Structure determination of CuTh2(PO4)(3)

The crystal structure of CuTh2(PO4)(3), copper dithorium triphosphate, has been solved ab initio from conventional monochromatic X-ray powder diffraction and refined with neutron powder diffraction data. The symmetry is monoclinic, space group C2/c. The heavy-atom positions were found from a Patterson map calculated from integrated intensities extracted by whole-pattern fitting. Successive Fourier syntheses were used to locate the remaining atoms. The Th atoms and PO4 groups exhibit an arrangement related to that found in the M(I)Th(2)(PO4)(3) phases, with large sites in which the monovalent cations are located. In the title compound, these sites are elongated along a and shortened along b so that the Cu+ ions, located on inversion centres, are linearly bonded to two phosphate groups with two short Cu-O distances of 1.828 Angstrom.