Solid-state supramolecular structure formed between the 1-(diaminomethylene)thiourea and mellitic acid

Abstract

The single crystals of hexakis(1-(diaminomethylene)thiouron-1-ium) benzene-1,2,3,4,5,6-hexacarboxylate (mellitate(6-)) tetrahydrate suitable for the X-ray analysis were grown using a solution growth technique at room temperature. The compound crystallises in centrosymmetric space group of the triclinic system. The conformation of six crystallographically independent 1-(diaminomethylene)thiouron-1-ium cations is not strictly planar, but twisted. Both planar arms of the cations are oppositely rotated by 6.1(1) ÷ 20.9(1)o around the CN bonds involving the central N atom. All of the carboxylate groups of mellitate(6-) anion are inclined to the plane of aromatic six-membered carbon ring by 43.0(1) ÷ 72.0(1)o. Oppositely charged components i.e. 1-(diaminomethylene)thiouron-1-ium cations and mellitate(6-) anion interact each other via NH⋯O hydrogen bonds forming hexakis(1-(diaminomethylene)thiouron-1-ium) mellitate units that further interact with the water molecules forming hexakis(1-(diaminomethylene)thiouron-1-ium) mellitate tetrahydrate supramolecular architecture. Hirshfeld surface and the analysis of 2D fingerprint plots are used for illustrate both qualitatively and quantitatively interactions between the units governing the supramolecular assemblies. The compound was also characterised by vibrational spectroscopy. The vibrational assignment have been supported by the isotopic frequency shift.