Intramolecular C-N bond activation by a transient boryl anion

Area of Science:

• Organoboron chemistry
• Coordination chemistry
• Main group element reactivity

Background:

• Diamido ligands offer versatile coordination environments for main group elements.
• Bulky boron compounds are key intermediates in synthesizing novel boron species.
• Understanding cooperative activation of small molecules is crucial in catalysis.

Purpose of the Study:

• To synthesize a novel bulky boron bromide with a flexible diamido framework.
• To investigate the reactivity of the boron bromide precursor towards reduction and nucleophilic attack.
• To explore cooperative small molecule activation involving boron and transition metal complexes.

Main Methods:

• Synthesis of a sterically demanding boron bromide using a diamido ligand.
• Reductive activation using lithium metal to induce intramolecular C-N bond cleavage.
• Reaction with potassium bis(carbonyl)cyclopentadienyliron to study cooperative CO activation.

Main Results:

• A boron bromide with an exceptionally wide N-B-N angle was successfully prepared.
• Intramolecular C-N bond activation and aryl migration to boron were observed upon reduction.
• Nucleophilic attack by a carbonyl oxygen and cooperative CO activation were demonstrated with the iron complex.

Conclusions:

• The flexible diamido framework enables the formation of unique boron structures with unusual bonding angles.
• Reductive conditions can trigger C-N bond activation and aryl migration, offering a pathway to new organoboron compounds.
• Cooperative activation of carbon monoxide by boron and transition metal centers highlights novel reactivity patterns.