STRUCTURAL CHEMISTRY OF A NEW TERNARY URANIUM RHODIUM PHOSPHIDE - U-6 RH-20 P-13

The new compound U//6Rh//2//0P//1//3 has been prepared, starting from the elemental components. Its crystal structure, determined from single-crystal X-ray data is isotypic with Zr//6Ni//2//0P//1//3, hexagonal symmetry, space group P6-C//3//h with one formula unit per cell and the lattice constants a equals 13. 259(7) A, c equals 3. 896(7) A, c/a equals 3. 40, V equals 685 A**3. The structure is closely related to those of binary M//2P and ternary rare earth-transition metal phosphides and can be usefully described in the same way on the basis of the phosphorus lattice. U//6Rh//2//0P//1//3 is the first compound presenting a uranium insertion in a triangular prismatic phosphorus site, opening the way to the finding of numerous new uranium-transition metal pnictides.