Transition metal complexes of substituted alkynes. I. 3,3,3-Trifluoropropyne complexes of iron and cobalt

Abstract

Treatment of pentacarbonyliron with 3,3,3-trifluoropropyne, CF₃C≡CH, has given the stable complex tricarbonylbis(trifluoromethyl)cyclopentadi- enoneiron. Although a disubstituted cyclopentadienone can exist as three structural isomers, only one metal complex has been isolated. The interaction of octacarbonyldicobalt and 3,3,3-trifluoropropyne has given two metal complexes, one of which is a bridging alkyne complex of molecular stoicheiometry Co₂(CO)₆(CF₃CCH); the other, of formula Co₂(CO)₄(CF₃CCH)₃, is shown to have a metal-metal bridging unit which is formed by condensation of three alkyne groups. Infrared, nuclear magnetic resonance, and mass spectra of these complexes are given, and the structures of the compounds described.