The Crystal and Molecular Structure of Palythine Trihydrate

Abstract

Abstract The molecular structure of palythine, C10H16N2O5, has been confirmed by means of an X-ray crystal analysis of its trihydrate. The crystals are monoclinic, with two formula units in a unit cell with dimensions of a=10.499, b=12.812, c=5.322 Å, and β=98.53°; the space group is P21. 1377 unique intensity data were collected on a four-circle diffractometer with LiF-monochromated Cu Kα radiation. The structure was solved by the Monte Carlo direct method, using the 20 strongest reflections as a starting set, and was refined by the block-diagonal least-squares method. The final R value was 3.1%. The molecular structure thus obtained corresponds to that proposed by Tsujino et al. and Takano et al. on the basis of the chemical evidence. Palythine exists as a zwitter ion in the crystal. The palythine and water molecules are connected by twelve types of hydrogen bonds, forming a three-dimensional hydrogen-bonded structure.