Crystal growth, structural characterization, cation–cation interaction classification, and optical properties of uranium(vi) containing oxychlorides, A₄U₅O₁₆Cl₂ (A = K, Rb), Cs₅U₇O₂₂Cl₃, and AUO₃Cl (A = Rb, Cs)

Abstract

Single crystals of five new uranyl oxychlorides exhibiting novel layer topology, CCIs, chain structures, and/or luminescence were grown from molten chlorides. A comprehensive CCI classification is presented.

Synthesis, Crystal Structure, and Optical Properties of a New Complex Uranium Oxychloride, KUO3Cl

“…The uranium-containing oxychloride materials also follow this trend, with the majority having two-dimensional (2D) sheet structures; however, four of the reported compounds exhibit cation-cation interactions [10,11], where the axial oxygen atoms are further coordinated to other uranyl ions. It is well known that uranyl compounds often exhibit luminescence [15], however, this property is often thermally quenched in the oxides [16].…”

“…The crucible was loaded into a programmable furnace and heated at a rate of 10°C/min to 900°C, held for 12 h, then cooled to 550°C at a rate of 0.1°C/min followed by rapid cooling to room temperature by shutting off the furnace. The product contained a mixture of yellow crystals of KUO 3 Cl and orange crystals of K 4 U 5 O 16 Cl 2 , which we reported on previously [10]. The yellow, needlelike crystals of KUO 3 Cl were isolated from the solidified flux by dissolving the flux in water, assisted by sonication, and collected by vacuum filtration.…”

“…It is well known that uranyl compounds often exhibit luminescence [15], however, this property is often thermally quenched in the oxides [16]. With addition of chloride into the structure, the luminescence is no longer quenched in some cases [10]. Due to the interesting structural elements already reported and the expressed optical properties, it is of great interest to further study this class of materials.…”

“…There are 20 structurally characterized uranium-containing oxychlorides reported in the literature [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Seventeen of the known compounds contain uranium in the ?6 oxidation state, by far the most common oxidation state amongst uranium-containing oxides and related materials.…”

Single Crystal Growth and Structural Characterization of a Novel Mixed-Valent Ternary Uranium Oxide, K8U7O24

“…Interestingly, the axial oxygen atoms in U(1)O 6 are cornersharing with the U(2) atoms, which suggest the presence of an unconventional cation-cation interaction (CCI), because U(2) does not have a uranyl environment. U(1) exhibits a Type 3 CCI, according to the labeling convention presented by Read, et al [31].…”