CeCl3/n‐BuLi: Unraveling Imamoto's Organocerium Reagent

CeCl3(thf) reacts at low temperatures with MeLi, t‐BuLi, and n‐BuLi to isolable organocerium complexes. Solvent‐dependent extensive n‐BuLi dissociation is revealed by 7Li NMR spectroscopy, suggesting “Ce(n‐Bu)3(thf)x” or solvent‐separated ion pairs like “[Li(thf)4][Ce(n‐Bu)4(thf)y]” as the dominant species of the Imamoto reagent. The stability of complexes Li3Ln(n‐Bu)6(thf)4 increases markedly with decreasing LnIII size. Closer inspection of the solution behavior of crystalline Li3Lu(n‐Bu)6(thf)4 and mixtures of LuCl3(thf)2/n‐BuLi in THF indicates occurring n‐BuLi dissociation only at molar ratios of