Conversion of C≡C to CO in alkynyl-metal complexes: oxidation of carbon chains capped by carbon-tricobalt clusters

Abstract

Treatment of Co₃(μ₃-CC≡CR)(μ-dppm)(CO)₇ with O₂ (air) in the presence of [FcH]PF₆ afforded Co₃{μ₃-CC(O)R}(μ-dppm)(CO)₇ by the formal conversion –C≡C– + O–O → >C–O + C≡O. In this way, complexes with R = Ph, Fc, and W(CO)₃Cp, bis-clusters {Co₃(μ-dppm)(CO)₇}₂{μ₃:μ₃-[≡C(O)(C≡C)C≡]}, {Co₃(μ-dppm)(CO)₇}₂{μ₃:μ₃-[≡C(O)(C≡C)xC(O)C≡]} (x = 1, 2), and {Co₃(μ-dppm)(CO)₇}₂{μ₃:μ₃-[≡CC(O)C≡CC₆H4C≡CC(O)C≡]}, and heterometallic bis-clusters {Co₃(μ-dppm)(CO)₇}{μ₃:μ₃-[≡CC(O)C≡CC≡]}{M₃(μ-H)₃(CO)₉} (M = Ru, Os) have been prepared. Single-crystal XRD structure determinations of several products are reported together with that of precursor {Co₃(μ-dppm)(CO)₇}₂{μ₃:μ₃-[≡C(C≡C)₂C₆H₄(C≡C)₂C≡]}.