Catalytic Formation and Crystal Structure of Cyanoguanylurea H2NC(=O)NHC(NH2)NCN

The ion exchange reaction between ammonium cyanoureate NH4[H2NC(=O)NCN] and zinc chloride yielded single crystals of the urea derivative cyanoguanylurea H2NC(=O)NHC(NH2)NCN, which was obtained as a by-product alongside zinc cyanoureate and traces of ammonium chloride. It is assumed that owing to its Lewis and Brønsted acidity, the hydrated Zn2+ ion acts as a catalyst, promoting the degradation of the cyanoureate anion with subsequent formation of the title compound. The crystal structure was solved in the centrosymmetric space group P21/n (a = 476.7(1), b = 965.3(2), c = 1165.6(2) pm, β = 97.75(3)◦, V = 531.4(2) 106 pm3, Z = 4, T = 200 K). In the solid there are non-planar cyanoguanylurea molecules with a dicyandiamide-type C-N system, building up a layered structure with sparse interlayer contacts and significant hydrogen bonding within the layers.