Structure and Bonding Investigation of Plutonium Peroxocarbonate Complexes Using Cerium Surrogates and Electronic Structure Modeling

Abstract

Herein, we report the synthesis and structural characterization of K[(CO)Pu](μ-η-η-O)·12HO. This is the second Pu-containing addition to the previously studied alkali-metal peroxocarbonate series M[(CO)A](μ-η-η-O)·xHO (M = alkali metal; A = Ce or Pu; x = 8, 10, 12, or 18), for which only the M = Na analogue has been previously reported when A = Pu. The previously reported crystal structure for Na[(CO)Pu](μ-η-η-O)·12HO is not isomorphous with its known Ce analogue. However, a new synthetic route to these M[(CO)A](μ-η-η-O)·12HO complexes, described below, has produced crystals of Na[(CO)Ce](μ-η-η-O)·12HO that are isomorphous with the previously reported Pu analogue. Via this synthetic method, the M = Na, K, Rb, and Cs salts of M[(CO)Ce](μ-η-η-O)·xHO have also been synthesized for a systematic structural comparison with each other and the available Pu analogues using single-crystal X-ray diffraction, Raman spectroscopy, and density functional theory calculations. The Ce salts, in particular, demonstrate subtle differences in the peroxide bond lengths, which correlate with Raman shifts for the peroxide O-O stretch (O = O atoms of the peroxide bridges) with each of the cations studied: Na [1.492(3) Å/847 cm], Rb [1.471(1) Å/854 cm], Cs [1.474(1) Å/859 cm], and K [1.468(6) Å/870 cm]. The trends observed in the O-O bond distances appear to relate to supermolecular interactions between the neighboring cations.

Deciphering the Crystal Structure of a Scarce 1D Polymeric Thorium Peroxo Sulfate

“…Particularly, the band located at 859 cm −1 on the Raman spectrum (Figure ) and the very weak one observed at 818 cm −1 on FTIR spectrum (Figure S1) are assigned to the ν (O−O) symmetric stretching vibration mode of the peroxide ligand, in accordance with the bridging μ‐η 2 :η 2 coordination mode already observed for cerium(IV), uranium(VI) and plutonium(IV) compounds . The shift of the Raman band to lower wavenumber in comparison to free H 2 O 2 (around 880 cm −1 ) can be attributed to the coordinating Th IV cation . Raman bands positioned at 1128 and 1088 cm −1 ( ν 3 ); 979 cm −1 ( ν 1 ); 644 and 601 cm −1 ( ν 4 ); and 496 cm −1 ( ν 2 ) can be assigned to sulfate ligand in agreement with the literature and FTIR data (Figure S1) …”

Crystallographic and Spectroscopic Characterization of Americium Complexes Containing the Bis[(phosphino)methyl]pyridine-1-oxide (NOPOPO) Ligand Platform

“…Of the 111 entries in the Inorganic Crystal Structural Database (ICSD 2016 Version 1.9.8) containing diffraction data for americium compounds, only two of these were also found to be phosphorus-containing, , illustrating a clear lack of structural information available to help elucidate the interactions between minor actinides and phosphorus-containing groups, which play important roles in nuclear reprocessing. With this study, we are able to directly compare the molecular structures of trivalent and tetravalent lanthanide and actinide analogues in their organophosphorous environments with the aim of supporting the recent impetus to transition common structural assumptions in extraction chemistry regarding f element surrogates for highly radioactive elements to the realm of established fact. ,− …”

Complexation of Cyclic Glutarimidedioxime with Cerium: Surrogating for Redox Behavior of Plutonium

“…Cerium is a unique member of the lanthanide series with an accessible molecular chemistry in both the tetravalent and trivalent oxidation states. The ion size of Ce 4+ (0.97 Å) is close to that of Pu 4+ (0.96 Å), giving a similar shift in the trivalent and tetravalent redox potentials. , Ce 4+ ion is often presented as a relevant analogue of Pu 4+ ion. − The coordination chemistry of the Ce 3+ /Ce 4+ complex with glutarimidedioxime should parallel that of Pu 3+ /Pu 4+ . Therefore, the investigation of the Ce complexation with glutarimidedioxime ligands should provide a preliminary evaluation of the Pu complexation.…”