Hydrogen positions in potassium pentaborate tetrahydrate as determined by neutron diffraction

Abstract

Neutron diffraction data obtained with single crystals of potassium pentaborate tetrahydrate have been analyzed using least squares methods. Apart from significant differences in the atomic coordinates of the hydrogen atoms, the structure is in agreement with recent X-ray work. The O—H distances in the hydroxyl groups are 1.012 ± 0.018 and 0.955 ± 0.020 Å. In contrast to the X-ray results, the geometry of the water molecule is normal for an inorganic hydrate with O—H distances of 0.954 ± 0.026 and 1.004 ± 0.018 Å and an H—O—H angle of 108 ± 2°.