Azobenzene Reduction and Derivatization and Al-H Bond Insertion with β‑Diketiminate Gallium(I) Complexes

Area of Science:

• Organometallic Chemistry
• Main Group Chemistry
• Ligand Design

Background:

• β-diketiminate ligands are versatile scaffolds in coordination chemistry.
• Low-oxidation-state main group elements offer unique reactivity.
• Gallium(I) complexes are less explored compared to their higher oxidation state counterparts.

Purpose of the Study:

• To synthesize novel β-diketiminate gallium(I) complexes with modified ligand backbones.
• To investigate the reactivity of these gallium(I) complexes with azobenzene and other reagents.
• To explore the potential of these complexes as alternatives for studying low-oxidation-state gallium chemistry.

Main Methods:

• Synthesis of new β-diketiminate ligands with varying backbone substituents (R = Et, iPr).
• Preparation of gallium(I) complexes via salt metathesis/reduction using "GaI".
• Reactions of gallium(I) complexes with azobenzene, DMSO, benzaldehyde, and aluminum hydride complexes.

Main Results:

• Successfully synthesized two new gallium(I) complexes, [(EtDipnacnac)-Ga] and [(iPrDipnacnac)-Ga], with varying yields influenced by ligand backbone substitution.
• Converted gallium(I) complexes to gallium(III) complexes via reaction with azobenzene, forming N,ortho-C-(H)-chelating coordination.
• Observed further transformations including C-H activation, DMSO deprotonation, C-N coupling, and formation of Ga-Al bonded complexes.

Conclusions:

• Ligand backbone modification significantly influences the success of gallium(I) complex synthesis.
• The synthesized gallium(I) complexes exhibit diverse reactivity, enabling the formation of various gallium(III) and Ga-Al species.
• The Et-substituted gallium(I) complex serves as a viable alternative to commonly used methyl-substituted complexes for low-oxidation-state gallium studies.