Hydrogen-bonding network in the crystal of bis[1-(diaminomethylene)thiouron-1-ium] oxalate.

The single crystals of bis[1-(diaminomethylene)thiouron-1-ium] oxalate were grown using a solution growth technique. The compound crystallises in the centrosymmetric C2/c space group of the monoclinic system. The conformation of the 1-(diaminomethylene)thiouron-1-ium cation is not strictly planar, but twisted. Both arms of the cation are oppositely rotated by 5.0(1)_ around the C?N bonds involving the central N atom. The centrosymmetric oxalate(2-) anion is planar. The arrangement of oppositely charged components, i.e. 1-(diaminomethylene)thiouron-1-ium cations and oxalate(2-) anions in the crystal is mainly determined by ionic and hydrogen bonding interactions forming three-dimensional network. The compound was also characterised by the FT-IR and Raman spectroscopy. The characteristic bands of the NH2, C=S and COO_ groups as well as of C?N?C, N?C?N and C?COO skeletal groups are discussed