AbstractIn the crystal structure of the title compound at 98 K the dimethylamino group has pyramidal geometry. The nitrogenlone pair is not directed towards the triple bond; instead, one NCH3bond lies almost in the plane of the disubstituted ring, directed away from the triple bond, while the other NCH3bond and the lone pair are directed to opposite sides of the plane, nearer to the acetylene. There is a remarkably short intramolecular contact (2.39 Å) between a methyl H‐ and an acetylenic C‐atom. TheTaftσIparameter of the arylethynyl substituent appears to be similar to that of a carboxylic ester, judging from the bond‐angle deformation at the