Bora-alkenes: Metal Coordination and Reactions with BH-boranes

Area of Science:

• Organoboron Chemistry
• Organometallic Chemistry
• Carbene Chemistry

Background:

• N-heterocyclic carbenes (NHCs) are versatile ligands in organometallic chemistry.
• Bora-alkenes, containing a boron-carbon double bond, offer unique reactivity.
• Stabilization of reactive species like bora-alkenes is crucial for their study and application.

Purpose of the Study:

• To synthesize and characterize a neutral N-heterocyclic carbene stabilized bora-alkene.
• To investigate the coordination chemistry of the bora-alkene with transition metals (copper, gold, palladium).
• To explore the reactivity of the bora-alkene in hydroboration reactions with different boranes.

Main Methods:

• Preparation of the bora-alkene via a BH borenium/hydroboration route.
• Formation and characterization of π-complexes with copper, gold, and palladium.
• Regioselective hydroboration reactions using (C6F5)2BH and C6F5BH2·SMe2 boranes.

Main Results:

• A stable, neutral N-heterocyclic carbene stabilized bora-alkene (1) was successfully synthesized.
• The bora-alkene forms stable π-complexes with copper, gold, and palladium.
• Regioselective hydroboration occurred with the specified boranes, with one reaction involving rearrangement and substituent exchange.

Conclusions:

• N-heterocyclic carbene stabilization provides access to reactive bora-alkene species.
• The synthesized bora-alkene exhibits versatile coordination chemistry with late transition metals.
• The study demonstrates the potential for controlled hydroboration and rearrangement reactions involving bora-alkenes and boranes.