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Density functional theory study of uranium(VI) aquo chloro complexes in aqueous solution
Michael Bühl1, Nicolas Sieffert, Volodymyr Golubnychiy
1Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany. buehl@st-andrews.ac.uk
The Journal of Physical Chemistry. A
|February 14, 2008
Summary
Computational studies reveal that solvent significantly impacts uranyl aquo chloro complexes. Uranyl coordination shifts from five to four at two or three chloride ligands, impacting its chemical behavior.
Area of Science:
- Inorganic Chemistry
- Computational Chemistry
- Physical Chemistry
Background:
- Uranyl (UO2^2+) forms mixed aquo chloro complexes in aqueous solutions.
- Understanding the coordination chemistry of uranyl is crucial for environmental and nuclear applications.
Purpose of the Study:
- To investigate the structural and energetic properties of mixed uranyl aquo chloro complexes.
- To determine the influence of solvent effects on uranyl coordination.
- To identify the chloride concentration at which uranyl coordination changes.
Main Methods:
- Density functional theory (DFT) calculations (BLYP, BP86, B3LYP) were employed for optimization.
- Polarizable continuum model (PCM) simulated bulk water effects.
- Car-Parrinello molecular dynamics (MD) simulations studied gas and aqueous phases.
- Free binding energies were calculated using static PCM and constrained MD simulations.
Main Results:
- Significant solvent effects were observed on geometric and energetic parameters of uranyl complexes.
- Comparison with EXAFS data suggests a coordination transition.
- The transition from five- to four-coordination occurs at y=2 or y=3 chloride ligands.
Conclusions:
- Solvent plays a critical role in the speciation of uranyl aquo chloro complexes.
- The coordination number of uranyl is sensitive to chloride concentration in aqueous solutions.
- These findings aid in predicting uranyl behavior in different chemical environments.
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