The crystals of a new melaminium salt, bis(2,4,6-triamino-1,3,5-triazin-1-ium) sulfate dihydrate, 2C3H7N6+*SO4(2-)*2H2O, are built up from monoprotonated melaminium(1+) residues, sulfate(2-) anions and water molecules. The SO4(2-) ion has a slightly distorted tetrahedral geometry. The melaminium residues are interconnected by N-H.N hydrogen bonds, forming chains. The chains of melaminium residues develop a three-dimensional network through multiple donor-acceptor hydrogen-bond interactions with sulfate anions and water molecules.

The reaction of 4-iodobenzenesulfonamide or 4-fluorobenzenesulfonamide with CS 2 and KOH in dimethylformamide yielded the potassium N-R-sulfonyldithiocarbimates, K 2 (RSO 2 N@CS 2) [R = 4-IC 6 H 4 (1) and 4-FC 6 H 4 (2)]. These salts reacted with K 2 [PtCl 4 ] in water/methanol to yield complex anions bis(N-R-sulfonyldithiocarbimato)platinate(II), which were isolated as their tetrabutylammonium salts, (Bu 4 N) 2 [Pt(RSO 2 N@CS 2) 2 ] [R = 4-IC 6 H 4 (3) and 4-FC 6 H 4 (4)]. The structures of 2-4 were determined by X-ray crystallography. The Pt 2+ in both complexes 3 and 4 lies at the inversion centre and the PtS 4 moiety has a distorted square-planar configuration. The compounds were also characterized by IR, 1 H NMR and 13 C NMR spectroscopies, and elemental analyses. The molar conductance data are consistent with the fact that 3 and 4 are dianionic complexes.

The crystals of a new melaminium salt, 2,4,6-triamino-1,3,5-triazin-1-ium chloride hemihydrate, C(3)H(7)N(6)(+).Cl(-).0.5H(2)O, are built up from single-protonated melaminium residues, chloride anions and water molecules. The protonated melaminium cations lie on a twofold axis, while the chloride anions and water molecule lie on the m plane. The melaminium residues are interconnected by N-H...N hydrogen bonds, forming chains parallel to the (001) plane. The chains of melaminium residues form a three-dimensional network through hydrogen-bond interactions with chloride anions and water molecules.

The crystals of the new melaminium salt, 2,4,6-triamino-1,3,5-triazin-1-ium hydrogenphthalate, C3H7N6+.C8H5O4-, are built up from single protonated melaminium residues and single dissociated hydrogenphthalate(1-) anions. The protonated melaminium ring is almost planar. The best plane through the non-dissociated carboxyl group (COOH) of the hydrogenphthalate(1-) anion is inclined at an angle of 16.4 (2) degrees to the plane of the six-membered hydrogenphthalate ring, while the plane of the ionized COO- group is roughly perpendicular [84.2 (2) degrees ] to this plane. A combination of ionic and donor-acceptor hydrogen-bond interactions linking together the melaminium and hydrogenphthalate residues forms a three-dimensional network.

Two crystals containing melamine (M), melaminium (MH +), and aromatic carboxylic acids are synthesized and characterized by single-crystal X-ray diffraction analysis: melamine-melaminium 3,4,5-trihydroxybenzoate (THB À) dihydrate (1), and melamine-melaminium 2-acetylbenzoate (AB À) dihydrate (2). In the crystal structures protonated (MH +) and non-protonated melamine (M) molecules are interconnected via NAHÁÁÁN hydrogen bonds into a planar dimer in (1) and one-dimensional polymer in (2). The NAHÁÁÁO hydrogen bonding interaction between the protonated nitrogen atom of MH + and the carboxylate oxygen atom of the corresponding anion is observed in both structures. However, only in (1) it results in an almost planar ionic unit (THB À MH +) where additional p-p interactions between the anions appear, that are missing in (2). The water molecules act as donor and as acceptor of hydrogen bonds linking the substructures observed in the (1) and (2) crystals into 3D supramolecular networks.