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

Herein, we report the synthesis and structural characterization of K₈[(CO₃)₃Pu]₂(μ-η²-η²-O₂)₂·12H₂O. This is the second Pu-containing addition to the previously studied alkali-metal peroxocarbonate series M₈[(CO₃)₃A]₂(μ-η²-η²-O₂)₂·<i>x</i>H₂O (M = alkali metal; A = Ce or Pu; <i>x</i> = 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 Na₈[(CO₃)₃Pu]₂(μ-η²-η²-O₂)₂·12H₂O is not isomorphous with its known Ce analogue. However, a new synthetic route to these M₈[(CO₃)₃A]₂(μ-η²-η²-O₂)₂·12H₂O complexes, described below, has produced crystals of Na₈[(CO₃)₃Ce]₂(μ-η²-η²-O₂)₂·12H₂O that <i>are</i> isomorphous with the previously reported Pu analogue. Via this synthetic method, the M = Na, K, Rb, and Cs salts of M₈[(CO₃)₃Ce]₂(μ-η²-η²-O₂)₂·<i>x</i>H₂O 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_p–O_p stretch (O_p = O atoms of the peroxide bridges) with each of the cations studied: Na⁺ [1.492(3) Å/847 cm^–1], Rb⁺ [1.471(1) Å/854 cm^–1], Cs⁺ [1.474(1) Å/859 cm^–1], and K⁺ [1.468(6) Å/870 cm^–1]. The trends observed in the O_p–O_p bond distances appear to relate to supermolecular interactions between the neighboring cations

Synthesis, spectroscopic characterization and crystal structures of thorium(IV) mononuclear lactato and hexanuclear formato complexes

Two thorium(Th) complexes with lactate or formate have been synthesized and characterized. Th(C3H5O3)4(H2O)2 (1) [C3H5O3H = lactic acid] has a mononuclear structure with ten-fold coordinated Th polyhedron in deformed bicapped square antiprism by four chelating lactate ligands via both carboxylate O and the alcohol O atoms in addition to two coordinated water molecules. The lactate ligands are enantiomer with equal proportion of R- and S-isomers. [Th6(O)4(OH)4(HCO2)12(H2O)6]•5H2O (2) [HCO2H = formic acid] is a hexanuclear Th nanocluster constructed by four oxo-, four hydroxyl, twelve μ2-bridging formate ligands and six water molecules. The calculated bond valence sums are in good agreement with the presence of equal numbers of oxo- and hydroxyl groups in the cluster. Thermal studies confirmed that both complexes lost water molecules first followed by the decomposition of the organic ligands to form ThO2 as the final product. The presence of bridging OH-groups in both complexes has been proven by Raman spectroscopy