Ionothermal and Hydrothermal Flux Syntheses of Five New Uranyl Phosphonates

Abstract

Four new uranyl phosphonate compounds have been synthesized via ionothermal flux in the ionic liquids 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]) and 1-ethyl-3-methylimidazolium bromide ([Emim][Br]). [C8H15N2][UO2(C6H5PO3H)(C6H5PO3)] ([Bmim][UPhPO]), [C8H15N2]2[(UO2)4(C6H5PO3)3Cl4] ([Bmim][UPhPOCl]), [C8H15N2][UO2(HO3P(CH2)3PO3)] (α-[Bmim][UC3DPO]), and [C6H11N2]2[(UO2)2(p-C6H4(PO3H)2)3]·2H2O ([Emim][UPhDPO]) form one-dimensional chains, two-dimensional sheets, or three-dimensional frameworks. For comparison, analogous reactions were carried out hydrothermally, which lead to one new framework structure, [C8H15N2]2[(UO2)5(HO3P(CH2)3PO3)4] (β-[Bmim][UC3DPO]), and one previously characterized tubular uranyl phosphonate. It was found that the structure is equally dictated by the choice of flux method, the choice of ligand, and the choice of ionic liquid.