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The molecule of the title compound, C9H7NO, is nearly planar, with an r.m.s. deviation of 0.018 (7) Å. In the crystal structure, two molecules form an R²2(8) centrosymmetric dimer through N H⋯O hydrogen bonds. The three-dimensional packing is additionally stabilized through weak C—H⋯O interactions. [ABSTRACT FROM AUTHOR]

The title compound, C16H9NO4, also known as the 3-benzoylpyridinium betaine of squaric acid, exhibits a dipolar electronic ground-state structure with a positively charged pyridinium fragment and a negatively charged squarate moiety. In the molecule, the two aromatic rings are twisted by 56.03 (2)° relative to one another. The three-dimensional packing of the molecules is stabilized by C—H··O· short contacts. [ABSTRACT FROM AUTHOR]

The molecule of the title compound, C5H14NO4P, exists as a zwitterion rather than as [1-(hydroxyethyl­amino)propyl]­phospho­nic acid, with the N atom of the amino group protonated and the phospho­nic acid group negatively charged. In the crystal structure, the molecules are linked via extensive hydrogen bonding, forming layers parallel to (100). [ABSTRACT FROM AUTHOR]

The title compound, C6H12NO5P, was synthesized as an inter­mediate phase in a search for new N-(phosphono­methyl)glycine derivatives. The mol­ecules are held together by O—H⋯O hydrogen bonds, forming chains along the b axis in the crystal structure. The observed mol­ecular structure is compared with that calculated by the density functional theory method. [ABSTRACT FROM AUTHOR]

The crystal structures of four cyclo­alkane­spiro-4′-imidazolidine-2′,5′-dithiones, namely cyclo­pentane­spiro-4′-imidazolidine-2′,5′-dithione {systematic name: 1,3-diaza­spiro­[4.4]­nonane-2,4-dithione}, C7H10N2S2, cyclo­hexane­spiro-4′-imidazolidine-2′,5′-dithione {systematic name: 1,3-diaza­spiro­[4.5]decane-2,4-dithione}, C8H12N2S2, cyclo­heptane­spiro-4′-imidazolidine-2′,5′-dithione {systematic name: 1,3-diaza­spiro­[4.6]undecane-2,4-dithione}, C9H14N2S2, and cyclo­octane­spiro-4′-imidazolidine-2′,5′-dithione {systematic name: 1,3-di­aza­spiro­[4.7]dodecane-2,4-dithione}, C10H16N2S2, have been determined. The three-dimensional packing in all of the structures is based on closely similar chains, in which hydantoin moieties are linked through N—H⋯S hydrogen bonding. The size of the cyclo­alkane moiety influences the degree of its deformation. In the cyclo­octane compound, the cyclo­octane ring assumes both boat–chair and boat–boat conformations. [ABSTRACT FROM AUTHOR]

The title compound [systematic name: 1′-amino­cyclo­hexane­spiro-4′-imidazole-2′,5′(3′ H,4′ H)-dione], C8H13N3O2, has been synthesized and was found to crystallize in two different structures, both monoclinic and both with the same P21/ c space group. In the first structure, there are two mol­ecules in the asymmetric unit, one of which uses all of its hydrogen-bond donors and acceptors and forms undulating layers, while the other forms chains propagating perpendicular to the layers. In the second structure, there is only one independent mol­ecule and the packing is based on a chain structure mediated by hydrogen bonding between the hydantoin moieties and further grouped into hydro­philic layers separated by layers of the hydro­phobic cyclo­hex­yl groups. [ABSTRACT FROM AUTHOR]

In the title compound, C11H10N+·C4H5O6−·2H2O, hydrogen tartrate anions and water molecules are linked by strong O—H...O hydrogen bonds to form corrugated layers. The 4-phenylpyridinium cation decorates the layer from both sides, being hydrogen bonded to the water molecule only. The three-dimensional packing of the complex layers is accomplished by strong π–π interactions of 3.668 (2) Å between the centroids of the benzyl and pyridine rings related by the symmetry operator ( x −  , − y +  , − z). [ABSTRACT FROM AUTHOR]

In the title compound, 3,4-dioxo-2-(pyridinium-1-yl)cyclobut-1-enolate, C9H5NO3, molecules are connected three-dimensionally through nonclassical C—H...O and π–π interactions [3.220 (3) Å] between the oppositely charged squarate and pyridinium fragments. Classical hydrogen-bonding interactions are not observed. In the unit cell, only half an independent molecule is present and a twofold rotation axis passes through the pyridinium ring and the opposite CO group. [ABSTRACT FROM AUTHOR]

In the title compound, sodium 2-hydr­oxy-3,4-dioxocyclo­but-1-en-1-olate monohydrate, Na+·C4HO4−·H2O, the Na atom is six-coordinated by the O atoms from four hydrogensquarate anions and two water mol­ecules. The three-dimensional packing is stabilized by a system of hydrogen bonds. [ABSTRACT FROM AUTHOR]