The chloride,bromide and iodide salts of 1‐(diaminomethylene)thiouron‐1‐ium

Crystals of 1‐(diaminomethylene)thiouron‐1‐ium chloride, C₂H₇N₄S⁺·Cl^?, 1‐(diaminomethylene)thiouron‐1‐ium bromide, C₂H₇N₄S⁺·Br^?, and 1‐(diaminomethylene)thiouron‐1‐ium iodide, C₂H₇N₄S⁺·I^?, are built up from the nonplanar 1‐(diaminomethylene)thiouron‐1‐ium cation and the respective halogenide anion. The conformation of the 1‐(diaminomethylene)thiouron‐1‐ium cation in each case is twisted. Both arms of the cation are planar and rotated in opposite directions around the C—N bonds involving the central N atom. The dihedral angles describing the twisted conformation are 22.9 (1), 15.2 (1) and 4.2 (1)° in the chloride, bromide and iodide salts, respectively. Ionic and extensive hydrogen‐bonding interactions join oppositely charged units into a supramolecular network. The aim of the investigation is to study the influence of the size of the ionic radii of the Cl^?, Br^? and I^? ions on the dimensionality of the hydrogen‐bonding network of the 1‐(diaminomethylene)thiouron‐1‐ium cation. The 1‐(diaminomethylene)thiouron‐1‐ium system should be of use in crystal engineering to form multidimensional networks.