Proton-Coupled Electron Transfer at the Pu5+/4+ Couple

Kaitlyn S. Otte; Julie E. Niklas; Chad M. Studvick; Charlotte L. Montgomery; Alexandria R.C. Bredar; Ivan A. Popov; Henry S. La Pierre

doi:10.1021/jacs.4c06319

Proton-Coupled Electron Transfer at the Pu^5+/4+ Couple

Kaitlyn S. Otte
, Julie E. Niklas
, Chad M. Studvick
, Charlotte L. Montgomery
, Alexandria R.C. Bredar
, Ivan A. Popov
, Henry S. La Pierre

Research output: Contribution to journal › Article › peer-review

7 Scopus citations

Abstract

The synthesis and solution and solid-state characterization of [Pu⁴⁺(NPC)₄], 1-Pu, (NPC = [NP^tBu(pyrr)₂]⁻; ^tBu = C(CH₃)₃; pyrr = pyrrolidinyl) and [Pu³⁺(NPC)₄][K(2.2.2.-cryptand)], 2-Pu, is described. Cyclic voltammetry studies of 1-Pu reveal a quasi-reversible Pu^4+/3+ couple, an irreversible Pu^5+/4+ couple, and a third couple evincing a rapid proton-coupled electron transfer (PCET) reaction occurring after the electrochemical formation of Pu⁵⁺. The chemical identity of the product of the PCET reaction was confirmed by independent chemical synthesis to be [Pu⁴⁺(NPC)₃(HNPC)][B(ArF₅)₄], 3-Pu, (B(ArF₅)₄ = tetrakis(2,3,4,5,6-pentafluourophenyl)borate) via two mechanistically distinct transformations of 1-Pu: protonation and oxidation. The kinetics and thermodynamics of this PCET reaction are determined via electrochemical analysis, simulation, and density functional theory. The computational studies demonstrate a direct correlation between the changing nature of 5f and 6d orbital participation in metal-ligand bonding and the electron density on the N_im atom with the thermodynamics of the PCET reaction from Np to Pu, and an indirect correlation with the roughly 5-orders of magnitude faster Pu PCET compared to Np for the An⁵⁺ species.

Original language	English
Pages (from-to)	21859-21867
Number of pages	9
Journal	Journal of the American Chemical Society
Volume	146
Issue number	31
DOIs	https://doi.org/10.1021/jacs.4c06319
State	Published - Aug 7 2024
Externally published	Yes

Funding

We thank Jillian L. Dempsey (UNC) for insightful feedback on the electrochemical and kinetic analyses. We also acknowledge John Bacsa (GT) for his support in generating models that were used in the SC-XRD processing. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Heavy Element Chemistry program under Award Number DE-SC0019385 (K.S.O., J.E.N., H.S.L.). Computational work was conducted using the computational resources at the Ohio Supercomputer Center and the ARCC HPC cluster at the University of Akron. C.M.S. and I.A.P. are supported by the National Nuclear Security Administration’s (NNSA) grant DE-NA0004151. A.R.C.B. acknowledges the Arnold & Mabel Beckman Foundation for a postdoctoral fellowship.

Access to Document

10.1021/jacs.4c06319

Cite this

@article{dca6a543026243a28999253b86af7ce0,

title = "Proton-Coupled Electron Transfer at the Pu5+/4+ Couple",

abstract = "The synthesis and solution and solid-state characterization of [Pu4+(NPC)4], 1-Pu, (NPC = [NPtBu(pyrr)2]−; tBu = C(CH3)3; pyrr = pyrrolidinyl) and [Pu3+(NPC)4][K(2.2.2.-cryptand)], 2-Pu, is described. Cyclic voltammetry studies of 1-Pu reveal a quasi-reversible Pu4+/3+ couple, an irreversible Pu5+/4+ couple, and a third couple evincing a rapid proton-coupled electron transfer (PCET) reaction occurring after the electrochemical formation of Pu5+. The chemical identity of the product of the PCET reaction was confirmed by independent chemical synthesis to be [Pu4+(NPC)3(HNPC)][B(ArF5)4], 3-Pu, (B(ArF5)4 = tetrakis(2,3,4,5,6-pentafluourophenyl)borate) via two mechanistically distinct transformations of 1-Pu: protonation and oxidation. The kinetics and thermodynamics of this PCET reaction are determined via electrochemical analysis, simulation, and density functional theory. The computational studies demonstrate a direct correlation between the changing nature of 5f and 6d orbital participation in metal-ligand bonding and the electron density on the Nim atom with the thermodynamics of the PCET reaction from Np to Pu, and an indirect correlation with the roughly 5-orders of magnitude faster Pu PCET compared to Np for the An5+ species.",

