Observation of an Unusual Uranyl Cation-Cation Interaction in the Strongly Fluorescent Layered Uranyl Phosphates Rb6[(UO2)7O4(PO4)4] and Cs6[(UO2)7O4(PO4)4]

Christian A Juillerat; Emily E Moore; Theodore Besmann; Hans-Conrad Zur Loye

doi:10.1021/acs.inorgchem.8b00302

Observation of an Unusual Uranyl Cation-Cation Interaction in the Strongly Fluorescent Layered Uranyl Phosphates Rb₆[(UO₂)₇O₄(PO₄)₄] and Cs₆[(UO₂)₇O₄(PO₄)₄]

Inorg Chem. 2018 Apr 2;57(7):3675-3678. doi: 10.1021/acs.inorgchem.8b00302. Epub 2018 Mar 21.

Authors

Christian A Juillerat¹, Emily E Moore¹, Theodore Besmann¹, Hans-Conrad Zur Loye¹

Affiliation

¹ Department of Chemistry and Biochemistry and the Center for Hierarchical Wasteform Materials (CHWM) , University of South Carolina , Columbia , South Carolina 29208 , United States.

PMID: 29561156
DOI: 10.1021/acs.inorgchem.8b00302

Abstract

Single crystals of two new uranyl phosphates, A₆[(UO₂)₇O₄(PO₄)₄] (A = Cs, Rb), featuring cation-cation interactions (CCIs) rarely observed in uranium(VI) compounds were synthesized by molten flux methods. This structure crystallizes in the triclinic space group P1̅ with lattice parameters, a = 9.2092(4) Å, b = 9.8405(4) Å, c = 10.1856(5) Å, α = 92.876(2)°, β = 95.675(2)°, and γ = 93.139(2)° for A = Cs and a = 9.2166(9) Å, b = 9.3771(10) Å, c = 10.1210(11) Å, α = 89.981(4)°, β = 96.136(4)°, and γ = 92.790(4)° for A = Rb. The optical properties are reported for both compounds and compared to a layered uranyl phosphate, K₄[(UO₂)₃O₂(PO₄)₂], having a similar phosphuranylite-based structure but no CCIs. Partial ion exchange of Cs and Rb cations into the Rb₆[(UO₂)₇O₄(PO₄)₄] and Cs₆[(UO₂)₇O₄(PO₄)₄] structures, respectively, was achieved.