Systematic improvement of redox potential calculation of Fe(III)/Fe(II) complexes using a three-layer micro-solvation...

Area of Science:

• Computational chemistry
• Physical chemistry
• Electrochemistry

Background:

• Modeling electrochemical transformations of metal ions in aqueous solutions is complex due to dynamic solvation structures.
• Accurate atomistic-scale modeling is crucial but often computationally expensive.

Purpose of the Study:

• To develop a simple, fast, and accurate three-layer micro-solvation model for evaluating metal ion redox potentials in aqueous solutions.
• To validate the model for Fe3+/Fe2+ redox potentials and demonstrate its general applicability to other metal complexes.

Main Methods:

• Combines DFT-based geometry optimizations of metal complexes with explicit water layers and an implicit solvation model.
• The model captures solute-solvent interactions and bulk solvent effects for accurate redox potential calculations.
• Validated using DFT functionals like ωB97X-V, ωB97X-D3, ωB97M-V, and B3LYP-D3.

Main Results:

• Achieved high accuracy for Fe3+/Fe2+ redox potentials with errors as low as 0.01 V.
• Successfully applied to the Fe(CN)63-/4- system and other metal complexes, showing close agreement with experimental values (0.07 V error).
• Demonstrated an average error of 0.21 V across five different metal systems.

Conclusions:

• The developed three-layer micro-solvation model offers a computationally efficient and accurate approach for predicting metal ion redox potentials.
• The model shows broad applicability for various chemical and industrial processes involving metal ions.
• Enhances the feasibility of atomistic-scale modeling for understanding solvation architectures and redox behavior.