The Fe-MAN Challenge: Ferrates-Microkinetic Assessment of Numerical Quantum Chemistry

Area of Science:

• Organometallic Chemistry
• Physical Chemistry
• Computational Chemistry

Background:

• Organoferrate ions are key nucleophiles, but their reactions in solution are complex due to equilibria.
• Gas-phase experiments on mass-selected ions enable the study of individual species' reactivity.
• Understanding these reactions is crucial for fundamental chemical knowledge.

Purpose of the Study:

• To investigate the gas-phase protolysis reactions of trisarylferrate anions with fluorinated alcohols.
• To determine experimental bimolecular rate constants (k_exp) for these reactions.
• To evaluate the accuracy of computational methods in predicting these reaction parameters.

Main Methods:

• Mass-spectrometric measurements of gas-phase ion reactions.
• Proton transfer reactions involving trisarylferrate anions (FePh3-, FeMes3-) and fluorinated alcohols (2,2,2-trifluoroethanol, 2,2-difluoroethanol).
• A dual blind challenge for theoretical groups to predict activation barriers and rate constants (k_theo).

Main Results:

• Experimental bimolecular rate constants (k_exp) for the gas-phase protolysis were determined.
• Comparison between experimental and theoretical rate constants provides insights into computational method performance.
• The study establishes a benchmark for evaluating quantum chemical methods.

Conclusions:

• Gas-phase studies offer a clear view of organoferrate anion reactivity, overcoming solution complexities.
• The results facilitate the benchmarking of computational protocols for organometallic reaction prediction.
• This work paves the way for improved quantum chemical methods and data-driven approaches.