Directing Generation of Polynuclear Plutonium Species with Reduction and Protonation
5 affiliations
- 1Chemical Sciences and Engineering Division
- 2Argonne National Laboratory
- 3Department of Chemistry
- 4University of Kansas
- 5State University of New York at Buffalo
Abstract
Formation of multinuclear complexes is a defining feature of plutonium chemistry, but such reactivity tends to be uncontrolled under most conditions, hindering selective transformation of compounds containing this challenging element.Here, the chemistry leading to formation of two multinuclear complexes of plutonium coordinated by a chelating, dianionic ligand (denoted L N M ) has been studied.The complexes are generated on-demand via reduction and proton-assisted condensation of a mononuclear plutonyl(VI) complex.One complex contains two plutonium(IV) centers bridged by a central µ 2 -oxo and each capped with κ 2 -acetate ligands.The other complex contains the same [Pu IV2 O] core but is instead capped by anionic [Pu V O 2 L N M ] -fragments, thus constituting a linear tetrameric motif of the form [PuOL N M (µ 2 -O)PuL N M ] 2 (µ 2 -O).The capping interactions can be viewed through the lens of Sullivan-type "cation-cation" interactions between the Lewis-basic oxo moieties of the [Pu V O 2 L N M ] -species and Lewis-acidic Pu IV centers.Although such cation-cation interactions are generally favored by pentavalent actinyls, direct binding of [Pu V O 2 ] to [Pu IV ] has not been observed in prior work; this motif has been characterized here with Raman spectroscopy and Xray diffraction analysis.Electroanalytical, spectroscopic, and H/D kinetic isotope effect (KIE) data support a mechanism leading to the polynuclear species that involves sequential reduction, proton transfer, and condensation.As [AnO oxo -H] species are likely intermediates in the observed reactivity, experimentally measured reduction potentials and computationally predicted pK a values have been used to compute [AnO oxo -H] bond dissociation free energies (BDFEs) across the U, Np, Pu series.The results, considered in the broader context of proton-coupled electron transfer (PCET) chemistry, suggest that actinyl-derived hydroxide complexes could be potent H-atom donors and thus could be used to direct new types of reactivity.
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BibTeX
@misc{mikeska2026directing,
title = {{Directing Generation of Polynuclear Plutonium Species with Reduction and Protonation}},
author = {Emily Mikeska and Davis Curry and Richard Wilson and Asmita Sen and Jochen Autschbach and James Blakemore},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15010345/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010345/v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Directing Generation of Polynuclear Plutonium Species with Reduction and Protonation
AU - Emily Mikeska
AU - Davis Curry
AU - Richard Wilson
AU - Asmita Sen
AU - Jochen Autschbach
AU - James Blakemore
PY - 2026
DA - 2026/10/13
PB - ChemRxiv
DO - 10.26434/chemrxiv.15010345/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010345/v1
AB - Formation of multinuclear complexes is a defining feature of plutonium chemistry, but such reactivity tends to be uncontrolled under most conditions, hindering selective transformation of compounds containing this challenging element.Here, the chemistry leading to formation of two multinuclear complexes of plutonium coordinated by a chelating, dianionic ligand (denoted L N M ) has been studied.The complexes are generated on-demand via reduction and proton-assisted condensation of a mononuclear plutonyl(VI) complex.One complex contains two plutonium(IV) centers bridged by a central µ 2 -oxo and each capped with κ 2 -acetate ligands.The other complex contains the same [Pu IV2 O] core but is instead capped by anionic [Pu V O 2 L N M ] -fragments, thus constituting a linear tetrameric motif of the form [PuOL N M (µ 2 -O)PuL N M ] 2 (µ 2 -O).The capping interactions can be viewed through the lens of Sullivan-type "cation-cation" interactions between the Lewis-basic oxo moieties of the [Pu V O 2 L N M ] -species and Lewis-acidic Pu IV centers.Although such cation-cation interactions are generally favored by pentavalent actinyls, direct binding of [Pu V O 2 ] to [Pu IV ] has not been observed in prior work; this motif has been characterized here with Raman spectroscopy and Xray diffraction analysis.Electroanalytical, spectroscopic, and H/D kinetic isotope effect (KIE) data support a mechanism leading to the polynuclear species that involves sequential reduction, proton transfer, and condensation.As [AnO oxo -H] species are likely intermediates in the observed reactivity, experimentally measured reduction potentials and computationally predicted pK a values have been used to compute [AnO oxo -H] bond dissociation free energies (BDFEs) across the U, Np, Pu series.The results, considered in the broader context of proton-coupled electron transfer (PCET) chemistry, suggest that actinyl-derived hydroxide complexes could be potent H-atom donors and thus could be used to direct new types of reactivity.
ER -