Dinitrogen-Molybdenum Complex Induces Dinitrogen Cleavage by One-Electron Oxidation.

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry
• Nitrogen Fixation

Background:

• Dinitrogen (N2) cleavage is crucial for nitrogen fixation.
• Molybdenum complexes are key catalysts in nitrogen transformations.
• Understanding N2 activation mechanisms is vital for developing efficient synthetic routes.

Purpose of the Study:

• To investigate the N2 cleavage mechanism of trans-[Mo(depe)2(N2)2] (1) via one-electron oxidation.
• To synthesize and characterize the resulting molybdenum nitride complex.
• To elucidate the role of intermediate species in the N2 cleavage process.

Main Methods:

• One-electron oxidation using a mild oxidant ([Cp2Fe][BArf4]).
• Electrochemical oxidation of the molybdenum complex.
• In situ resonance Raman and UV-vis spectroscopies.
• Density-functional theory (DFT) calculations.

Main Results:

• Synthesis of the molybdenum(IV) terminal nitride complex [Mo(depe)2N][BArf4] (2) from complex 1.
• N2 cleavage occurs via a Mo(II)-N=N-Mo(II) intermediate.
• Electrochemical oxidation also yields complex 2, with a transient dimeric Mo complex detected.
• DFT calculations support a mechanism involving an unstable monomeric Mo(I) species and a dimeric intermediate with a zigzag transition state.

Conclusions:

• One-electron oxidation effectively cleaves the N2 ligand in trans-[Mo(depe)2(N2)2].
• A dimeric intermediate plays a critical role in the N2 cleavage pathway.
• This work provides mechanistic insights into molybdenum-mediated dinitrogen activation.