Reactions of electron-deficient benzoquinoline triosmium cluster [(μ-H)Os₃(CO)₉(μ₃-η²-C₁₃H₈N)] with diazomethane

Abstract

Treatment of the electron-deficient benzoquinoline triosmium cluster [(μ-H)Os₃(CO)₉(μ₃-η²-C₁₃H₈N)] 1 with excess CH₂N₂ at 0 to 25ºC leads to the formation of [(μ-H)₂Os₃(CO)₉(μ₃-η²-C₁₃H₈N)}] 2 in 85% yield. Compound 2 is formed by insertion and subsequent C-H oxidative addition of a CH2 moiety into the ring C(8)-Os bond. Heating 2 at 98ºC furnishes three new compounds [(μ-H)Os₃(CO)₉(μ₃-η²-C₁₃H₈N)] 3, [(μ-H)Os₃(CO)₉(μ₃-η²-C₁₃H₈N)}] 4, and [(μ-H)₂Os₃(CO)₈(μ₃-η²-C₁₃H₈N)}] 5 in 18%, 23% and 8% yields, respectively. The formation of compounds 3 and 4 involves activation of the methylidene C-H bond. Compound 5 is most probably formed from 4 via exchange of a bridging hydride with a chloride. The trihydride compound 3 reacts with CCl₄ at 77C to give the dihydrido chloro-compound 5 in 44% yield. Thermolysis of 2 in the presence of H₂ at 1 atm at 80ºC gives 3 in 75% yield. All the new compounds have been characterized on the basis of elemental analyses, IR, NMR and mass spectroscopic data.