title: From order to disorder and back again: in situ hydrothermal redox reactions of uranium phosphites and phosphates.
abstract: Five new uranium phosphites, phosphates, and mixed phosphate-phosphite compounds were hydrothermally synthesized using H(3)PO(3) as an initial reagent. These compounds are Cs(4)[(UO(2))(8)(HPO(4))(5)(HPO(3))(5)]·4H(2)O (1), Cs[U(IV)(PO(4))(H(1.5)PO(4))](2) (2), Cs(4)[U(IV)(6)(PO(4))(8)(HPO(4))(HPO(3))] (3), Cs(10)[U(IV)(10)(PO(4))(4)(HPO(4))(14)(HPO(3))(5)]·H(2)O (4), and Cs(3)[U(IV)(4)(PO(4))(3)(HPO(4))(5)] (5). The first contains uranium(VI) and the latter four uranium(IV). Of the U(IV) structures, two have extensive disordering among the cesium cation positions, one of which also contains disordering at some of the phosphate-phosphite positions. These intermediate compounds are bookended by nondisordered phases. The isolation of these transitional phases occurred at the higher of the pH conditions attempted here. Both the starting pH and the duration of the reactions have a strong influence on the products formed. Herein, we explore the second series of in situ hydrothermal redox reactions of uranyl nitrate with phosphorous acid and cesium carbonate. The isolation of these disordered crystalline products helps to illuminate the complex reaction pathways that can occur in hydrothermal syntheses.
authors.affiliation: Department of Chemistry and Biochemistry, Florida State University, 102 Varsity Way, Tallahassee, Florida 32306-4390, United States.
authors.forename: Eric M
authors.initials: EM
authors.lastname: Villa
authors.forename: Connor J
authors.initials: CJ
authors.lastname: Marr
authors.forename: Juan
authors.initials: J
authors.lastname: Diwu
authors.forename: Evgeny V
authors.initials: EV
authors.lastname: Alekseev
authors.forename: Wulf
authors.initials: W
authors.lastname: Depmeier
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Albrecht-Schmitt