In Crystallo O₂ Cleavage at a Preorganized Triiron Cluster

Area of Science:

• Bioinorganic Chemistry
• Catalysis
• Materials Science

Background:

• Nature utilizes multimetallic active sites for efficient four-electron reduction of O₂.
• These sites feature precisely positioned metal centers for rapid O₂ activation, preventing toxic intermediates.
• Biomimetic constructs that replicate these complex active sites are rare.

Purpose of the Study:

• To report solid-state O₂ activation at a novel triiron(II) active site.
• To investigate the structure and reactivity of O₂ reduction intermediates.
• To provide detailed insights into multimetallic active site dynamics.

Main Methods:

• Solid-state O₂ dosing experiments.
• In crystallo studies.
• Spectroscopic, structural, magnetic, and computational analyses.

Main Results:

• Formation of an Fe₂^IIIFe^IV-dioxo intermediate upon O₂ exposure.
• Demonstrated oxygen atom and hydrogen atom transfer reactivity.
• Characterization of a stable Fe^IIFe₂^III-oxo species.

Conclusions:

• The phosphinimide-templated triiron(II) active site facilitates O₂ activation in the solid state.
• Detailed mechanistic insights into bond-forming and -breaking processes were obtained.
• This work advances the design of biomimetic catalysts for O₂ transformations.