The study of the redox chemistry of mid-actinides (U–Pu) has historically relied on cerium as a model, due to the accessibility of trivalent and tetravalent oxidation states for these ions. Recently, dramatic shifts of lanthanide 4+/3+ non-aqueous redox couples have been established within a homoleptic imidophosphorane ligand framework. Herein we extend the chemistry of the imidophosphorane ligand (NPC=[N=PtBu(pyrr)2]–; pyrr=pyrrolidinyl) to tetrahomoleptic NPC complexes of neptunium and cerium (1-M, 2-M, M=Np, Ce) and present comparative structural, electrochemical, and theoretical studies of these complexes. Large cathodic shifts in the M4+/3+ (M=Ce, U, Np) couples underpin the stabilization of higher metal oxidation states owing to the strongly donating nature of the NPC ligands, providing access to the U5+/4+, U6+/5+, and to an unprecedented, well-behaved Np5+/4+ redox couple. Furthermore, the differences in the chemical redox properties of the U vs. Ce and Np complexes are rationalized based on their redox potentials, degree of structural rearrangement upon reduction/oxidation, relative molecular orbital energies, and orbital composition analyses employing density functional theory.
Otte, Kaitlyn S., Niklas, Julie E., Studvick, Chad M., Boggiano, Andrew C., Bacsa, John, Popov, Ivan A., & La Pierre, Henry S. (2023). Divergent Stabilities of Tetravalent Cerium, Uranium, and Neptunium Imidophosphorane Complexes. Angewandte Chemie (International Edition), 62(34). https://doi.org/10.1002/anie.202306580
Otte, Kaitlyn S., Niklas, Julie E., Studvick, Chad M., et al., "Divergent Stabilities of Tetravalent Cerium, Uranium, and Neptunium Imidophosphorane Complexes," Angewandte Chemie (International Edition) 62, no. 34 (2023), https://doi.org/10.1002/anie.202306580
@article{osti_2421235,
author = {Otte, Kaitlyn S. and Niklas, Julie E. and Studvick, Chad M. and Boggiano, Andrew C. and Bacsa, John and Popov, Ivan A. and La Pierre, Henry S.},
title = {Divergent Stabilities of Tetravalent Cerium, Uranium, and Neptunium Imidophosphorane Complexes},
annote = {The study of the redox chemistry of mid-actinides (U–Pu) has historically relied on cerium as a model, due to the accessibility of trivalent and tetravalent oxidation states for these ions. Recently, dramatic shifts of lanthanide 4+/3+ non-aqueous redox couples have been established within a homoleptic imidophosphorane ligand framework. Herein we extend the chemistry of the imidophosphorane ligand (NPC=[N=PtBu(pyrr)2]–; pyrr=pyrrolidinyl) to tetrahomoleptic NPC complexes of neptunium and cerium (1-M, 2-M, M=Np, Ce) and present comparative structural, electrochemical, and theoretical studies of these complexes. Large cathodic shifts in the M4+/3+ (M=Ce, U, Np) couples underpin the stabilization of higher metal oxidation states owing to the strongly donating nature of the NPC ligands, providing access to the U5+/4+, U6+/5+, and to an unprecedented, well-behaved Np5+/4+ redox couple. Furthermore, the differences in the chemical redox properties of the U vs. Ce and Np complexes are rationalized based on their redox potentials, degree of structural rearrangement upon reduction/oxidation, relative molecular orbital energies, and orbital composition analyses employing density functional theory.},
doi = {10.1002/anie.202306580},
url = {https://www.osti.gov/biblio/2421235},
journal = {Angewandte Chemie (International Edition)},
issn = {ISSN 1433-7851},
number = {34},
volume = {62},
place = {United States},
publisher = {Wiley},
year = {2023},
month = {06}}