Do Perchlorate and Triflate Anions Bind to the Uranyl Cation in an Acidic Aqueous Medium? A Combined EXAFS and Quantum Mechanical Investigation

Comparative EXAFS Investigation of Uranium(VI) and -(IV) Aquo Chloro Complexes in Solution Using a Newly Developed Spectroelectrochemical Cell

“…The FT of the UO 2 2+ aquo ion (sample 0 M [Cl - ]) shows two peaks which arise from two O ax at 1.76 ± 0.02 Å and 5 equatorial oxygen atoms (O eq ) at 2.41 ± 0.02 Å. This result is in agreement with structural parameters obtained previously for the UO 2 2+ aquo ion in HClO 4 electrolyte. −

2 U L III -edge k 3 -weighted EXAFS data (left) and corresponding Fourier transforms (right) taken over k = 3.2−12.7 Å -1 for UO 2 2+ as a function of [Cl - ]: experimental data (line); theoretical curve fit (dots).

…”

Comparative EXAFS Investigation of Uranium(VI) and -(IV) Aquo Chloro Complexes in Solution Using a Newly Developed Spectroelectrochemical Cell

“…The FT of the UO 2 2+ aquo ion (sample 0 M [Cl - ]) shows two peaks which arise from two O ax at 1.76 ± 0.02 Å and 5 equatorial oxygen atoms (O eq ) at 2.41 ± 0.02 Å. This result is in agreement with structural parameters obtained previously for the UO 2 2+ aquo ion in HClO 4 electrolyte. −

2 U L III -edge k 3 -weighted EXAFS data (left) and corresponding Fourier transforms (right) taken over k = 3.2−12.7 Å -1 for UO 2 2+ as a function of [Cl - ]: experimental data (line); theoretical curve fit (dots).

…”

Force Field Development for Actinyl Ions via Quantum Mechanical Calculations: An Approach to Account for Many Body Solvation Effects

“…The position of the first peak in the RDF for the UU–OW interaction pair is at 2.44, 2.45, 2.41, and 2.41 Å for SPC/Fw, TIP3P, TIP4P, and TIP5P, respectively (see Figure ). These match well with the experimental estimates of 2.40–2.42 Å from extended X-ray absorption fine structure (EXAFS) ,,− and high energy X-ray scattering (HEXS) experiments. , From UU–OW number integrals in Figure , it is evident that, irrespective of the water models employed, there are five water molecules in the first equatorial solvation shell, which agrees well with other experiments. − ,− …”

“…Further analysis shows that the first shell splits into two layers above and below the equatorial plane, each containing four water molecules on the vertices of squares staggered by 45° (see Figure 1 in the Supporting Information). Although the position of the first peak agrees well with the experimental results, − the water coordination number in the first solvation is much higher than the experimentally reported value (∼5). − …”

Structure and Dynamics of Uranyl(VI) and Plutonyl(VI) Cations in Ionic Liquid/Water Mixtures via Molecular Dynamics Simulations

“…The An-O(H 2 O) peak positions for mixtures with a high water content are similar to the value of 0.246 nm reported for both uranyl and plutonyl modeled with this force field in SPC/E water . The results are also similar to other values for actinyl complexes in aqueous solution reported in other computational work, ,,− though slightly longer than the results of previous quantum mechanical calculations ,,,,, and the distances of 0.240–0.242 nm measured via various experimental techniques. − The An-O(Tf 2 N) peak position is slightly shorter than the previously reported value of 0.26 nm for uranyl in [BMIM][Tf 2 N] . This small difference is likely due to the use of different force fields for both the actinyl cation and IL.…”

Comparative EXAFS Investigation of Uranium(VI) and -(IV) Aquo Chloro Complexes in Solution Using a Newly Developed Spectroelectrochemical Cell

“…The FT of the UO 2 2+ aquo ion (sample 0 M [Cl - ]) shows two peaks which arise from two O ax at 1.76 ± 0.02 Å and 5 equatorial oxygen atoms (O eq ) at 2.41 ± 0.02 Å. This result is in agreement with structural parameters obtained previously for the UO 2 2+ aquo ion in HClO 4 electrolyte. −

2 U L III -edge k 3 -weighted EXAFS data (left) and corresponding Fourier transforms (right) taken over k = 3.2−12.7 Å -1 for UO 2 2+ as a function of [Cl - ]: experimental data (line); theoretical curve fit (dots).

