Molecular dynamics simulation study of lanthanide ions Ln{sup 3+} in aqueous solution. Analysis of the structure of the first hydration shell and of the origin of symmetry fluctuations
- Universite de Lausanne (Switzerland)
We have analyzed molecular dynamics simulations of tripositive lanthanide ions Ln{sup 3+} in aqueous solution. We were able to extract in detail their angular structure and their dynamic behavior along the series of Ln{sup 3+} ions. For a heavy lanthanide ion (Yb{sup 3+}) the eight water molecules of the first hydration shell form a well-defined square antiprism, whereas for a nine-coordinate light lanthanide ion (Nd{sup 3+}) the first hydration shell adopts the tricapped trigonal prism geometry. In the middle of the series both geometries coexist. Both the square antiprism and the tricapped trigonal prism rearrange via 90{degree} pseudorotations of the main symmetry axis. The pertaining transition state of lowered symmetry is a dodecahedron for the Yb{sup 3+} octaaqua complex and a capped square antiprism for the Nd{sup 3+} enneaaqua complex. The lifetime of a square antiprism between two pseudorotations is 11 ps but amounts to only 2 ps for a tricapped trigonal prism. The lifetime of a square antiprism from the simulation of Yb{sup 3+} (CN = 8) is in quantitative agreement with the correlation time for the fluctuation of the zero-field splitting from experimental EPR spectra of the Gd{sup 3+} octaaqua complex. On the basis of our MD-simulations we can go beyond these general notions and propose a model with 90{degree} pseudorotations of the coordination polyhedron as the principal mechanism for distortions of the first hydration shell. 26 refs., 11 figs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 105279
- Journal Information:
- Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 35 Vol. 99; ISSN JPCHAX; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
Similar Records
Synthesis and crystal structure of Ln[sub 3](OH)(CrO[sub 4])[sub 4] 3. 5H[sub 2]O (Ln = Pr, Nd) and Ln[sub 2](OH)[sub 2] (CrO[sub 4])[sub 2] (Ln = Tb, Gd): Thermal behavior and infrared spectra of Pr[sub 3](OH) (CrO[sub 4])[sub 4] 3. 5H[sub 2]O and Gd[sub 2](OH)[sub 2](CrO[sub 4])[sub 2]
Solvothermal syntheses, and characterization of [Ln(en){sub 4}(SbSe{sub 4})] (Ln=Ce, Pr) and [Ln(en){sub 4}]SbSe{sub 4}.0.5en (Ln=Eu, Gd, Er, Tm, Yb): The effect of lanthanide contraction on the crystal structures of lanthanide selenidoantimonates(V)