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Updated: Jan 18, 2026

The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes
Published on: April 10, 2015
Solvation Structure of 237Np4+ in a Noncomplexing Environment
Daria V Boglaienko1, Amity Andersen1, John L Fulton1
1Pacific Northwest National Laboratory, Richland, Washington 99352, United States.
None:
The solvation structure of an Np4+ ion in an aqueous, noncomplexing and nonoxidizing environment of trifluoromethanesulfonic (triflic) acid was investigated with X-ray absorption spectroscopy (XAS) combined with ab initio molecular dynamics (AIMD) and time-dependent density functional theory (TDDFT) calculations. Np LIII-edge X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) data were collected for Np4+ in 1, 3, and 7 M triflic acid using a laboratory-scale spectrometer and separately at a synchrotron facility, producing data sets in excellent agreement. TDDFT calculations revealed a weak pre-edge feature not previously reported for Np LIII-edge XANES. AIMD modeling results showed differences in the hydration shell of the Np4+ ion at different concentrations of triflic acid; these results are supported by the experiment. EXAFS fit models to the experiment resulted in similar coordination of Np4+ in noncomplexing aqueous media as reported in the literature for 1 M perchloric acid but, together with calculations, revealed more than one distance between Np and O atoms in 7 M triflic acid. These results imply monodentate coordination with sulfonate groups in 7 M triflic acid and suggest the possibility of proto-neptunyl species in relatively low-concentration Np4+ acid solutions.
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