Structural and spectroscopic characterization of bis[1-(diaminomethylene)thiouron-1-ium] naphthalene-1,5-disulfonate

Single crystals of bis[1-(diaminomethylene)thiouron-1-ium] naphthalene-1,5-disulfonate (1) are grown using growth solution technique. The compound crystallizes in the centrosymmetric C2/c space group of the monoclinic system with four molecules per unit cell. The arrangement of oppositely charged units, i.e. 1-(diaminomethylene)thiouron-1-ium cations and naphthalene-1,5-disulfonate anions in the crystal is mainly determined by the ionic and the NH⋯O hydrogen bonding interactions. Hirshfeld surface and the analysis of 2D fingerprint plots are illustrating both qualitatively and quantitatively interactions governing the supramolecular arrangement. The compound was also characterized by FT-IR and Raman spectroscopies. The vibrational assignment of the characteristic bands of the functional groups have been supported by the isotopic frequency shift.