Reduction of Np(<scp>vi</scp>) with hydrazinopropionitrile<i>via</i>water-mediated proton transfer

Li, Xiaobo; Wu, Qinghe; Wang, Congzhi; Lan, Jian‐Hui; Gibson, John K.; Chai, Zhifang

doi:10.1039/d2cp01730j

Cited by 5 publications

(9 citation statements)

References 79 publications

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“…We have theoretically examined the reaction mechanisms of Np(VI) by hydrazine, and its derivates, − and found that their reduction ability based on the theoretical energy barrier is consistent with the experimental results. , These results also confirm that the B3LYP/ECP60MWB/6-31G(d) level of theory used in our previous studies is suitable for the systems of Np(VI) reduction. In this work, we have further clarified the reduction mechanism of Np(VI) by carbohydrazide at the B3LYP/ECP60MWB/6-31G(d) level of theory.…”

Section: Introductionsupporting

confidence: 73%

“…It is noteworthy that the reaction from IC6 I to INT6 I needs a higher energy barrier (42.42 kcal mol –1 ) without the participation of water molecules, as shown in Figure S3. Previous studies have demonstrated that water-assisted H transfer can lower the reaction energy barrier. ,, Subsequently, INT6 I decomposes into IC7 I and two water molecules. IC7 I overcomes an energy barrier of 27.20 kcal mol –1 to obtain IC8 I and a N 2 molecule by intramolecular H transfer.…”

Section: Resultsmentioning

confidence: 97%

“…)] +• , which is similar to the result reported in previous work. 28 The Gibbs free energy change (ΔG) of eq 2 is −6.84 kcal mol −1 , reflecting that the process is also thermodynamically accessible.…”

Section: Resultsmentioning

confidence: 99%

“…Previous studies have demonstrated that waterassisted H transfer can lower the reaction energy barrier. 28,52,53 Subsequently, INT6 I decomposes into IC7 I and two water molecules. IC7 I overcomes an energy barrier of 27.20 kcal mol −1 to obtain IC8 I and a N 2 molecule by intramolecular H transfer.…”

Section: Resultsmentioning

confidence: 99%

“…A similar result is observed in the reduction of the fourth Np(VI), which is supported by previous work. 28 Therefore, the reduction of the first and third Np(VI) is the outer-sphere electron transfer, while that of the second and fourth Np(VI) is achieved by the hydrogen transfer. Based on the above results, in the first and third Np(VI) reduction, the spin state of Np in ICs, TSs, and INTs is a doublet electronic state.…”

Section: Resultsmentioning

confidence: 99%

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Insights into the Reduction Mechanisms of Np(VI) to Np(V) by Carbohydrazide

Wang

et al. 2023

J. Phys. Chem. A

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An efficient approach to Np separation in the Plutonium Uranium Reduction EXtraction (PUREX) process is to adjust Np(VI) to Np(V) by free-salt reductants, such as hydrazine and its derivatives. Recently, carbohydrazide (CO(N 2 H 3 ) 2 ), a derivative of hydrazine and urea, has received much attention, which can reduce Np(VI) to Np(V) in the extraction reprocessing of spent nuclear fuel. Herein, according to the experimental observations, we examine the reduction mechanism of four Np(VI) by one carbohydrazide molecule using multiple theoretical calculations. The fourth Np(VI) reduction with a 22.26 kcal mol −1 energy barrier is the rate-determining step, which is in accordance with the experimental observations (20.54 ± 1.20 kcal mol −1 ). The results of spin density reflect that the reduction of the first and third Np(VI) ion is an outer-sphere electron transfer, while that of the second and fourth Np(VI) ion is the hydrogen transfer. Localized molecular orbitals (LMOs) uncover that the breaking of the N−H bond and formation of the O yl −H bond are accompanied by the reaction from initial complexes (ICs) to intermediates (INTs). This work offers basic perspectives for the reduction mechanism of Np(VI) to Np(V) by CO(N 2 H 3 ) 2 , which is also expected to design excellent free-salt Np(VI) reductants for the separation of Np in the advanced PUREX process.

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