Polymorphism and DFT calculations of 1,4-bis(triisopropylsilyl)buta-1,3-diyne

• A new crystal polymorph is discovered for bis(triisopropylsilyl)buta-1,3-diyne.
• A DFT study is conducted for all rotamers in the same symmetry class.
• Correlations made between molecular structure, stability and crystal occurrence.

Two polymorph forms of 1,4-bis(triisopropylsilyl)buta-1,3-diyne were investigated by X-ray analysis. The polymorph grown from acetone solution crystallized in the monoclinic crystal system with one molecule in a general position of the asymmetric unit. A second polymorph grown from acetonitrile and ethanol solutions crystallized in the triclinic crystal system with a molecule located on an inversion center. The two polymorphs have slightly different molecular geometries and crystal packing motifs. The conformations found in these polymorphs were investigated and compared with five other rotamers as possible candidates for conformational polymorphs using DFT calculations.