Activation of CO₂, CS₂, and COS by α-Diimine-Stabilized Gallylenes

Area of Science:

• Organometallic Chemistry
• Main Group Chemistry
• Coordination Chemistry

Background:

• Gallium complexes with α-diimine ligands are known but their reactivity with small molecules is less explored.
• Understanding the reactivity of main group elements with CO2 and its analogues is crucial for catalysis and materials science.

Purpose of the Study:

• To synthesize and characterize novel gallium complexes stabilized by an α-diimine ligand.
• To investigate the reactivity of these gallium complexes towards carbon dioxide (CO2) and its sulfurized analogues (CS2, COS).
• To explore new reaction pathways and product formations, including reductive disproportionation and coupling.

Main Methods:

• Synthesis of gallylenes [LPhGaM(THF)n] stabilized by an α-diimine ligand (LPh).
• Reaction of the gallium complexes with CO2, CS2, and COS under varying conditions.
• Characterization of the resulting complexes using spectroscopic and crystallographic techniques.

Main Results:

• Preparation of several gallylenes [LPhGaM(THF)n] (M=Li, Na, K).
• Reaction with CO2 yielded a trimeric carbonate complex and a dinuclear oxo-carbonate complex via reductive disproportionation.
• Reaction with CS2 afforded two ethenetetrathiolate gallium complexes via reductive coupling.
• Reaction with COS resulted in a disulfide-bridged complex at room temperature and a dithiocarbonate complex at low temperature.

Conclusions:

• The synthesized gallylenes exhibit diverse reactivity towards CO2 and its sulfurized analogues.
• New pathways for the transformation of CO2 and its analogues involving gallium complexes have been demonstrated.
• The study reports the first example of dithiocarbonates of p-block elements.