Keywords: Alkynes / Boranes / Ferrocenes / NMR spectroscopy / Tin Ferrocenylethynyl(trimethyl)tin (1), bis(ferrocenylethynyl)dimethyltin (2), tetrakis(ferrocenylethynyl)tin (3), and chloro-(ferrocenylethynyl)dimethyltin (4) Sn NMR spectra were measured for 2 and 3, and the molecular structure of one of the modifications of 2 was determined by X-ray analysis. The reactivity of 1-4 towards triethylborane has been explored. 1,1-Organoboration takes place in all cases, and the reactions are stereoselective for 1 and 4 to give the alkenes 5 and 6, respectively, in which the stannyl and the boryl groups are in cis-positions at the C=C bond. In the case of 2, the final