of iodoprotatrane (tris(2-hydroxyethyl)ammonium iodide I[HN(CH2CH2OH)(3)](+) (IP) at 120 K and 293 K is determined. The IP cation, as in all protatranes, has the endo conformation. The N-H bond is surrounded by three CH2CH2OH groups. The stability of this configuration is explained by the intramolecular trifurcated inductive interaction with three oxygen atoms through the space of the nitrogen atom. In the IP crystal packing, each iodine anion is linked by three strong OH...I (2.63 ) and three weak I...H (3.13 ) hydrogen bonds with six cations from the CH2N group. This indicates a greater nucleophilicity of the iodine atom