…”

Force Field Development for Actinyl Ions via Quantum Mechanical Calculations: An Approach to Account for Many Body Solvation Effects

“…The position of the first peak in the RDF for the UU–OW interaction pair is at 2.44, 2.45, 2.41, and 2.41 Å for SPC/Fw, TIP3P, TIP4P, and TIP5P, respectively (see Figure ). These match well with the experimental estimates of 2.40–2.42 Å from extended X-ray absorption fine structure (EXAFS) ,,− and high energy X-ray scattering (HEXS) experiments. , From UU–OW number integrals in Figure , it is evident that, irrespective of the water models employed, there are five water molecules in the first equatorial solvation shell, which agrees well with other experiments. − ,− …”

“…Further analysis shows that the first shell splits into two layers above and below the equatorial plane, each containing four water molecules on the vertices of squares staggered by 45° (see Figure 1 in the Supporting Information). Although the position of the first peak agrees well with the experimental results, − the water coordination number in the first solvation is much higher than the experimentally reported value (∼5). − …”

Structure and Dynamics of Uranyl(VI) and Plutonyl(VI) Cations in Ionic Liquid/Water Mixtures via Molecular Dynamics Simulations

“…The An-O(H 2 O) peak positions for mixtures with a high water content are similar to the value of 0.246 nm reported for both uranyl and plutonyl modeled with this force field in SPC/E water . The results are also similar to other values for actinyl complexes in aqueous solution reported in other computational work, ,,− though slightly longer than the results of previous quantum mechanical calculations ,,,,, and the distances of 0.240–0.242 nm measured via various experimental techniques. − The An-O(Tf 2 N) peak position is slightly shorter than the previously reported value of 0.26 nm for uranyl in [BMIM][Tf 2 N] . This small difference is likely due to the use of different force fields for both the actinyl cation and IL.…”

Comparative EXAFS Investigation of Uranium(VI) and -(IV) Aquo Chloro Complexes in Solution Using a Newly Developed Spectroelectrochemical Cell

“…The FT of the UO 2 2+ aquo ion (sample 0 M [Cl - ]) shows two peaks which arise from two O ax at 1.76 ± 0.02 Å and 5 equatorial oxygen atoms (O eq ) at 2.41 ± 0.02 Å. This result is in agreement with structural parameters obtained previously for the UO 2 2+ aquo ion in HClO 4 electrolyte. −

2 U L III -edge k 3 -weighted EXAFS data (left) and corresponding Fourier transforms (right) taken over k = 3.2−12.7 Å -1 for UO 2 2+ as a function of [Cl - ]: experimental data (line); theoretical curve fit (dots).

…”

Force Field Development for Actinyl Ions via Quantum Mechanical Calculations: An Approach to Account for Many Body Solvation Effects

“…The position of the first peak in the RDF for the UU–OW interaction pair is at 2.44, 2.45, 2.41, and 2.41 Å for SPC/Fw, TIP3P, TIP4P, and TIP5P, respectively (see Figure ). These match well with the experimental estimates of 2.40–2.42 Å from extended X-ray absorption fine structure (EXAFS) ,,− and high energy X-ray scattering (HEXS) experiments. , From UU–OW number integrals in Figure , it is evident that, irrespective of the water models employed, there are five water molecules in the first equatorial solvation shell, which agrees well with other experiments. − ,− …”

“…Further analysis shows that the first shell splits into two layers above and below the equatorial plane, each containing four water molecules on the vertices of squares staggered by 45° (see Figure 1 in the Supporting Information). Although the position of the first peak agrees well with the experimental results, − the water coordination number in the first solvation is much higher than the experimentally reported value (∼5). − …”

Structure and Dynamics of Uranyl(VI) and Plutonyl(VI) Cations in Ionic Liquid/Water Mixtures via Molecular Dynamics Simulations

“…The An-O(H 2 O) peak positions for mixtures with a high water content are similar to the value of 0.246 nm reported for both uranyl and plutonyl modeled with this force field in SPC/E water . The results are also similar to other values for actinyl complexes in aqueous solution reported in other computational work, ,,− though slightly longer than the results of previous quantum mechanical calculations ,,,,, and the distances of 0.240–0.242 nm measured via various experimental techniques. − The An-O(Tf 2 N) peak position is slightly shorter than the previously reported value of 0.26 nm for uranyl in [BMIM][Tf 2 N] . This small difference is likely due to the use of different force fields for both the actinyl cation and IL.…”