Transition metal complexes of substituted alkynes. X. The formation of disubstituted cyclopentadienone complexes from terminal alkynes and (η-C5H5)Co(CO)2

Abstract

The reaction at 160� of dicarbonyl(η-cyclopentadienyl)cobalt with each of the terminal alkynes phenylacetylene, t-butylacetylene, propyne, and 3,3,3-trifluoropropyne has been studied. The reactions give p(disubstituted cyclopentadienone)-η-cyclopenta-dienylcobalt complexes as the major products; two or three isomers of each cyclo- pentadienonecobalt complex are formed. The arrangement of the substituents in each isomer has been assigned on the basis of electronic, infrared, nuclear magnetic resonance, and mass spectral data. Attempts to rationalize the distribution of isomers are based on considerations of electronic and steric effects.