The hydrogen-bonded complex bis(tert-butylammonium) 2,6-dichlorophenolate 2,4-dichlorophenol-2,4-dichlorophenolate tetrahydrofuran disolvate containing a chiral R-5(3)(10) hydrogen-bonded ring as a supramolecular synthon

摘要

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 motif R-5(3)(10) was observed previously in a cocrystal of 2,4,6-trichlorophenol, 2,4-dichlorophenol and dicyclohexylamine. In the title solvated salt, 2C(4)H(12)N(+)center dot-C6H3Cl2O-center dot(C6H3Cl2O-center dot C6H4Cl2O)center dot 2C(4)H(8)O, five components, namely two tert-butylammonium cations, one 2,4-dichlorophenol molecule, one 2,4-dichlorophenolate anion and one 2,6-dichlorophenolate anion, are bound by N-H center dot center dot center dot O and O-H center dot center dot center dot O hydrogen bonds to form a hydrogen-bonded ring, with the graph-set motif R-5(3)(10), which is further associated with two pendant tetrahydrofuran molecules by N-H center dot center dot center dot 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 the c axis, and successive pairs of rings are associated with each other through C-H center dot center dot center dot pi interactions. Neighbouring helical columns are inversely related and, therefore, no chirality is sustained, in contrast to the previous case.