Nickel-Catalyzed Selective Reduction of Carbon Monoxide with Magnesium Alkyl Compounds.

Research on CO activation and homologation is pivotal for promoting sustainable chemistry and the construction of Cn molecular blocks. This work reports the nickel-catalyzed reduction of CO by magnesium alkyl compounds utilizing a bimetallic Mg/Ni synergistic strategy. The exposure of β-diketiminato ligand-supported magnesium monoalkyl compounds LMgR (L = [(DippNCMe)2CH]-, Dipp = 2,6-iPr2C6H3; R = nBu, CH3, C5H9) to 1 bar of CO in the presence of 10 mol% Ni(COD)2 (COD: 1,5-cyclooctadiene) selectively afforded the CO single-insertion product [LMg(CHO)C5H8], the dimerization product [(LMg)2(μ-C2O2)(CH3)2], and the linear trimerization product [(LMg)2(μ-C3O3)(nBu)2], respectively, depending on the R group. In addition, transition metal-stabilized carbene species resulted from CO activation were successfully isolated through stoichiometric control experiments. The profiles of CO trimerization and dimerization were further elucidated by density functional theory calculations, which confirmed the crucial roles of Mg/Ni cooperation and carbene species in the current reaction.