Synthesis and Crystal Structure of Thorium Bis(hydrogenphosphate) Monohydrate

Microcrystals of Th(HPO4)2·H2O were hydrothermally obtained from a Th(NO3)4−CO(NH2)2−H3PO3−H2O system (T = 180 ºC). The structure [orthorhombic, Pbca, a = 9.1968(2) Å, b = 18.6382(2) Å, c = 8.7871(2) Å], unlike α-Zr(HPO4)2·H2O-type layered compounds, consists of a three-dimensional framework with PO4 tetrahedra coordinated to Th atoms. The water molecule is also coordinated to the Th atom and projected toward small channels running along the directions of the a and c axes. The ThO6O(w) environment could be described as a highly distorted pentagonal bipyramid.