Diarylpnictogenyldialkylalanes─Synthesis, Structures, Bonding Analysis, and CO₂ Capture

Area of Science:

• Organometallic Chemistry
• Main Group Chemistry
• Coordination Chemistry

Background:

• The field of monomeric pnictogenylalanes is relatively small.
• Characterization of aluminum compounds with bulky substituents is important for understanding their stability and reactivity.

Purpose of the Study:

• To synthesize and characterize new diphenylamino- and diphenylphosphanyldialkylalanes.
• To investigate the reactivity of these compounds with σ-donor ligands and carbon dioxide.
• To elucidate reaction mechanisms using DFT calculations.

Main Methods:

• Synthesis of novel aluminum compounds.
• Structural characterization using single crystal X-ray diffraction.
• Spectroscopic characterization in solution.
• Density Functional Theory (DFT) calculations for bonding analysis and mechanism elucidation.

Main Results:

• Stable monomeric diphenylamino- and diphenylphosphanyldialkylalanes with bulky alkyl substituents were synthesized and structurally characterized.
• Oligomeric diphenylpnictogenyldimethylalanes reacted with σ-donor ligands to form monomeric adducts, including the first cyclic(alkyl)(amino)carbene (CAAC) complexes.
• Reactivity studies with CO2 revealed different insertion products for CAAC complexes, oligomeric precursors, and monomeric aminoalanes.

Conclusions:

• The study expands the known range of stable monomeric pnictogenylalanes.
• Novel CAAC complexes were synthesized and their reactivity explored.
• DFT calculations provided insights into reaction mechanisms involving CO2 insertion.