Alkynyl and poly-ynyl derivatives of carbon-tricobalt clusters

A series of alkynyl-tricobalt carbonyl clusters, Co3(μ3-CnR)(μ-dppm)(CO)7 [R = But, Ph, C6H4I, C6H4Ctriple bond; length of mdashCPh, SiMe3, Fc, Au(PPh3)] containing three, five or seven carbons in the chain, have been prepared by elimination of phosphine–gold(I) halides in reactions between Co3(μ3-CBr)(μ-dppm)(CO)7 and Au(Ctriple bond; length of mdashCR)(PPh3) or between Co3{μ3-CCtriple bond; length of mdashCAu(PR3)} (μ-dppm)(CO)7 (R = Ph, tol) and ICtriple bond; length of mdashCR′ (R′ = SiMe3, Fc). The use of poly-substituted arenes or ferrocenes has enabled preparation of the complexes 1,4-{(OC)7(μ-dppm)Co3 (μ3-CCtriple bond; length of mdashC)}2C6H3X-5 (X = H, Br), 1,3,5-{(OC)7(μ-dppm)Co3(μ3-CCtriple bond; length of mdashC)}3C6H3 and 1,1′-{(OC)7(μ-dppm)Co3 (μ3-CCtriple bond; length of mdashC)}2Fc′ [Fc′ = Fe(η-C5H4-)2]. The X-ray determined molecular structures of 12 of the complexes are reported.