CO reductive oligomerization by a divalent thulium complex and CO₂-induced functionalization.

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry
• Catalysis

Background:

• Carbon monoxide (CO) is a fundamental C1 building block in chemistry.
• Homologation of CO into multicarbon ligands is crucial for synthesizing complex organic molecules.
• Lanthanide complexes offer unique electronic properties for small molecule activation.

Purpose of the Study:

• To investigate the reactivity of divalent thulium complexes with carbon monoxide.
• To explore the formation and subsequent reactions of CO-derived multicarbon complexes.
• To understand the mechanism of CO homologation and functionalization.

Main Methods:

• Synthesis and characterization of thulium-cyclopentadienyl complexes.
• Reactions of thulium complexes with carbon monoxide (CO).
• Density Functional Theory (DFT) calculations to elucidate reaction mechanisms.
• Reactions of CO-derived complexes with electrophiles and carbon dioxide (CO2).

Main Results:

• Selective reductive dimerization and trimerization of CO by [Tm(Cp^ttt)₂] to form C2 (ethynediolate) and C3 (ketenecarboxylate) complexes.
• Rearrangement of the C2 complex into a 3,4-dihydroxyfuran-2-one complex upon treatment with Me₃SiI.
• Unusual functionalization of C2 and C3 complexes with electrophiles and CO2.
• CO2-induced C-H activation of aromatic solvents by the C2 complex, functionalizing CO-derived ligands.

Conclusions:

• Divalent thulium complexes can mediate selective CO homologation.
• CO-derived ligands exhibit novel reactivity, including rearrangements and functionalization.
• CO2 can act as an activator for C-H functionalization of CO-derived ligands, demonstrating unprecedented intermolecular reactivity.