Aluminum(I)/Boron(III) Redox Reactions

Area of Science:

• Organometallic Chemistry
• Main Group Chemistry
• Boron Chemistry
• Aluminum Chemistry

Background:

• Cyclopentadienyl-stabilized aluminum(I) reagents offer unique reactivity.
• Boron(III) compounds are versatile electrophiles.
• Understanding Al/B interactions is crucial for novel material synthesis.

Purpose of the Study:

• To investigate the reactions between a novel aluminum(I) reagent and various boron(III) species.
• To explore the formation of diverse Al/B complexes with different oxidation states and coordination geometries.
• To demonstrate the reduction of boron(III) to borylenes using p-block reagents.

Main Methods:

• Reaction of cyclopentadienyl-stabilized Al(I) reagent (1) with different boron(III) compounds (e.g., B(C6F5)3, aryldihaloboranes, borenium ions, BI3).
• Characterization of resulting complexes using spectroscopic and crystallographic techniques.
• Analysis of Al/B oxidation states and coordination geometries.

Main Results:

• Formation of an Al(I)→B(III) adduct with B(C6F5)3.
• Oxidative addition with bulky aryldihaloboranes yielding bora-alane species.
• Redox reaction with borenium ions forming borylene-alane B(I)→Al(III) complexes.
• Complete substituent scrambling and formation of a B(I)→AlI3 complex with BI3.
• Demonstration of the first p-block reagent-mediated reduction of B(III) to borylenes.

Conclusions:

• Subtle changes in borane structure lead to divergent reaction pathways and diverse Al/B complexes.
• The novel Al(I) reagent is a versatile tool for synthesizing unique organoboron and organoaluminum compounds.
• These findings open new avenues for the synthesis of low-valent boron species and Al/B materials.