Synthesis and Characterization of Six New Quaternary Actinide Thiophosphate Compounds:  Cs8U5(P3S10)2(PS4)6 , K10Th3(P2S7)4(PS4)2, and A5An(PS4)3, (A = K, Rb, Cs; An = U, Th)

Six new actinide metal thiophosphates have been synthesized by the reactive flux method and characterized by single-crystal X-ray diffraction: Cs8U5(P3S10)2(PS4)6 (I), K10Th3(P2S7)4(PS4)2 (II), K5U(PS4)3 (III), K5Th(PS4)3 (IV), Rb5Th(PS4)3 (V), and Cs5Th(PS4)3 (VI). Compound I crystallizes in the monoclinic space group P21/c with a = 33.2897(1) Å, b = 14.9295(1) Å, c = 17.3528(2) Å, β = 115.478(1)°, Z = 8. Compound II crystallizes in the monoclinic space group C2/c with a = 32.8085(6) Å, b = 9.0482(2) Å, c = 27.2972(3) Å, β = 125.720(1)°, Z = 8. Compound III crystallizes in the monoclinic space group P21/c with a = 14.6132(1) Å, b = 17.0884(2) Å, c = 9.7082(2) Å, β = 108.63(1)°, Z = 4. Compound IV crystallizes in the monoclinic space group P21/n with a = 9.7436(1) Å, b = 11.3894(2) Å, c = 20.0163(3) Å, β = 90.041(1)°, Z = 4, as a pseudo-merohedrally twinned cell. Compound V crystallizes in the monoclinic space group P21/c with a = 13.197(4) Å, b = 9.997(4) Å, c = 18.189(7) Å, β = 100.77(1)°, Z = 4. Compound VI crystallizes in the monoclinic space group P21/c with a = 13.5624(1) Å, b = 10.3007(1) Å, c = 18.6738(1) Å, β = 100.670(1)°, Z = 4. Optical band-gap measurements by diffuse reflectance show that compounds I and III contain tetravalent uranium as part of an extended electronic system. Thorium-containing compounds are large-gap materials. Raman spectroscopy on single crystals displays the vibrational characteristics expected for [PS4]3-, [P2S7]4-, and the new [P3S10]5- building blocks. This new thiophosphate building block has not been observed except in the structure of the uranium-containing compound Cs8U5(P3S10)2(PS4)6.