Hydrogen Bonding to a Dinitrogen Complex at Room Temperature: Impacts on N₂ Activation

Area of Science:

• Inorganic chemistry
• Bioinorganic chemistry
• Computational chemistry

Background:

• Metal dinitrogen complexes are crucial in nitrogen fixation.
• Understanding secondary sphere interactions is key to mimicking nitrogenase enzymes.
• Hydrogen bonding's role in modulating metal-nitrogen bonds requires further elucidation.

Purpose of the Study:

• To experimentally and computationally investigate hydrogen bonding effects on a rhenium(I) dinitrogen complex.
• To determine how varying hydrogen bond donor strength impacts the N-N bond.
• To provide insights into the mechanisms of nitrogenase enzymes.

Main Methods:

• Synthesis and characterization of a rhenium(I) dinitrogen complex.
• Spectroscopic analysis including 15N NMR and IR spectroscopy.
• Determination of association equilibria and Density Functional Theory (DFT) calculations.

Main Results:

• A series of hydrogen bond donors with a wide pKa range were studied.
• Hydrogen bonding was observed to polarize and weaken the N-N bond in the dinitrogen ligand.
• Experimental and computational data showed good agreement.

Conclusions:

• Hydrogen bonding significantly influences the electronic structure and reactivity of metal dinitrogen complexes.
• The findings elucidate the role of secondary sphere interactions in stabilizing and activating the N-N bond.
• This research contributes to the understanding of biological nitrogen fixation and the design of artificial systems.