Phosphonoacetate as a Ligand for Constructing Layered and Framework Alkali Metal Uranyl Compounds

Abstract

The hydrothermal reactions of KCl, RbCl, CsOH, and CsCl with phosphonoacetic acid and uranium trioxide at 180 degrees C for three to five days results in the formation of five different crystalline uranyl carboxyphosphonates, K[(UO(2))(2)(PO(3)CH(2)CO(2))(PO(3)CH(2)CO(2)H)(H(2)O)] x H(2)O, Rb[(UO(2))(2)(PO(3)CH(2)CO(2))(PO(3)CH(2)CO(2)H)(H(2)O)] x H(2)O, Cs[(UO(2))(2)(PO(3)CH(2)CO(2))(PO(3)CH(2)CO(2)H)(H(2)O)] x H(2)O, Cs[(UO(2))(PO(3)CH(2)CO(2))], and Cs(3)[(UO(2))(4)(PO(3)CH(2)O(2))(2)(PO(3)CH(2)CO(2)H(0.5))(2)] x nH(2)O, respectively. In all compounds, the UO(2)(2+) moieties are bound by phosphonate and carboxylate forming pentagonal bipyramidal environments around the uranium centers. At low pH, some of the carboxylate portions of the phosphonoacetate are protonated. The addition of hydroxide removes these protons, and a different structure is adopted. In contrast to all other uranyl carboxyphosphonates, Cs(3)[(UO(2))(4)(PO(3)CH(2)O(2))(2)(PO(3)CH(2)CO(2)H(0.5))(2)] x nH(2)O adopts a three-dimensional network structure with large channels along the c axis that house the Cs(+) cations.

Structural and spectroscopic characterization of two new layered uranyl(VI) p-xylenediphosphonate compounds synthesized via ionothermal method

“…The crystal chemistry of actinide phosphonates is an important subfield of metal phosphonates, where major attention was paid to uranium [13][14][15][16][17][18][19] and thorium [20][21][22], with only a few neptunium [22][23][24], plutonium [25][26][27][28], and americium [28] complexes. Layered structure is always observed in uranyl phosphonates, due to the nature of equatorial coordination sites (from four to six) of the uranyl ion, leading the structure to 2D topologies [19,[29][30][31][32][33][34]. There are only several phosphonate ligands that were extensively studied to yield 1D, 2D and 3D structures, namely pxylenediphosphonic acid (pmbH 4 ) [35,36] Crystallographic Studies.…”

Structural chemistry of uranium phosphonates

“…Due to the characteristic coordination manner of the UO 2 2+ cation, the majority of reported homometallic uranyl phosphonoacetates is dominated by 2D structures [52][53][54][55][56][57]. As far as we know, only one 1D structure and one 3D structure have been reported using a carboxyphosphonate ligand, compared to twelve layered structures.…”

“…If the chains are joined by the remaining carboxylate O atom, then the layered structure of Na[(UO 2)(PPA)]·2H 2 O (NaUPAA-1) is formed [52]. A[(UO 2 )(PPA)]·nH 2 O (A = Na, Cs, NH 4 )[53][54][55] possesses a very similar layered arrangement to NaUPAA-1 in the sense that PPA chelates and bridges four uranyl centers. The only difference is the arrangement of the three PO 3 and two CO 2 moieties in the surrounding area of the unique uranium center.…”

Synthesis, Crystal Structure, and Characterization of Two Novel One- and Two-Dimensionally Polymeric Copper(II) Phosphonoacetates

“…Using bifunctional organophosphonates, e.g. diphosphonate or phosphonocarboxylate units as ligands, various structural motives can be made possible . Zinc 5‐phosphonobenzene‐1,3‐dicarboxylate can be used as catalyst in Friedel‐Crafts benzylation reactions and cobalt uranyl phosphonoacetate shows selective CO 2 uptake .…”