Ferric-Thiolate Bond Dissociation Studied with Electronic Structure Calculations

Area of Science:

• Inorganic Chemistry
• Computational Chemistry
• Biochemistry

Background:

• Iron-sulfur clusters are vital prosthetic groups in biological systems.
• Their stability and reactivity are crucial for biological function.
• Understanding ferric-thiolate bond dissociation is key to their mechanism.

Purpose of the Study:

• To investigate the ferric-thiolate bond dissociation mechanism in model iron-sulfur complexes.
• To compare computational methods for accuracy and efficiency.
• To identify suitable density functionals for studying these reactions.

Main Methods:

• High-level ab initio multiconfigurational electronic structure calculations.
• Analysis of reaction mechanisms, including spin-crossing.
• Comparison of various density functionals and semiempirical methods.

Main Results:

• The reaction proceeds via a homolytic mechanism.
• A spin-crossing occurs from a sextet reactant state to a quartet product state.
• M06 and OPTX-based functionals demonstrated the best performance in modeling the reaction.

Conclusions:

• The homolytic dissociation with spin-crossing is the primary mechanism.
• M06 and OPTX functionals offer a computationally efficient and accurate approach.
• These findings aid in understanding iron-sulfur cluster reactivity.