A DFT-Based Protocol for Modeling the Structure and Reactivity of Gold(III) Complexes

Area of Science:

• Computational Chemistry
• Inorganic Chemistry
• Reaction Kinetics

Background:

• Gold(III) complexes are relevant in medicinal chemistry and catalysis.
• Understanding their reaction mechanisms, like aquation, is crucial for application.
• Accurate computational methods are needed to predict kinetic properties.

Purpose of the Study:

• To investigate the influence of computational protocols on Au(III) complex aquation.
• To identify optimal computational parameters for predicting kinetic properties.
• To evaluate structure and activation Gibbs free energy sensitivity to computational choices.

Main Methods:

• Assessed 154 nonrelativistic and 7 relativistic computational protocols.
• Varied basis sets for gold (Au) and ligand atoms, and levels of theory (HF, MP2, DFT).
• Evaluated 397 combinations of computational parameters.

Main Results:

• Complex structure showed low sensitivity to computational protocols.
• Activation Gibbs free energy was highly sensitive to theory level and basis sets.
• Ligand basis sets critically influence kinetic parameter accuracy.

Conclusions:

• B3LYP/def2-SVP/6-31G(d,p) protocol showed best agreement for the reference complex.
• Diffuse functions on ligand atoms (6-31+G(d)) are essential for bulkier derivatives.
• A balanced protocol (B3LYP/Stuttgart-RSC ECP/6-31+G(d)) is recommended for various Au(III) complexes.