Complex Uranyl Dichromates Templated by Aza-Crowns

Abstract

Three new uranyl dichromate compounds templated by aza-crown templates were obtained at room temperature by evaporation from aqueous solutions: 4 (3). The use of aza-crown templates made it possible to isolate unprecedented and complex one-dimensional units in 2 and 3, whereas the structure of 1 is based on simple uranyl-dichromate chains. It is very likely that the presence of relatively large organic molecules of aza-crown ethers does not allow uranyl chromate chain complexes to condense into the units of higher dimensionality (layers or frameworks). In general, the formation of 1, 2, and 3 is in agreement with the general principles elaborated for organically templated uranyl compounds. The negative charge of the [(UO 2 )(Cr 2 O 7 ) 2 (H 2 O)] 2− , [(UO 2 ) 2 (CrO 4 ) 2 (Cr 2 O 7 ) 2 (H 2 O)] 4− and [(UO 2 ) 3 (CrO 4 ) 4 (Cr 2 O 7 ) 2 ] 6− one-dimensional inorganic motifs is compensated by the protonation of all nitrogen atoms in the molecules of aza-crowns.

Mild hydrothermal crystal growth of new uranium(IV) fluorides, Na3.13Mg1.43U6F30 and Na2.50Mn1.75U6F30: Structures, optical and magnetic properties

“…In fact, many silicates and germanates containing U(IV) were prepared via hydrothermal methods involving the reduction of U(VI) by aluminum metal; however, this method requires extremely high temperatures and pressures that are difficult to achieve in a regular laboratory setting [31][32][33][34][35][36]. On the other hand, numerous organic reducing agents (solvents) are also effective for the creation of U(IV) containing compounds; however, this approach often results in organically templated U (IV) containing compounds where the organic group is incorporated into the crystal structures [37][38][39][40][41][42][43][44][45][46]. Thus, it continues to be a challenge to synthesize novel inorganic solids containing U(IV).…”