Nickel(II/IV) Manifold Enables Room-Temperature C(sp³)-H Functionalization

Area of Science:

• Organometallic Chemistry
• Catalysis
• Synthetic Chemistry

Background:

• C(sp3)-H activation is crucial for organic synthesis.
• Nickel-catalyzed C-H activation often requires harsh conditions or specific Ni oxidation states.

Purpose of the Study:

• To demonstrate a mild, room-temperature C(sp3)-H activation using a high-valent nickel center.
• To explore the mechanism and scope of this novel transformation.
• To develop a catalytic C(sp3)-H functionalization reaction.

Main Methods:

• Oxidative induction of C(sp3)-H activation at a high-valent nickel complex.
• Isolation and characterization of a nickel-IV sigma-alkyl complex.
• Density functional theory (DFT) calculations to elucidate reaction mechanisms.
• Stoichiometric and catalytic C(sp3)-H functionalization reactions.

Main Results:

• A mild, room-temperature C(sp3)-H activation was achieved at a high-valent nickel center.
• An isolable nickel-IV sigma-alkyl complex was generated.
• DFT studies identified two plausible mechanisms, with a Ni-IV pathway being modestly favored.
• The Ni-IV intermediate reacted with various nucleophiles to form C(sp3)-X bonds.
• A proof-of-principle Ni(II/IV)-catalyzed C(sp3)-H functionalization was demonstrated.

Conclusions:

• Mild C(sp3)-H activation at high-valent nickel is feasible at room temperature.
• The generated Ni-IV intermediate is a versatile species for C-X bond formation.
• This work provides a foundation for developing new catalytic C-H functionalization strategies.