AbstractThe reaction between 2,4‐dibromothiophene and trimethylsilylacetylene (TMSA) in the presence of Pd(PPh3)4, CuI and triethylamine gave rise to the formation of 2,4‐bis(trimethylsilylethynyl)thiophene (2,4T) and 4‐bromo‐2‐(trimethylsilylethynyl)thiophene (2,4T′). Complexes 1, 2, 3 or 1′ were obtained by direct reaction between Co2(CO)8 and 2,4T or 2,4T′, respectively. (Diphenylphosphanyl)methane‐substituted alkyne carbonyl complexes 4, 5, 6 and 2′ were prepared by substitution reaction of carbonyl ligands in the presence of Me3NO at the Co2(CO)6 units of 1, 2, 3 and 1′, respectively. Desilylation of the non‐metallated and metallated alkynes in 4, 5 and 6 occurred on treatment with KOH or tetrabutylammonium fluoride to give 7, 8 and 9. Crystals of 2′ suitable for single‐crystal X‐ray diffraction were grown, and the molecular structure of this compound is discussed. A comparative electrochemical study of these complexes in relation to analogous derivatives obtained from the organic ligand 2,5‐bis(trimethylsilylethynyl)thiophene (2,5T) is reported.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)