Refinement of the crystal structure of sinigrin

The crystal structure of sinigrin (potassium myronate), KC_(10)H_(16)NO_9S_2. H_2O, has been refined on the of three-dimensional intensity data collected on an automated diffractometer. The final agreement is 0·056 for 1906 reflections, and the estimated standard deviations in the atomic coordinates of the , N, and 0 atoms are about 0·004 Å. The absolute configuration of the anion was confirmed from dispersion effects. The crystals are orthorhombic with space group P212121. The unit-cell of a new crystal are ɑ = 8·265 (1), b = l1·440(3), and c = 17·757 (3)A. An appreciable increase the length of the c axis occurred during irradiation of the crystal. In addition, the vinyl group the myronate ion appears to undergo large thermal motions. The distances between vinyl groups of myronate ions are such that a photopolymerization reaction between them would be possible, might explain these two observations.