Carbon-13 NMR characterization of actinyl(VI) carbonate complexes in aqueous solution

Conference · Wed Jan 01 04:00:00 EST 1992

OSTI ID:5260638

Clark, D L; Hobart, D E; Palmer, P D ^[1]; Sullivan, J C ^[2]; Stout, B E ^[3]

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1. Los Alamos National Lab., NM (United States)
2. Argonne National Lab., IL (United States)
3. Cincinnati Univ., OH (United States). Dept. of Chemistry

The uranyl(VI) carbonate system has been re-examined using {sup 13}C NMR of 99.9% {sup 13}C-enriched U{sup VI}O{sub 2} ({sup 13}CO{sub 3}){sub 3}{sup 4{minus}} in millimolar concentrations. By careful control of carbonate ion concentration, we have confirmed the existence of the trimer, and observed dynamic equilibrium between the monomer and the timer. In addition, the ligand exchange reaction between free and coordinated carbonate on Pu{sup VI}O{sub 2}({sup 13}CO{sub 3}){sub 3}{sup 4{minus}} and Am{sup VI}O{sub 2}({sup 13}CO{sub 3}){sub 3}{sup 4{minus}} systems has been examined by variable temperature {sup 13}C NMR line-broadening techniques {sup 13}C NMR line-broadening techniques. A modified Carr-Purcell-Meiboom-Gill NMR pulse sequence was written to allow for experimental determination of ligand exchange parameters for paramagnetic actinide complexes. Preliminary Eyring analysis has provided activation parameters of {Delta}G{sup {double dagger}}{sub 295} = 56 kJ/M, {Delta}H{sup {double dagger}} = 38 kJ/M, and {Delta}S{sup {double dagger}} = {minus}60 J/M-K for the plutonyl triscarbonate system, suggesting an associative transition state for the plutonyl (VI) carbonate complex self-exchange reaction. Experiments for determination of the activation parameters for the americium (VI) carbonate system are in progress.

• Research Organization: Los Alamos National Lab., NM (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 5260638
• Report Number(s): LA-UR-92-1648; CONF-920625--5; ON: DE92015150
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ACTINIDE COMPOUNDS
AMERICIUM CARBONATES
AMERICIUM COMPOUNDS
AQUEOUS SOLUTIONS
CARBON 13
CARBON COMPOUNDS
CARBON ISOTOPES
CARBONATES
CHEMICAL REACTIONS
COMPLEXES
DISPERSIONS
EVEN-ODD NUCLEI
ISOMERS
ISOTOPES
LIGHT NUCLEI
MIXTURES
MOLECULAR STRUCTURE
NMR SPECTRA
NUCLEI
OXYGEN COMPOUNDS
PLUTONIUM CARBONATES
PLUTONIUM COMPOUNDS
SOLUTIONS
SPECTRA
STABLE ISOTOPES
THERMODYNAMICS
TRANSPLUTONIUM COMPOUNDS
TRANSURANIUM COMPOUNDS
URANIUM COMPOUNDS
URANYL CARBONATES
URANYL COMPOUNDS