Notes. First synthesis and structural assessment of alkali-metal carbonatodioxoperoxouranate(VI) monohydrates, A₂[UO₂(O₂)(CO₃)]·H₂O, and carbonato-oxodiperoxovanadate(V) trihydrates, A₃[VO(O₂)₂(CO₃)]·3H₂O

Abstract

The complexes 4[ UO,( 0,) (CO,)]*H,O (A = Na or K) have been synthesised from the reaction of the product obtained by treating UO,( N0,),*6H20 with AOH and AHCO, (ratio U : Cot-= 1 : 4) with an excess of 30% H,O, at pH 7-8, and A,[VO(0,),(C0,)]~3H20 (A = Na or K) have been synthesised by treating V, O, with A,CO, (ratio V: C o t -= 1 : 1.5) and an excess of 30% H, O, at pH ca. 7. They were precipitated with ethanol. The occurrence of trans O=U=O and terminal V=O in the [UO,(O,) (CO3)I2and [VO(02)2(C03)]3ions, respectively, and the presence of triangular bidentate OZ2and chelated bidentate C o tgroups, have been ascertained from i.r. and laser Raman spectra. The complexes A,[UO,(O,) (CO,) ]-H,O can be dehydrated at ca. 100 "C, a temperature at which A3[VO(02),(C03)]~3H20 starts to decompose.

Kinetic Study of the Oxidative Dissolution of UO2 in Aqueous Carbonate Media

“…Single-crystal X-ray analysis of a precipitate formed from a uranyl(VI) peroxocarbonate solution identified a molecular mononuclear U(VI) structure, K 4 UO 2 (O 2 )(CO 3 ) 2 , with the peroxide and carbonate ligands bidentately coordinated in the equatorial plane to the U(VI) metal center . Similar binding geometries have been reported for another uranium(VI) peroxocarbonate compound, as well as for lanthanide peroxocarbonates. , These structural data, in conjunction with the data shown in Figure B, suggest that the solution species present 4 h after dissolution has the composition UO 2 (O 2 )(CO 3 ) 2 4- .…”

Syntheses, Structural Characterization, Reactivity, and Theoretical Studies on Some Heteroligand Oxoperoxotungstate(VI)

“…The complex was isolated as the potassium salt. The importance of the pH for the successful synthesis of peroxo metal compounds has been emphasized in the literature . For the successful synthesis of oxoperoxotungsten complex containing carbonate (CO 3 2− ) as the ancillary ligand, pH > 7 was considered conducive in order to prevent the reaction CO 3 2− + 2H + → CO 2 + H 2 O.…”