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MO: Molekülphysik
MO 5: Cluster II: Atomare Cluster (gemeinsam mit FV Atomphysik)
MO 5.5: Vortrag
Dienstag, 5. März 2002, 15:00–15:15, HS 01/E01
Salt-Bridge Transition States for Charge Separation in Hydrated, Doubly Charged Metal Ions — •Martin K. Beyer — Institut für Physikalische und Theoretische Chemie, TU München, Lichtenbergstraße 4, 85747 Garching
Doubly charged hydrated metal ions can undergo a charge separation of the form M2+(H2O)n → MOH+(H2O)n−2 + H3O+. For n=2 it was shown by DFT calculations [1] that a salt-bridge transition state determines the barrier height of the lowest energy pathway for alkaline earth metal dications. Here, the influence of additional solvent molecules on the potential energy surface of the reaction is discussed with Co2+(H2O)n, n=2−4. In each case, a water molecule is first promoted from the first to the second solvation shell. Proton transfer takes place along a hydrogen bond between two water molecules of the first and second solvation shell. In the respective transition state, charge is arranged in a M2+−OH−−H3O+ salt-bridge. The computational results for n=4 compare favourably with the recent experimental measurement by Metz and coworkers [2], who determined the kinetic energy release due to Coulomb explosion after photoexcitation at 570 nm.
[1] M. Beyer, E. R. Williams, and V. E. Bondybey, J. Am. Chem. Soc. 121, 1565-1573 (1999).
[2] K. P. Faherty, C. J. Thompson, F. Aguiree, J. Michne, and R. B. Metz, J. Phys. Chem. A 105, 10054-10059 (2001).