3-Hexyne is the organic compound with the formula C2H5CCC2H5. This colorless liquid is the most common of the three isomeric hexynes. Together with 2-butyne and diphenylacetylene, it serves as a reference acetylenic ligand in organometallic chemistry. 3-Hexyne is useful because the 1H NMR signals for the methylene bridges convey stereochemical information in its octahedral complexes.