Hydrogen-bonded networks in crystals of 1-(diaminomethylene)thiouron-1-ium perchlorate, hydrogen sulfate, dihydrogen phosphate and dihydrogen arsenate.

Crystals of the title compounds, namely 1-(diaminomethylene)thiouron-1-ium perchlorate, C2H7N4S+.ClO4-, 1-(diaminomethylene)thiouron-1-ium hydrogen sulfate, C2H7N4S+.HSO4-, 1-(diaminomethylene)thiouron-1-ium dihydrogen phosphate, C2H7N4S+.H2PO4-, and its isomorphic relative 1-(diaminomethylene)thiouron-1-ium dihydrogen arsenate, C2H7N4S+.H2AsO4-, are built up from a nonplanar 1-(diaminomethylene)thiouron-1-ium cation and the respective anion linked together via N-H...O hydrogen bonds. Both arms of the cation are planar, but they are twisted with respect to one another around the central N atom. Ionic and extensive hydrogen-bonding interactions join oppositely charged units into layers in the perchlorate, double layers in the hydrogen sulfate, and a three-dimensional network in the dihydrogen phosphate and dihydrogen arsenate salts. This work demonstrates the usefulness of 1-(diaminomethylene)thiourea in crystal engineering for the formation of supramolecular networks with acids.