(LLNL), Livermore, CA (United States) Energy Frontier Research Centers (EFRC) (United States). Publication Date: Research Org.: Lawrence Livermore National Lab. of California, Davis, CA (United States).

Finally, at pH8.0 there is almost no dependence on temperature, which is interpreted to indicate that hydrolysis is coupled to ligand exchange under these conditions. Variable-temperature NMR spectroscopy was also performed to measure activation parameters of complexation. A set of experiments were conducted in which pH and total oxalate concentration were varied, and the linear dependence of the rate on these parameters was demonstrated. Because the neptunium(V) complex is paramagnetic, the rates of ligand exchange were estimated by following the width of the 13C and 17O signals assigned to the free oxalate ion in solution and by applying the Swift–Connick method for measuring rates of exchange. Rates of exchange were measured in the pH regime of 6.5–9.0, at which speciation is shown to be suitably simple. The kinetics of ligand exchange between the free oxalate ion, C 2O 4 2-, and the bis-oxalato Np V complex, 3-, in aqueous solution are reported by using 13C and 17O NMR spectroscopy methods.

Mestrenova half peak width