CO₂ conversion to phenyl isocyanates by uranium(vi) bis(imido) complexes.

Area of Science:

• Organometallic Chemistry
• Uranium Chemistry
• Inorganic Chemistry

Background:

• Uranium(VI) complexes with imido ligands are of interest for their unique reactivity.
• Understanding the reaction of these complexes with small molecules like CO2 is crucial for developing new synthetic methodologies.

Purpose of the Study:

• To investigate the reaction of uranium(VI) trans-bis(imido) complexes with carbon dioxide.
• To characterize the resulting products and elucidate the reaction mechanism.

Main Methods:

• Synthesis and characterization of uranium(VI) trans-bis(imido) complexes.
• Reaction of complexes with CO2.
• Crystallographic characterization of a uranium-oxo complex.
• Density Functional Theory (DFT) studies to probe the reaction mechanism.

Main Results:

• Uranium(VI) bis(imido) complexes react with CO2 to eliminate phenyl isocyanates.
• New uranium(VI) trans-dioxo or oxo-imido complexes are formed.
• Crystallographic data confirmed the structure of a uranium(VI) oxo complex.
• DFT calculations revealed an endergonic cycloaddition intermediate formation.
• The subsequent formation of a dioxo uranyl species is thermodynamically and kinetically hindered.

Conclusions:

• The reaction of uranium(VI) bis(imido) complexes with CO2 offers a pathway to novel uranium-oxo and uranium-dioxo species.
• The reaction mechanism involves a cycloaddition intermediate, with subsequent transformations being disfavored.
• This work expands the understanding of uranium imido complex reactivity and provides insights into uranium-oxo complex formation.