An Open-Shell Fe^IV Nitrido

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry
• Photocatalysis

Background:

• Terminal iron nitrido complexes are crucial intermediates in nitrogen fixation and catalytic cycles.
• Understanding the electronic structure of iron nitrido species is key to controlling their reactivity.
• Previous studies have focused on low-spin iron nitrido analogues, limiting observed reactivity modes.

Purpose of the Study:

• To photogenerate and characterize a novel open-shell, terminal iron nitrido complex.
• To elucidate the electronic ground state and structural properties of the synthesized iron nitrido.
• To explore the reactivity of this iron nitrido species, particularly in comparison to low-spin analogues.

Main Methods:

• Synthesis and characterization of an iron nitrido complex using a sterically encumbered dipyrrin ligand.
• Solid-state structural analysis and zero-field 57Fe Mössbauer spectroscopy.
• Computational analysis to determine the electronic ground state and bonding characteristics.

Main Results:

• Successful photogeneration and characterization of an open-shell, terminal iron nitrido complex, (EmL)Fe(N).
• Evidence from structural data, Mössbauer spectroscopy, and computation indicates a triplet electronic ground state.
• The iron nitrido complex displays attenuated Fe-N multiple bond character, enabling novel reactivity.

Conclusions:

• The triplet ground state iron nitrido complex exhibits unique reactivity not seen in low-spin analogues.
• This includes primary C(sp3)-H amination, H2 cleavage, aromatic C-C cleavage, and photocatalytic N-atom transfer.
• This work expands the known reactivity landscape of iron nitrido compounds and opens new avenues in catalysis.