Precision of a crystal structure derived from a synchrotron X-ray powder pattern. The structure of Barium oxalate hydrate, BaC2O4·2H2O

Abstract The crystal structure of barium oxalate hydrate, BaC 2 O 4 ·2 H 2 O , was reinvestigated using a synchrotron X-ray powder pattern and a single crystal X-ray data set. The compound is monoclinic, a = 7.538(1), b = 11.062(1), c = 7.105(1) A , β = 105.42(1) °, space group P2 1 /c, with Z = 4. The precision of the structure arrived at with the synchrotron X-ray powder pattern is not as high as that obtained with the single crystal X-ray data. The barium atoms are bonded to the, oxalate ions and to the water molecules with nine barium oxygen bonds in the range 2.71(1)–2.97(1) A. The structure has hydrogen bonds in the range 2.72(2)–2.91(2) A, and the oxalate ion has only a minor deviation from planarity.