ScFe5P3, ScRu6P4, U2Mo30P19, and Other Ternary Phosphides with a Metal to Phosphorus Ratio close to 2:1

The title compounds and several other new ternary phosphides – all with closely related crystal structures – were prepared mostly by using elemental tin as a flux. ScFe5P3, Sc(Ta0.18Fe0.82)Fe4P3, and ZrFe5P3 are isotypic with YCo5P3. The crystal structure of the tantalum containing compound was determined from single-crystal X-ray counter data: space group Pnma, a = 1212.5(2) pm, b = 363.0(2) pm, c = 1052.2(2) pm with a residual R = 0.036 for 505 unique structure factors and 30 variable parameters. The Ta atoms occupy only that Fe site with the highest coordination number. The crystal structure of ScRu6P4 (α-UCr6P4 type) was refined from single-crystal data: Pequation imagem2, a = 690.0(2) pm, c = 362.5(3) pm; R = 0.023 for 226 Fo and 15 variables. The same structure was also found from Guinier powder data for ErRu6P4 and ZrCr6P4. However, single-crystal film data for the latter compound suggest a superstructure with a doubling of the hexagonal axis. The new compound Nd2Ru12P7 is shown from Guinier powder data to crystallize with a hexagonal Zr2Fe12P7 type structure. X-ray powder data also confirm Zr2Ru12P7 and SmCo3P2 to crystallize with Zr2Fe12P7and HoCo3P2 type structures, respectively. The crystal structure of the phosphide U2Cr30P19 is confirmed to be isotypic with Zr2Cr30P19. The same structure was found for the new compound U2Mo30P19. The crystal structures of these and other compounds with a metal to phosphorus ratio close to 2:1 are briefly discussed including that of LiCo6P4