N₂ Functionalization via Molybdenum-Nitride Complex: Stepwise BH Bond Additions

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry
• Nitrogen Fixation

Background:

• Nitrogen splitting by transition metal complexes is a key step towards nitrogen functionalization.
• Understanding the reactivity of metal-nitrido species is crucial for developing new catalytic processes.

Purpose of the Study:

• To investigate the reactivity of a (triphosphine)molybdenum(IV)-nitrido complex towards boranes.
• To elucidate the reaction mechanisms and characterize the resulting adducts and complexes.

Main Methods:

• Synthesis and characterization of the (triphosphine)Mo(IV)-nitrido complex.
• Reactions with various borane reagents (BH3.SMe2, 9-BBN).
• Spectroscopic analysis (NMR, X-ray crystallography) to determine structures.

Main Results:

• Formation of a simple adduct Mo≡N→BH3 with BH3.SMe2.
• Evidence of 1,2-addition with 9-BBN, yielding H-Mo=NBR2.
• Observation of an unprecedented complex with two bridging hydrogens after a second BH3.SMe2 addition.
• Reductive elimination and N-H bond formation promoted by PMe3 or BH3.SMe2.

Conclusions:

• The study demonstrates a full sequence of functionalization at the Mo≡N moiety after N2 splitting.
• New reaction pathways and unprecedented complexes involving molybdenum-nitrido and borane interactions were discovered.
• This work provides insights into the controlled functionalization of nitrogen coordinated to transition metals.