Electron transfer in uranyl(VI)-uranyl(V) complexes in solution
2004 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 126, no 31, 9801-9808 p.Article in journal (Refereed) Published
The rates and mechanisms of the electron self-exchange between U(V) and U(VI) in solution have been studied with quantum chemical methods. Both outer-sphere and inner-sphere mechanisms have been investigated; the former for the aqua ions, the latter for binuclear complexes containing hydroxide, fluoride, and carbonate as bridging ligand. The calculated rate constant for the self-exchange reaction UO2+(aq) + UO22+(aq)UO22+(aq) + UO2+(aq), at 25 degreesC, is k = 26 M-1 s(-1). The lower limit of the rate of electron transfer in the inner-sphere complexes is estimated to be in the range 2 x 10(4) to 4 x 10(6) M-1 s(-1), indicating that the rate for the overall exchange reaction may be determined by the rate of formation and dissociation of the binuclear complex. The activation energy for the outer-sphere model calculated from the Marcus model is nearly the same as that obtained by a direct calculation of the precursor- and transition-state energy. A simple model with one water ligand is shown to recover 60% of the reorganization energy. This finding is important because it indicates the possibility to carry out theoretical studies of electron-transfer reactions involving M3+ and M4+ actinide species that have eight or nine water ligands in the first coordination sphere.
Place, publisher, year, edition, pages
2004. Vol. 126, no 31, 9801-9808 p.
energy-adjusted pseudopotentials, spin-orbit method, ab-initio, mean-field, exchange reaction, aqueous-solution, gas-phase, thermodynamics, ions, chemistry
IdentifiersURN: urn:nbn:se:kth:diva-23627DOI: 10.1021/ja049205oISI: 000223110100073ScopusID: 2-s2.0-3843061132OAI: oai:DiVA.org:kth-23627DiVA: diva2:342326
QC 20100525 QC 201109272010-08-102010-08-102011-09-27Bibliographically approved