Preparation and molecular structures of some complexes containing C5 chains

Complexes containing a Co3 cluster linked to SiMe3, Au(PPh3), W(CO)3Cp and Fc groups by a C5 chain have been prepared by elimination of AuBr(PR3) (R=Ph, tol) in the reactions between Co3(μ3-CBr)(μ-dppm)(CO)7 and {(R3P)Au}CCCCX [X=SiMe3, W(CO)3Cp] or {(OC)7(μ-dppm)Co3}CCC{Au(PPh3)} and FcCCI (X=Fc). Subsequent auro-desilylation of the SiMe3 compound affords {(OC)7(μ-dppm)Co3}CCCCC{Au[P(tol)3]}. Single-crystal X-ray structures of the W(CO)3Cp, Au{P(tol)3} and Fc complexes are reported. The C5 chain shows little departure from a formal CCCCC fragment.Reactions between Co3(μ3-CBr)(μ-dppm)(CO)7 and XCCCCAu{P(tol)3} give {(OC)7(μ-dppm)Co3}CCCCCX [X=W(CO)3Cp, SiMe3] in which a five-carbon chain, formally a diynylcarbyne, links the Co3 cluster with the X fragment. A related multi-step sequence was used to make the analogous ferrocenyl derivative.