f-Block reactions of metal cations with carbon dioxide studied by inductively coupled plasma tandem mass spectrometry

• Published in: Physical chemistry chemical physics : PCCP Vol. 26; no. 1; pp. 29 - 218
• Main Authors: Cox, Richard M, Melby, Kali M, French, Amanda D, Rodriguez, Michael J
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 21.12.2023; Royal Society of Chemistry (RSC)
• Subjects: Carbon dioxide; Cations; Inductively coupled plasma; Mass spectrometry; Metal oxides; Oxidation
• ISSN: 1463-9076; 1463-9084; 1463-9084
• DOI: 10.1039/d3cp04180h

f-Block chemistry offers an opportunity to test current knowledge of chemical reactivity. The energy dependence of lanthanide cation (Ln + = Ce + , Pr + , Nd + -Eu + ) and actinide cation (An + = Th + , U + -Am + ) oxidation reactions by CO 2 , was observed by inductively coupled plasma tandem mass spectrometry. This reaction is commonly spin-unallowed because the neutral reactant (CO 2 , 1 Σ + g ) and product (CO, 1 Σ + ) require the metal and metal oxide cations to have the same spin state. Correlation of the promotion energy ( E p ) to the first state with two free d-electrons with the reaction efficiency indicates that spin conservation is not a primary factor in the reaction rate. The E p likely influences the reaction rate by partially setting the crossing between the ground and reactive states. Comparison of Ln + and An + congener reactivity indicates that the 5f-orbitals play a small role in the An + reactions. The reaction rates of lanthanide and actinide cations with CO 2 are dictated by the crossing between the potential energy surface (PES) evolving from the ground state reactants (red) and the PES leading to the ground state products (green).