Identification of the limiting species in the plutonium(IV) carbonate system. Solid state and solution molecular structure of the [Pu(CO){sub 3}{sub 5}]{sup 6{minus}} ion
- Los Alamos National Lab., NM (United States)
the identity of the limiting Pu(IV) species under high carbonate concentrations has been determined to be Pu(CO{sub 3}){sub 5}{sup 6{minus}}. Single crystals of [Na{sub 6}Pu(CO){sub 3}{sub 5}]{sub 2} {center_dot} Na{sub 2}CO{sub 3} {center_dot} 33H{sub 2}O were obtained from a 0.15 M solution of Pu(IV) in 2.6M Na{sub 2}CO{sub 3}. The asymmetric unit contains a complex network consisting of [Pu(CO{sub 3}){sub 5}]{sup 6{minus}} anions and Na{sup +} cations which are linked through interactions with CO{sub 3}{sup 2{minus}} and H{sub 2}O ligands. Each Na{sup +} ion is coordinated to the O atoms of H{sub 2}O or CO{sub 3}{sup 2{minus}} ligands such that the Na{sup +} ions achieve either octahedral or square-based pyramidal coordination. The [Pu(CO{sub 3}){sub 5}]{sup 6{minus}} anions can be viewed as a pseudohexagonal bipyramid with three CO{sub 3}{sup 2{minus}} ligands in a equatorial plane and two in axial positions. EXAFS data for Pu(IV) in 2.5M Na{sub 2}CO{sub 3} solution were collected at the Pu L{sub III} edge. Curve fitting reveals three shells in the FT spectrum. The UV-vis diffuse reflectance spectrum of a single crystal of [Na{sub 6}Pu(CO){sub 3}{sub 5}]{sub 2} {center_dot} Na{sub 2}CO{sub 3} {center_dot} 33H{sub 2}O ground into a powder is nearly identical to the solution absorption spectrum of the limiting Pu(IV) carbonato complex in 2.5 M Na{sub 2}CO{sub 3} solution. The peak by peak correspondence by position and relative absorption strengths, along with solution EXAFS data, suggest that the Pu(IV) chromophore is the same in both cases, and confirms that the [Pu(CO{sub 3}){sub 5}]{sup 6{minus}} ions is the limiting species in high carbonate solutions. Crystal data for [Na{sub 6}Pu(CO{sub 3}){sub 5}]{sub 2} {center_dot} Na{sub 2}CO{sub 3} {center_dot}-33H{sub 2}O are given.
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 642399
- Journal Information:
- Inorganic Chemistry, Vol. 37, Issue 12; Other Information: PBD: 15 Jun 1998
- Country of Publication:
- United States
- Language:
- English
Similar Records
Structural determination of Np(VII) compounds under alkaline conditions
Decontamination of carbonate containing process streams in nuclear fuel reprocessing by ion exchange chromatography