Formation of a cluster-substituted cyclopentadienone from PhC2CCo3(CO)9. Crystal structure of Ph2C4C(O)2

Article abstract of DOI:10.1016/0022-328X(90)87182-D

The cluster-substituted alkyne PhC<*>CCCo3(CO)9 (1), obtained by a coupling reaction between BrCCo3(CO)9 and PhC<*>CH, rearranges to give the cyclopentadienone Ph2C4C(O)2 (2).Alkyne 1 with Co2(CO)8 gives PhC2CCo3(CO)9 (3).Compound 2 was characterised by X-ray crystallography at 123 K.The structure is that of a symmetrically substituted cyclopentadienone with tricobaltcarbon cluster moieties substituted α to the carbonyl group and phenyl substituents in the β positions.Various findings suggest that the formation of 2 does not proceed via a meta llacycle.Electrochemical data shows that the clusters and the cyclopentadienone ring act as independent redox centres, indicating that there is no contiguous ?-interaction.