Uranyl-organic hybrids designed from hydroxyphosphonate

Abstract

A series of phosphonate-based uranyl-organic hybrids has been assembled based on the reaction of uranyl cations with 2,5-dihydroxy-1,4-benzenediphosphonic acid in the presence of a variety of alkali metal and organoammonium cations: K[(UO2)2F2{H0.5O3PC6H2(OH)2PO3H0.5}](H2O)2 (1), Cs[(UO2)2{H0.75O3PC6H2(OH)2PO3H0.75}](H2O)4·2H2O (2), [(CH3)4N]2[UO2{HO3PC6H2(OH)2PO3H}2] (3), [(CH3CH2)4N][UO2F{HO3PC6H2(OH)2PO3H}] (4), and [(CH3CH2)2N(CH3)2][UO2F{HO3PC6H2(OH)2PO3H}] (5). In compounds 1, 4, and 5, chains of UO5F2 pentagonal bipyramids are linked by the hydroxyphosphonate moiety into three-dimensional frameworks, and compound 4 is isostructural with 5. However, the structures of 2 and 3 are composed of monomeric UO7 pentagonal bipyramids assembled to form layered structural units. Additional steric influences from the -OH groups appended on the diphosphonate species play a vital role in directing the structure topologies.