The crystal structures of two non-metal tricyanomelaminates:: Diammonium tricyanomelaminate dihydrate [NH4]2[C6N9H] • 2 H2O and dimelaminium tricyanomelaminate melamine dihydrate [C3N6H7]2[C6N9H] • C3N6H6 • 2 H2O

Diammonium tricyanomelaminate dihydrate [NH4](2)[C6N9H] center dot 2 H2O (1) and dimelaminium tricyanomelaminate melamine dihydrate [C3N6H7](2)[C6N9H] center dot C3N6H6 center dot 2 H2O (2) were obtained by metathesis reactions from Na-3[C6N9] in aqueous solution and characterized by single-crystal X-ray diffraction and N-15 solid-state NMR spectroscopy (1). Both salts contain mono-protonated tricyanomelaminate (TCM) anions and crystallize as dihydrates. Considering charge balance requirements, the crystal structure of I (C2/c, a = 3181.8(6) pm, b = 360.01(7) pm, c = 2190.4(4) pm, beta = 112.39(3)degrees, V = 2319.9(8) 10(6). pm(3)) can best be described by assuming a random distribution of an ammonium ion - crystal water pair over two energetically similar sites. Apart from two melaminium cations, 2 (P2(1)/c, a = 674.7(5) pm, b = 1123.6(5) pm, e = 3400.2(5) pm, beta = 95.398(5), V = 2566(2) 10(6) pm(3)) contains one neutral melamine per formula unit acting as an additional "solvent" molecule and yielding a donor-acceptor type of pi-stacking interaction.