Dihydrogen Adduct (Co-H₂ ) Complexes Displaying H-Atom and Hydride Transfer

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry
• Catalysis

Background:

• Transition metal dihydrogen complexes (M-H2) typically undergo oxidative addition or act as acids.
• Alternative H2 activation mechanisms, such as direct H-atom or hydride transfer, are less explored.

Purpose of the Study:

• To investigate novel H2 activation pathways via direct H-atom or hydride transfer from M-H2 adducts.
• To characterize the reactivity of neutral and anionic cobalt-dihydrogen complexes supported by a trisphosphine borane ligand (P3B).

Main Methods:

• Synthesis and characterization of neutral and anionic cobalt-dihydrogen complexes.
• Reactivity studies involving hydrogen atom transfer to a stable radical.
• Reactivity studies involving hydride transfer to a Lewis acid (BEt3).

Main Results:

• The neutral cobalt-dihydrogen complex, (P3B)Co(H2), acts as a precursor for hydrogen atom transfer.
• The anionic cobalt-dihydrogen complex, [(P3B)Co(H2)]1-, exhibits remarkable hydricity, enabling efficient hydride transfer.
• This hydride transfer capability is a novel finding for M-H2 complexes.

Conclusions:

• Dihydrogen complexes can activate H2 through direct H-atom or hydride transfer pathways.
• Anionic cobalt-dihydrogen complexes are potent hydride donors, expanding the known reactivity of M-H2 systems.
• This research opens new avenues for utilizing M-H2 complexes in catalysis and synthesis.