PNNL

Abstract

The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. The rates of a wide variety of reactions in aqueous coordination compounds can be correlated with lifetimes of water molecules in the inner-coordination shell of the metal. For simple octahedral metal ions, these lifetimes span ~10²° but are unknown, and experimentally inaccessible, for reactive sites in interfacial environments. Using recent data on nanometer-sized aqueous aluminum clusters, we show that lifetimes can be calculated from reactiveflux molecular dynamics simulations. Rates scale with the calculated metal-water bond lengths. Surprisingly, on all aluminum(III) mineral surface sites investigated, waters have lifetimes in the range of 10?8-10?power10 s, making the surface sites as fast as the most reactive ions in the solution.