Title

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)

Document Type

Article

Subject Area(s)

Chemistry

Abstract

Single crystals of five new alkali metal uranium oxychlorides, K4U5O16Cl2, Rb4U5O16Cl2, Cs5U7O22Cl3, RbUO3Cl, and CsUO3Cl, have been grown from molten chloride fluxes and structurally characterized by single crystal X-ray diffraction. All of the materials are monoclinic. The first three crystallize in the space group P21/n and exhibit a 2D layered structure with a novel layer topology, consisting of UO6, UO7, and UO4Cl2 polyhedra and cation–cation interactions (CCIs) within the plane of the uranyl sheet. A general cation–cation classification scheme is presented. RbUO3Cl and CsUO3Cl crystallize in the space group P21/m and exhibit 1D zipper-like chains of UO5Cl2 polyhedra. The lattice parameters of the new oxychlorides are: K4U5O16Cl2, a = 9.9574(4) Å, b = 6.9766(3) Å, c= 14.3920(6) Å, and β = 105.7690(10)°; Rb4U5O16Cl2, a = 10.2164(4) Å, b = 7.0160(3) Å, c= 14.4930(5) Å, and β = 103.8290(10)°; Cs5U7O22Cl3, a = 10.6214(5) Å, b = 18.1071(8) Å, c= 16.0857(7) Å, and β = 102.9850(10)°; RbUO3Cl, a = 7.3602(6) Å, b = 4.1127(3) Å, c = 8.5556(7) Å, and β = 104.602(2)°; CsUO3Cl, a = 7.7768(4) Å, b = 4.1245(2) Å, c = 8.7701(5) Å, and β = 105.4680(10)°. The materials were further characterized by UV-vis reflectance spectroscopy and fluorescence spectroscopy.

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