Dinitrogen activation upon reduction of a triiron(II) complex

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry
• Catalysis

Background:

• Dinitrogen (N2) is a stable molecule, making its activation challenging.
• Nitrogen fixation is crucial for life and industrial processes.
• Iron complexes are being investigated as potential catalysts for N2 activation.

Purpose of the Study:

• To investigate the reactivity of a trinuclear iron(II) complex with dinitrogen.
• To characterize the products of dinitrogen activation and reduction.
• To explore the potential for ammonia synthesis from N2 using iron complexes.

Main Methods:

• Reaction of a trinuclear iron(II) complex (Fe3Br3L) with KC8 under N2 atmosphere.
• Characterization of products using X-ray crystallography, 1H NMR, IR, and Mössbauer spectroscopy.
• Detection and quantification of ammonia using the indophenol assay.

Main Results:

• Dinitrogen activation products were formed, including a trinuclear iron complex with protonated N-atom bridges (Fe3(NH)3L).
• Protonolysis of the activated dinitrogen product yielded ammonia with approximately 30% yield.
• Spectroscopic and crystallographic data confirmed the structure of the iron-nitrogen species.

Conclusions:

• The trinuclear iron complex facilitates dinitrogen activation and subsequent reduction to ammonia.
• The study provides evidence for protonated N-atom bridges in the iron-nitrogen reduction product.
• This work contributes to the understanding of iron-mediated nitrogen fixation and ammonia synthesis.