The hydrogen-bonded complex bis(tert-butylammonium) 2,6-dichlorophenolate 2,4-dichlorophenol–2,4-dichlorophenolate tetrahydrofuran disolvate containing a chiralR53(10) hydrogen-bonded ring as a supramolecular synthon

Abstract

A fixed hydrogen-bonding motif with a high probability of occurring when appropriate functional groups are involved is described as a `supramolecular hydrogen-bonding synthon'. The identification of these synthons may enable the prediction of accurate crystal structures. The rare chiral hydrogen-bonding motifR53(10) was observed previously in a cocrystal of 2,4,6-trichlorophenol, 2,4-dichlorophenol and dicyclohexylamine. In the title solvated salt, 2C4H12N+·C6H3Cl2O−·(C6H3Cl2O−·C6H4Cl2O)·2C4H8O, five components, namely twotert-butylammonium cations, one 2,4-dichlorophenol molecule, one 2,4-dichlorophenolate anion and one 2,6-dichlorophenolate anion, are bound by N—H...O and O—H...O hydrogen bonds to form a hydrogen-bonded ring, with the graph-set motifR53(10), which is further associated with two pendant tetrahydrofuran molecules by N—H...O hydrogen bonds. The hydrogen-bonded ring has internal symmetry, with a twofold axis running through the centre of the 2,6-dichlorophenolate anion, and is isostructural with a previous and related structure formed from 2,4-dichlorophenol, dicyclohexylamine and 2,4,6-trichlorophenol. In the title crystal, helical columns are built by the alignment and twisting of the chiral hydrogen-bonded rings, along and across thecaxis, and successive pairs of rings are associated with each other through C—H...π interactions. Neighbouring helical columns are inversely related and, therefore, no chirality is sustained, in contrast to the previous case.