Reaction of ethyl diazoacetate with Co3(CO)9(μ3-CCl): Isolation and X-ray structures of Co3(CO)9(μ3-CCO2Et), Co3(CO)9(μ3-CCH2CO2Et), and [Co3(CO)9(μ3-CCHCO2Et)

Abstract

The reaction between the tricobalt cluster Co3(CO)9(μ3-CCl) (1) and AlCl3, followed by treatment with ethyl diazoacetate, N2CHCO2Et, affords a complex mixture of products in low yields. Column chromatography has allowed the isolation of the four cluster compounds Co3(CO)9(μ3-CH) (2), Co3(CO)9(μ3-CCO2Et) (3), Co3(CO)9(μ3-CCH2CO2Et) (4), and [Co3(CO)9(μ3-CCHCO2Et)]2 (5). Clusters 4 and 5 are new and have been fully characterized in solution by IR and 1H NMR spectroscopy. The molecular structures of clusters 3–5 have also been determined by single-crystal X-ray diffraction analysis. Co3(CO)9(μ3-CCO2Et) crystallizes in the triclinic space group P $$\bar 1$$ , a = 8.8393(5), b = 14.727(1), c = 15.272(1) A, α = 93.361(6), β = 105.509(5)°, γ = 100.336(6)°, V = 1872.6(2) A3, Z = 4, and d calc = 1.823 g/cm3. Co3(CO)9(μ3-CCH2CO2Et) crystallizes in the monoclinic space group P21/n, a = 9.3806(7), b = 9.2617(8), c = 22.455(2) A, β = 94.483(7)°, V = 1944.9(3) A3, Z = 4, and d calc = 1.803 g/cm3. [Co3(CO)9(μ3-CCHCO2Et)]2 crystallizes in the monoclinic space group C2/c, a = 21.585(2), b = 8.7977(7), c = 20.784(1) A, β = 104.807(6)°, V = 3815.8(5) A3, Z = 4, and d calc = 1.835 g/cm3. Plausible pathways leading to the formation of clusters 2, 4, and 5 are discussed.