Multiple pathways for dinitrogen activation during the reduction of an Fe Bis(iminepyridine) complex

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry
• Coordination Chemistry

Background:

• Bis(iminopyridine) iron complexes are relevant in catalysis and materials science.
• Dinitrogen activation is a key challenge in nitrogen fixation research.
• Understanding the role of alkali metals in transition metal complex reduction is crucial.

Purpose of the Study:

• To investigate the reduction of a bis(iminopyridine) FeCl(2) complex using sodium hydride (NaH).
• To explore the structural diversity arising from varying amounts of NaH.
• To elucidate the mechanisms of dinitrogen activation in these systems.

Main Methods:

• Chemical reduction of {2,6-[2,6-(iPr)(2)PhN=C(CH(3))](2)(C(5)H(3)N)}FeCl(2) using controlled amounts of NaH.
• Isolation and characterization of various iron-dinitrogen complexes via X-ray crystallography.
• Analysis of structural differences to infer reaction pathways and bonding modes.

Main Results:

• Formation of multiple iron-dinitrogen complexes (1-7) with varying structures and bonding modes depending on NaH stoichiometry.
• Complexes exhibit unique N(2) ligation to iron and interaction with sodium cations (e.g., terminal, side-on, sigma- and pi-bonding).
• Evidence for ligand deprotonation and formation of anionic ligands, influencing complex stability and reactivity.
• Identification of potential precursor-product relationships and aggregation phenomena.

Conclusions:

• The reduction of bis(iminopyridine) iron complexes with NaH provides access to a rich variety of dinitrogen species.
• Structural diversity highlights multiple pathways for dinitrogen activation and unique alkali metal cooperativity.
• These findings contribute to understanding fundamental aspects of nitrogen fixation and the reactivity of low-valent iron complexes.