Impact of sulfur substituents on the C-H center dot center dot center dot O interaction of terminal alkynes in crystal engineering

Investigation of the intermolecular interactions in the solid state of compounds containing terminal alkynes and sulfur substituents at sulfide, sulfoxide and sulfone levels is described. As the acidity of the hydrogens a to the sulfur substituent increases, these hydrogens compete effectively with the terminal alkyne as hydrogen bond donors in the solid state structure; this effect can be blocked through substitution at this position, resulting in the hydrogen bond switching back to the terminal alkyne. The impact of the chirality of the sulfoxide on the solid state structure is also highlighted.