Rapid, Reversible, Solid-Gas and Solution-Phase Insertion of CO2 into In-P Bonds

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry
• Materials Science

Background:

• Heteroleptic indium complexes offer unique reactivity.
• Phosphorus-based ligands are crucial in stabilizing metal centers.
• Carbon dioxide activation is a key area in sustainable chemistry.

Purpose of the Study:

• To synthesize and characterize a novel P,P-chelated heteroleptic indium chloride complex.
• To investigate the reactivity of this complex with carbon dioxide.
• To explore the stability and decomposition pathways of the CO2 adduct.

Main Methods:

• Synthesis of bis[bis(diisopropylphosphino)amido]indium chloride via reaction of InCl3 with (i-Pr2P)2NLi.
• Exposure of the indium complex to CO2 in various states (slurry, solution, solid-state).
• Characterization using multinuclear NMR, IR spectroscopy, and single-crystal X-ray diffraction.
• In-situ ReactIR studies to monitor reaction kinetics.
• Thermal stability studies under vacuum.

Main Results:

• High yield synthesis of [(i-Pr2P)2N]2InCl.
• Successful insertion of CO2 into two M-P bonds, forming [O2CP(i-Pr2)NP(i-Pr2)]2InCl.
• Rapid reaction kinetics observed in solution (<1 min) and solid-gas phase (<2 h).
• The CO2 adduct exhibits stability up to 60 °C, decomposing above 75 °C.
• Reaction with CS2 yields a complex mixture including a CS2 cleavage product.

Conclusions:

• The P,P-chelated indium complex readily reacts with CO2, demonstrating efficient CO2 insertion into M-P bonds.
• The resulting CO2 adduct is thermally sensitive, reversibly decomposing upon heating.
• The complex shows different reactivity patterns with CS2 compared to CO2.