Iron and manganese oxo complexes, oxo wall and beyond

Area of Science:

• Inorganic Chemistry
• Catalysis
• Bioinorganic Chemistry

Background:

• High-valent metal-oxo species are key intermediates in biological and abiological oxidation reactions, such as alkane hydroxylation and olefin epoxidation.
• Examples include iron-oxo species in cytochrome P450 enzymes and manganese-oxo species in photosystem II.
• Synthetic efforts have yielded numerous iron-oxo and manganese-oxo complexes, inspiring the study of functional mimics.

Purpose of the Study:

• To review mononuclear non-haem Fe-O and Mn-O species.
• To explain the electronic instability of late transition metal-oxo complexes, known as the 'oxo wall'.
• To highlight recent advancements in synthesizing oxo complexes of cobalt, nickel, and copper that overcome the 'oxo wall'.

Main Methods:

• Spectroscopic analysis of metal-oxo complexes.
• Theoretical calculations to understand electronic structures and stability.
• Synthesis of novel high-valent transition metal-oxo complexes.

Main Results:

• The 'oxo wall' concept explains the rarity of late transition metal-oxo complexes with tetragonal symmetry.
• A few late metal-oxo complexes have been successfully synthesized by exploring alternative symmetries and spin states.
• These studies provide insights into the fundamental chemistry of high-valent metal-oxo species.

Conclusions:

• Overcoming the 'oxo wall' is crucial for expanding the scope of late transition metal-oxo chemistry.
• Recent synthetic strategies have enabled the preparation of previously inaccessible oxo complexes of Co, Ni, and Cu.
• This research advances the development of functional mimics for catalytic oxidation reactions.