Synthesis, Structural, and Electronic Properties of K 4 Pu VI O 2(CO 3) 3(cr): An Environmentally Relevant Plutonium Carbonate Complex

TL;DR

This study synthesizes and characterizes the plutonium(VI) carbonate complex K4PuVIO2(CO3)3, analyzing its structure and electronic properties to better understand its environmental and nuclear relevance, and compares it with analogous uranium and neptunium compounds.

Contribution

It provides the first detailed crystallographic, spectroscopic, and electronic analysis of the PuVI carbonate complex, filling gaps in data for actinide chemistry relevant to nuclear technology.

Findings

Crystallographic structure of PuVI complex determined.

Correlation of actinyl bond lengths across U, Np, Pu series.

Electronic structure insights into PuVI oxidation state and local environment.

Abstract

The chemical properties of actinide materials are often predefined and described based on the data available for isostructural species. This is the case for potassium plutonyl (PuVI) carbonate, K4PuVIO2(CO3)3(cr), a complex relevant for nuclear technology and the environment, of which the crystallographic and thermodynamic properties of which are still lacking. We report here the synthesis and characterization of PuVI achieved by single-crystal X-ray diffraction analysis and high-energy-resolution fluorescence-detected X-ray absorption near-edge structure at the Pu M4-edge coupled with electronic structure calculations. The crystallographic properties of PuVI are compared with isostructural uranium (U) and neptunium (Np) compounds. Actinyl (AnVI) axial bond lengths, [O-AnVI-O]2+, are correlated between solid, K4AnVIO2(CO3)3(cr), and aqueous, [AnVIO2(CO3)3]4-(aq) species for the UVI-NpVI-PuVI series. The spectroscopic data are compared to KPuVO2CO3(cr) and PuIVO2(cr) to tackle the trend in the electronic structure of PuVI regarding the oxidation state changes and local structural modifications around the Pu atom