Syntheses, structures, and comparisons of thallium uranium phosphites, mixed phosphate-phosphites, and phosphate

摘要

A new family of six thallium uranium phosphites and phosphates has been synthesized. Here there are three new thallium uranyl phosphites, Tl _2[(UO_2)(HPO_3)(H_2PO _3)]_21, Tl_2[(UO_2) _2(HPO_3)_3]·H_2O _2, and Tl _6[(UO_2)_5(H_2O)(HPO_3) _8]·2H_2O 3, a uranyl phosphate-phosphite, Tl _3[(UO_2)_2(H_(1.5)PO_4)(H _(0.5)PO_4)(H_(1.5)PO_3)_2] 4, a mixed uranium(VI)-uranium(IV) phosphate-phosphite, Tl_2[(UO _2)_2(U~(IV))(H_2O)(PO_4) _2(HPO_3)_2] 5, and, finally, a thallium uranium(IV) phosphate, Tl_2[U~(IV)(PO_4) _2] 6, which were hydrothermally synthesized using thallium carbonate, uranyl nitrate, and H_3PO_3 as initial reagents. The above phases were all isolated from mixtures and were characterized by single-crystal X-ray diffraction and solid-state UV-vis-NIR spectroscopy. Compounds 1, 2, 3, and 5 are isotypic to known topologies. Herein, we investigate these six new thallium compounds and explore the effects of the thallium carbonate concentration and time on the reduction of uranium, via the phosphite ligand, within the crystalline products observed and also examine how these thallium species relate in terms of unit cells, symmetry, and bonding to known uranium phases.