Rubidium uranyl phosphates and arsenates with polymeric tetrahedral anions: Syntheses and structures of Rb4[(UO2)6(P2O7)4(H2O)], Rb2[(UO2)3(P2O7)(P4O12)] and Rb[(UO2)2(As3O10)]

The three new framework Rb uranyl phosphates and arsenates with anionic parts based on different type of polymeric anions have been prepared by high-temperature solid-state reactions: Rb4[(UO2)6(P2O7)4(H2O)] (1), Rb2[(UO2)3(P2O7)(P4O12)] (2), Rb[(UO2)2(As3O10)] (3). The crystal structures of the synthesized compounds have been solved by direct methods: 1—monoclinic P21/c, a=9.672(1) Å, b=12.951(1) Å, c=32.231(3) Å, β=90.116(4)°, V=4037.3(6) Å3, Z=4, R1=0.0926 for 6351 unique reflections with |F0|≥4σF|F0|≥4σF; 2—monoclinic, P21/c, a=6.791(1) Å, b=16.155(3) Å, c=19.856(4) Å, β=97.48(5)°, V=2159.8(7) Å3, Z=4, R1=0.0286 for 3617 unique reflections with |F0|≥4σF|F0|≥4σF; 3—orthorhombic, Pbcn, a=10.558(1) Å, b=11.037(1) Å, c=11.464(1) Å, V=1335.9(2) Å3, Z=4, R1=0.0489 for 1384 unique reflections with |F0|≥4σF|F0|≥4σF. The structures of title are compounds based on 3D negatively charged frameworks with chemical compositions [(UO2)6(P2O7)4(H2O)]4− in 1, [(UO2)3(P2O7)(P4O12)]2− in 2 and [(UO2)2(As3O10)]− in 3. These negative charges are compensated by rubidium cations which are in the channels of 1 and closed cages in structures of 2 and 3. The channels in 1 are directed along the a direction and have minimum dimensions ∼5 Å×6 Å. This is the first example of porosity generation through solid state synthesis in uranyl compounds. For the first time in uranium chemistry polymeric anionic groups P4O12 and As3O10 were observed in structure of 2 and 3.

The polyhedral (a) and topological (b) representation of the Rb4[(UO2)6(P2O7)4(H2O)] crystal structure.Figure optionsDownload as PowerPoint slide