Alkynyl and poly-ynyl derivatives of carbon-tricobalt clusters

Abstract

A series of alkynyl-tricobalt carbonyl clusters, Co₃(μ₃-CnR)(μ-dppm)(CO)₇ [R = But, Ph, C₆H₄I, C₆H₄C≡CPh, 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(C≡CR)(PPh₃) or between Co₃{μ₃-CC≡CAu(PR₃)} (μ-dppm)(CO)₇ (R = Ph, tol) and IC≡CR′ (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-CC≡C)}₂C₆H₃X-5 (X = H, Br), 1,3,5-{(OC)₇(μ-dppm)Co₃(μ₃-CC≡C)}₃C₆H₃ and 1,1′-{(OC)₇(μ-dppm)Co₃ (μ₃-CC≡C)}₂Fc′ [Fc′ = Fe(η-C₅H₄-)₂]. The X-ray determined molecular structures of 12 of the complexes are reported.