Structural and vibrational characterization of 1-(diaminomethylene)-thiouron-1-ium 4-aminobenzoate

Abstract

The single crystals of 1-(diaminomethylene)thiouron-1-ium 4-aminobenzoate, (C2H7N4S)-(NH2C6H4COO), (1) suitable for the X-ray analysis were grown using a solution growth technique room temperature. Recrystallization of 1 in heavy water (three-times) yield respective deuterated analogue, (C2D7N4S)(ND2C6H4COO), (1d). The X-ray single crystals analyses show that both, protiated and deuterated, compounds crystallize in the same crystal system with quite similar lattice parameters. The conformation of the 1-(diaminomethylene)thiouron-1-ium cation is not strictly planar, but slightly twisted. The 4-aminobenzoate(-) anion is also non-planar. The planar COO− group is inclined to the plane of aromatic ring by 5.2(2)o. In the crystal the oppositely charged units, i.e. 1-(diaminomethylene)thiouron-1-ium cation and 4-aminobenzoate anion interact via two of almost linear NH…O hydrogen bonds with a graph of R22(8), that are further interact each other forming three dimensional hydrogen-bonded network. Hirshfeld surface and the analysis of 2D fingerprint plots are illustrating both quantitatively and qualitatively interactions governing the supramolecular assemblies. The compound was also characterised by the FT-IR and Raman spectroscopy. The vibrational assignments have been supported by the isotopic frequency shift as well as by the DFT calculations.