Hydrogen-bonded linear thiourea hexads in tetra-n-butylammonium terephthalate inclusion compounds

Abstract

The co-crystallisation of thiourea (tu) with tetra-n-butylammonium terephthalate gave either [NBu₄]₂[C₆H₄(CO₂)₂-1,4]·6tu·2H₂O 1 or [NBu₄]₆[C₆H₄(CO₂)₂-1,4]₃·6tu·4H₂O 2, depending on the solvent and stoichiometry employed. Both compounds have structures containing hydrogen-bonded linear thiourea hexads, though these hexads are connected via additional hydrogen bonds into a three-dimensional network in 1 and a two-dimensional sheet structure in 2. The compound [NBu₄]Br·2tu 3, resulting from an impurity in one of the starting materials, has also been isolated and structurally characterised. An analysis of the Cambridge Structural Database has demonstrated that the flattened conformations observed for the NBu₄⁺ cations in these compounds are not atypical.