Synthesis, structure, and spectroscopy of two ternary uranium(IV) thiophosphates: UP2S9 and UP2S7 containing P2S92- and P2S 72- ligands

Abstract

The two ternary uranium thiophosphate compounds were isolated from polychalcogenide flux reactions. UP2S9 crystallizes in the tetragonal space group P42/mcm with two formula units per unit cell, where a = 7.762(1) and c = 9.691(3) Å. UP2S7 crystallizes in the orthorhombic space group Fddd with 16 formula units per unit cell, here a = 8.919(3), b = 15.198(4), and c = 30.104(9) Å. Both compounds were characterized through single crystal X-ray, UV-vis-NIR, and Raman spectroscopy. The structures of the two compounds are formed from [US 6]8- chains connected to each other by either the tridentate-chelating P2S94- in UP 2S9 or the P2S74- in UP2S7 resulting in 3D frameworks. These two ligands have different geometries, but they exhibit similar coordination modes, comparable to the ethane-like P2S64-. The uranium cations in both compounds can be assigned an unambiguous oxidation state of +4. The two compounds are semiconductors with nearly identical band-gaps of 1.41 eV. © 2013 American Chemical Society.