author = "Otte, \{Kaitlyn S.\} and Niklas, \{Julie E.\} and Studvick, \{Chad M.\} and Montgomery, \{Charlotte L.\} and Bredar, \{Alexandria R.C.\} and Popov, \{Ivan A.\} and \{La Pierre\}, \{Henry S.\}",

note = "Publisher Copyright: {\textcopyright} 2024 The Authors. Published by American Chemical Society.",

year = "2024",

month = aug,

day = "7",

doi = "10.1021/jacs.4c06319",

language = "English",

volume = "146",

pages = "21859--21867",

journal = "Journal of the American Chemical Society",

issn = "0002-7863",

publisher = "American Chemical Society",

number = "31",

}

TY - JOUR

T1 - Proton-Coupled Electron Transfer at the Pu5+/4+ Couple

AU - Otte, Kaitlyn S.

AU - Niklas, Julie E.

AU - Studvick, Chad M.

AU - Montgomery, Charlotte L.

AU - Bredar, Alexandria R.C.

AU - Popov, Ivan A.

AU - La Pierre, Henry S.

PY - 2024/8/7

Y1 - 2024/8/7

N2 - The synthesis and solution and solid-state characterization of [Pu4+(NPC)4], 1-Pu, (NPC = [NPtBu(pyrr)2]−; tBu = C(CH3)3; pyrr = pyrrolidinyl) and [Pu3+(NPC)4][K(2.2.2.-cryptand)], 2-Pu, is described. Cyclic voltammetry studies of 1-Pu reveal a quasi-reversible Pu4+/3+ couple, an irreversible Pu5+/4+ couple, and a third couple evincing a rapid proton-coupled electron transfer (PCET) reaction occurring after the electrochemical formation of Pu5+. The chemical identity of the product of the PCET reaction was confirmed by independent chemical synthesis to be [Pu4+(NPC)3(HNPC)][B(ArF5)4], 3-Pu, (B(ArF5)4 = tetrakis(2,3,4,5,6-pentafluourophenyl)borate) via two mechanistically distinct transformations of 1-Pu: protonation and oxidation. The kinetics and thermodynamics of this PCET reaction are determined via electrochemical analysis, simulation, and density functional theory. The computational studies demonstrate a direct correlation between the changing nature of 5f and 6d orbital participation in metal-ligand bonding and the electron density on the Nim atom with the thermodynamics of the PCET reaction from Np to Pu, and an indirect correlation with the roughly 5-orders of magnitude faster Pu PCET compared to Np for the An5+ species.

AB - The synthesis and solution and solid-state characterization of [Pu4+(NPC)4], 1-Pu, (NPC = [NPtBu(pyrr)2]−; tBu = C(CH3)3; pyrr = pyrrolidinyl) and [Pu3+(NPC)4][K(2.2.2.-cryptand)], 2-Pu, is described. Cyclic voltammetry studies of 1-Pu reveal a quasi-reversible Pu4+/3+ couple, an irreversible Pu5+/4+ couple, and a third couple evincing a rapid proton-coupled electron transfer (PCET) reaction occurring after the electrochemical formation of Pu5+. The chemical identity of the product of the PCET reaction was confirmed by independent chemical synthesis to be [Pu4+(NPC)3(HNPC)][B(ArF5)4], 3-Pu, (B(ArF5)4 = tetrakis(2,3,4,5,6-pentafluourophenyl)borate) via two mechanistically distinct transformations of 1-Pu: protonation and oxidation. The kinetics and thermodynamics of this PCET reaction are determined via electrochemical analysis, simulation, and density functional theory. The computational studies demonstrate a direct correlation between the changing nature of 5f and 6d orbital participation in metal-ligand bonding and the electron density on the Nim atom with the thermodynamics of the PCET reaction from Np to Pu, and an indirect correlation with the roughly 5-orders of magnitude faster Pu PCET compared to Np for the An5+ species.

UR - https://www.scopus.com/pages/publications/85199525611

U2 - 10.1021/jacs.4c06319

DO - 10.1021/jacs.4c06319

M3 - Article

C2 - 39051969

AN - SCOPUS:85199525611

SN - 0002-7863

VL - 146

SP - 21859

EP - 21867

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

IS - 31

ER -

Proton-Coupled Electron Transfer at the Pu^5+/4+ Couple

Abstract

Funding

Access to Document

Other files and links

Fingerprint

Cite this