Binding of pertechnetate to uranyl(VI) in aqueous solution. A density functional theory molecular dynamics study

Inorganic Chemistry

Volumn 46, Issue 20, 2007, Pages 8129-8131

  Buhl, Michael ^a   Golubnychiy, Volodymyr ^a  

^a MAX PLANCK INSTITUT FÜR KOHLENFORSCHUNG   (Germany)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 35348925992     PISSN: 00201669     EISSN: None     Source Type: Journal    
DOI: 10.1021/ic701431u     Document Type: Article

References (26)

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5. Car, R.; Parrinello, M. Phys. Rev. Lett. 1985, 55, 2471.
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7. (a) Bühl, M.; Diss, R.; Wipff, G. J. Am. Chem. Soc. 2005, 127, 13506.
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10. (d) Bühl, M.; Kabrede, H. ChemPhysChem 2006, 7, 2290.
11. (e) Bühl, M.; Diss, R.; Wipff, G. Inorg. Chem. 2007, 46, 5196.
12. CPMD simulations were performed with the CPMD program (CPMD. version 3.9.2; copyright by IBM Corp. and Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany), the gradient-corrected BLYP functional (Becke, A. D. Phys. Rev. A 1988, 38, 3098;
13. Lee, C.; Yang, W.; Parr, R. G. Phys. Rev. B 1988, 37, 785),
14. and norm-conserving Troullier-Martins pseudopotentials (Troullier, N.; Martins, J. L. Phys. Rev. B 1991, 43, 1993;
15. Kleinman, L.; Bylander, D. M. Phys. Rev. Lett. 1982, 48, 1425); see ref 6a and the Supporting Information for further details concerning construction and validation of the pseudopotentials for uranium and technetium, respectively.
16. -. Kohn-Sham orbitals were expanded in plane waves up to an energy cutoff of 80 Ry. Molecular dynamics (MD) simulations were run in the NVT ensemble using a single Nosé-Hoover thermostat set to 320 K (in order to increase the mobility of the liquid, which tends to be too sluggish at 300 K with most generalized gradient approximations, see: VandeVondele, J.; Mohamed, F.; Krack, M.; Hutter, J.; Sprik, M.; Parrinello, M. J. Chem. Phys. 2005, 122, 014515), a fictitious electronic mass of 600 au, and a time step of 0.121 fs. To maintain this time step, H was substituted with D.
17. 4, respectively, at the BLYP/LANL2DZ(U)/SDD/(Tc)/6-31G** level. There is thus no evidence for a chelating propensity of pertechnetate.
18. -4 au or less, similar to the degree of convergence documented in Figure S1 of the Supporting Information of ref 6a. The standard deviations from each point were used to estimate upper and lower limits for the integral of the (numeric) thermodynamic integration. Each new point was continued from the final, equilibrated configuration of the previous one, using 2000 steps of continuous slow growth to increase the constrained distance.
19. We discuss relative energies of selected points on a free-energy surface rather than reaction mechanisms. Such energies are, at least in principle, independent of the chosen path. The actual displacement reaction (eq 3) may well follow an associative mechanism, as in the case of water exchange at uranyl (cf. ref 6c and literature cited therein).
20. +. See: Grenthe, I.; Fuger, J.; Konings, R. J. M.; Lemire, R. J.; Muller, A. B.; Nguyen-Trung, C.; Wanner, H. In Chemical Thermodynamics Vol. 1: Chemical Thermodynamics of Uranium; Wanner, H., Forest, I., Eds.; Elsevier: Amsterdam, The Netherlands, 1992.
21. For instance, see: Morel, F. M. M.; Hering, J. G. Principles and Applications of Aquatic Chemistry; John Wiley & Sons: New York, 1993; p 399, where a simple expression from statistical considerations of electrostatic interactions between ions in a dielectric continuum was used for this estimate. In principle, but evidently not in practice, this process could be modeled by prolonging the path in Figure 1 to infinity.
22. Because volume changes are very small in the condensed phase, ΔG and ΔA should be very similar.
23. For classical MD simulations of uranyl extraction, see, e.g.: Baaden, M.; Schurhammer, R.; Wipff, G. J. Phys. Chem. B 2002, 106, 434.
24. Computed at the BLYP/LANL2DZ(U)/SDD(Tc)/6-31G** level using Gaussian 03; see the Supporting Information for details. PCM single-point computations employed the parameters of water.
25. (a) Suresh, C. H.; Koga, N. Inorg. Chem. 2002, 41, 1573.
26. (b) Review: Kühl, O. Coord. Chem. Rev. 2005, 249, 693.