Magnesium-stabilised transition metal formyl complexes: structures, bonding, and ethenediolate formation

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry
• Catalysis

Background:

• Transition metal formyl complexes are crucial but often transient intermediates in carbon monoxide (CO) chemistry.
• Understanding their structure and reactivity is key to developing new catalytic processes for CO utilization.

Purpose of the Study:

• To synthesize and characterize a comprehensive series of transition metal formyl complexes.
• To investigate the bonding and electronic properties of these novel complexes.
• To explore the reactivity of formyl complexes in C-C bond formation reactions.

Main Methods:

• Crystallographic characterization of synthesized transition metal formyl complexes.
• Density Functional Theory (DFT) calculations to probe electronic structure and reaction mechanisms.
• Investigation of reaction pathways, including C-C coupling.

Main Results:

• First comprehensive series of crystallographically characterized transition metal formyl complexes (Cr, Mn, Fe, Co, Rh, W, Ir).
• Formyl ligand is chelated between a transition metal and a magnesium cation, exhibiting significant oxycarbene character.
• A heterometallic Cr-Mg formyl complex underwent C-C coupling to form an ethenediolate complex, with DFT supporting the formyl intermediate's role.

Conclusions:

• Well-defined transition metal formyl complexes are accessible and stable.
• These complexes serve as valuable intermediates in CO homologation reactions.
• The observed C-C coupling demonstrates a new reactivity pathway for formyl complexes.