Crystal engineering in the gem-alkynol family; synthon repetitivity and topological similarity in diphenylethynylmethanols: structures that lack O-­H⋯O hydrogen bonds

• Published in: Acta crystallographica. Section B, Structural science Structural science, 2000-12, Vol.56 (6), p.1071-1079
• Main Authors: Bilton, Clair, Howard, Judith A. K., Madhavi, N. N. L., Nangia, Ashwini, Desiraju, Gautam R., Allen, Frank H., Wilson, Chick C.
• Format: Article
• Language: English
• Subjects: gem-Alkynol; Synthon repetitivity; Topological similarity
• ISSN: 0108-7681; 1600-5740
• DOI: 10.1107/S010876810001154X

The structures of four para‐substituted derivatives of diphenylethynylmethanol have been determined [ditolylethynylmethanol, di(4‐chlorophenyl)ethynylmethanol, di(4‐bromophenyl)ethynylmethanol and bis(4,4′‐biphenylyl)ethynylmethanol]. The dimethyl, dichloro, dibromo and diphenyl compounds have been analysed using X‐ray diffraction at 150 K, and the dichloro compound has also been studied using neutron diffraction at 150 K. In common with the parent diphenylethynylmethanol [Garcia, Ramos, ­Rodriguez & Fronczek (1995). Acta Cryst. C51, 2674–2676], all four derivatives fail to form the expected strong O—H⋯O hydrogen bonds due to steric hindrance. Instead, the supramolecular structural organization in this family of gem‐alkynols is mediated by a variety of weaker interactions. The two most acidic protons, O—H and C[triple‐bond]C—H, participate in weak hydrogen bonds to π‐acceptors, forming synthons that stabilize all five structures. These primary interactions are reinforced by a variety of other weak hydrogen bonds involving C—H donors and the hydroxy‐O as an acceptor, and by halogen⋯halogen interactions in the dichloro and dibromo compounds.