<p>1,4-Diethynyl-2,3,5,6-tetramethylbenzene crystallizes in the orthorhombic space group <i>Cmca</i> and the structure of features weak <i>sp-</i>C-H···π interactions. The 1:1 cocrystal formed between 1,4-diethynyl-2,3,5,6-tetramethylbenzene and 1,4-diaza-bicyclo[2.2.2]octane crystallizes in the triclinic space group <i>P</i>-1, while the cocrystal formed between 1,4-diethynyl-2,3,5,6-tetramethylbenzene and 4,4’-bipyridine crystallizes in the monoclinic space group <i>P</i>2<sub>1</sub>. Both cocrystals feature <i>sp-</i>C-H···N hydrogen bonds between the components. Analysis of the Hirschfeld surface within the cocrystals confirm that the C-H—N hydrogen bond corresponds to the closest atom-to-atom contact in the cocrystals. Indeed, the C-H—N separation range in the cocrystals ranges from 2.32 to 2.47 Å, corresponding to 84–90% of the sum of the van der Waals radii. Calculation of the intermolecular interaction energies within each crystal structure reveal that π-stacking interactions dominate even though the aromatic molecules are significantly offset. The C-H—N interaction although weaker than the π-stacking interactions should be considered as a major driving force for the formation of these cocrystals.</p> Graphical abstract <p></p>

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Evaluating the role of sp-C-HN hydrogen bonds in the structure of cocrystals formed between 1,4-diethynyl-2,3,5,6-tetramethylbenzene and each of 1,4-diaza-bicyclo[2.2.2]octane and 4,4’-dipyridine

  • Eric Bosch

摘要

1,4-Diethynyl-2,3,5,6-tetramethylbenzene crystallizes in the orthorhombic space group Cmca and the structure of features weak sp-C-H···π interactions. The 1:1 cocrystal formed between 1,4-diethynyl-2,3,5,6-tetramethylbenzene and 1,4-diaza-bicyclo[2.2.2]octane crystallizes in the triclinic space group P-1, while the cocrystal formed between 1,4-diethynyl-2,3,5,6-tetramethylbenzene and 4,4’-bipyridine crystallizes in the monoclinic space group P21. Both cocrystals feature sp-C-H···N hydrogen bonds between the components. Analysis of the Hirschfeld surface within the cocrystals confirm that the C-H—N hydrogen bond corresponds to the closest atom-to-atom contact in the cocrystals. Indeed, the C-H—N separation range in the cocrystals ranges from 2.32 to 2.47 Å, corresponding to 84–90% of the sum of the van der Waals radii. Calculation of the intermolecular interaction energies within each crystal structure reveal that π-stacking interactions dominate even though the aromatic molecules are significantly offset. The C-H—N interaction although weaker than the π-stacking interactions should be considered as a major driving force for the formation of these cocrystals.

Graphical abstract