Trimethyl[2-(2-methyl-2-propenoyloxy)ethyl]ammonium iodide (methacryloylcholine iodide)

The structure of the title compound, C9H18NO2+.I-, has been refined in the centrosymmetric space group Pnma, with the two ions set on a mirror plane and one choline methylene C atom statistically disordered on both sides of this plane. The acryloyl fragment and the choline chain are in antiperiplanar and intermediate between anticlinal and antiperiplanar conformations, respectively. The crystal packing is forced by interionic interactions only. The four C atoms of the quaternary ammonium groups and iodide anions are ordered in a dual tetrahedral fashion.