Description and Structure of New Compounds Ln//3MO//5XCl//3 (Ln EQUVLNT La, Ce, Pr, Nd, Th; M EQUVLNT Ta, Nb; X EQUVLNT O, OH, F).

Article abstract of DOI:10.1016/0022-5088(88)90076-8

La//2ThTaO//6Cl//3, a representative of a group of isostructural Ln//3MO//5XCl//3-type compounds with Ln EQUVLNT La - Nd, Th, X EQUVLNT O, OH, F and M EQUVLNT Ta, Nb, crystallizes in the hexagonal space group P6//3/m. The compound was prepared by the interaction of ThO//2, LaTaO//4 and LaCl//3. Single crystals were obtained by chemical transport reactions (1080 yields 940 degree C) using chlorine as the transport agent. The structure consists of TaO//6 polyhedra with an unusual trigonally prismatic environment for the Ta. La and Th are randomly distributed over the 6(h) sites with a coordination number CN equals 10.