Terminal Iron Carbyne Complexes Derived from Arrested CO₂ Reductive Disproportionation

Area of Science:

• Organometallic chemistry
• Coordination chemistry
• Carbon dioxide utilization

Background:

• The reactivity of metal cyanide complexes with small molecules like CO2 is a key area in catalysis and materials science.
• Understanding the transformation pathways of CO2 is crucial for developing sustainable chemical processes.

Purpose of the Study:

• To investigate the reaction of an encumbered iron tetraisocyanide dianion with carbon dioxide.
• To explore the influence of silyl triflates on the CO2 reaction pathway.
• To characterize the resulting iron-carbon multiply bonded species.

Main Methods:

• Synthesis and characterization of iron-isocyanide complexes.
• Reaction of the iron complex with carbon dioxide in the presence of silyl triflates.
• Crystallographic, spectroscopic (e.g., NMR, IR), and computational analyses (e.g., DFT) of the products.

Main Results:

• The iron complex undergoes reductive disproportionation with CO2 to form CO and carbonate.
• In the presence of silyl triflates, the reaction is arrested, forming a mono-CO2 adduct.
• This adduct is converted into four-coordinate terminal iron carbynes with aryl carbamate substituents.
• Structural and electronic analyses confirm a conformationally locked iron carbyne unit.

Conclusions:

• The study reveals a novel pathway for CO2 activation and functionalization using an iron complex.
• Silyl triflates enable the isolation of unique iron carbyne intermediates.
• The characterized iron carbynes represent a new class of organometallic compounds with potential applications in catalysis.