Reductive coupling of CO with magnesium anthracene complexes: formation of magnesium enediolates

Abstract

Two β-diketiminato-magnesium anthracene complexes, [{(^ArNacnac)Mg}₂(μ-C₁₄H₁₀)] (^ArNacnac = [HC(MeCNAr)₂]⁻, Ar = mesityl (Mes) or 2,6-diethylphenyl (Dep)) react with 1 atm. CO at room temperature to give tetra-magnesium enediolate complexes [{(^ArNacnac)Mg}₄(O₂C₁₆H₁₀)₂] via coupling of two molecules of CO with the anthracenediyl fragment. Similarly, reaction of magnesium anthracene, [Mg(THF)₃(C₁₄H₁₀)], with CO afforded a low isolated yield of a tetra-magnesium complex bearing both dianthraceneylenediolate and dibenzocyclohepteneolateyl ligands. The presented reactions represent very rare examples of magnesium alkyl carbonylations that occur under mild conditions, and in the absence of catalysts.