In the title compound, C6H10N2O2, the piperazine-2,3-dione ring adopts a half-chair conformation. In the crystal, the mol­ecules are linked by weak C—H⋯O hydrogen bonds, forming (010) sheets.

Modulation of the phenyl groups in N,N′-di­benzyl­ethyl­enedi­ammonium dichloride in P21/n allows for the formation of a network of strong N—H⋯Cl hydrogen bonds and C—H⋯Cl inter­actions and breaks C2/c symmetry.

The photoluminescent properties of the monoclinic and triclinic polymorphs in the solid state are strictly comparable, presumably because the spatial organization of both polymorphs is quite similar.

The structures of four polysulfinyl- and two polysul­fan­ylfer­ro­cenes were examined. Nonclassical C—H⋯X (X = O, S and C) hydrogen bonds have a large influence on most of the individual crystal structures, with different importance for the sulfinyl and sul­fan­yl com­pounds. Chalcogen O⋯O, S⋯S or S⋯O bonding is not significant, except for one com­pound, and π–ring inter­actions are important for only one com­pound.

The packing of the title hydrated mol­ecular salt features an unusual O—H⋯π inter­action.

A mononuclear cadmium(II) complex [CdLCl], where HL = 2-[bis­(pyridin-2-ylmeth­yl)amino]­ethane-1-thiol, was synthesized and characterized by single-crystal X-ray diffraction and Hirshfeld analysis.

The title compound, which was obtained by the reaction between 1,10-phenanthroline and phenyl­tin trichloride in methanol, exhibits intra­molecular inter­actions involving the chlorine and hydrogen atoms. Crystal cohesion is ensured by inter­molecular C—H⋯Cl hydrogen bonds, as well as Y—X⋯π and π-stacking inter­actions

The title mol­ecular salt was prepared by the reaction of sulfamethoxazole and H2SO4 in methanol and crystallized from methanol–ether–water. Protonation takes place at the nitro­gen atom of the primary amino group. In the crystal, N—H⋯O hydrogen bonds (water and methyl­sulfate anion) and inter­molecular N—H⋯N inter­actions involving the sulfonamide and isoxazole nitro­gen atoms, link the components into a tri-dimensional network, which also features face-to-face π–π inter­actions between the phenyl rings of adjacent mol­ecules.

The title compound, (C9H8NO)[CuCl3(C7H5NO4)]·2H2O, was synthesized by reacting CuII acetate, 8-hy­droxy­quinoline, and pyridine-2,6-di­carb­oxy­lic acid in dilute hydro­chloric acid in a 1:1:1 molar ratio. The Cu(II) atom exhibits a distorted octa­hedral geometry coordinated by the H2pydc ligand and chloride atoms. In the crystal structure, various hydrogen bonds and weak inter­actions lead to the formation of a three-dimensional network.