Crystal structure of phenacylkojate [2-(hydroxymethyl)-5-phenacyl-4H-pyran-4-one] monohydrate and comparison with some of its complexes with alkali-metal salts

Abstract

The structure of the title compound has been determined by three-dimensional X-ray crystal-structure analysis. Crystals are monoclinic, space group P2₁/c, with unit-cell dimensions a= 7·883(8), b= 18·781(5), c= 9·649(6)Å, β= 112·99(8)°, Z= 4. The structure was solved by direct methods and refined by full-matrix least-squares to R 0·044 for 1063 independent diffractometer observations.

The crystal structure is held together by a network of hydrogen bonds involving the water molecules and the carbonyl and hydroxy-groups of the phenacylkojate molecules. The phenacylkojate molecules are approximately planar and the water molecules occupy the same positions relative to the ligands as the cation in the alkali-metal complexes. Comparison with known crystal structures of the complexes shows the conformation of the ligand molecule to be similar throughout apart from the position of the hydroxy-group. The results show no simple trend relating anion and cation size to overall crystal structure but some indication is given of the probable arrangements in the other complexes with alkali-metal halides.