Cooperative Iron-Aluminium Reactivity for Dinitrogen Activation

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry
• Materials Science

Background:

• Nitrogen (N2) activation is crucial for industrial processes like ammonia synthesis.
• Developing efficient and cost-effective catalysts for N2 fixation remains a significant challenge.
• Bimetallic systems offer unique reactivity profiles for small molecule activation.

Purpose of the Study:

• To report a novel bimetallic approach for N2 activation using cooperative Fe-Al reactivity.
• To characterize the electronic structure and bonding of the N2-bridged Fe-Al complex.
• To demonstrate the utility of the Fe-Al platform for subsequent functionalization of activated N2.

Main Methods:

• Synthesis of a Cp*Fe(1,2-Cy2PC6H4AlEt) platform for N2 activation.
• Characterization using Mössbauer spectroscopy and density functional theory (DFT) calculations.
• Alkylation with n-butyllithium (nBuLi) followed by silylation.

Main Results:

• Successful capture of two N2 molecules via intermolecular Fe-N≡N-Al coordination.
• Determination of the N2-bridged Fe-Al dimer's electronic structure as a Fe(II)-Al(I)/Fe(0)-Al(III) resonance hybrid.
• Formation of a dinitrogen-lithiated complex enabling terminal nitrogen atom silylation.

Conclusions:

• The Fe-Al bimetallic system effectively activates N2 through cooperative reactivity.
• Fe-Al bonding acts as an electron buffer, facilitating facile N2 activation.
• This approach provides a new pathway for nitrogen fixation and functionalization.