Hydrogen bonding in 1-carb­oxy­propanaminium nitrate

There are two crystallographically independent cations and two anions in the asymmetric unit of the title compound, C4H5NO2 +·NO3 −. In the crystal, the 1-carb­oxy­propanaminium cations and nitrate anions are linked to each other through strong N—H⋯O and O—H⋯O hydrogen bonds, forming a three-dimensional complex network. C—H⋯O inter­actions also occur

trans-Diaqua­bis­(dl-valinato-κ2 N,O)nickel(II)

In the title complex, [Ni(C5H9NO2)2(H2O)2], the NiII atom, located on a centre of inversion, is trans-coordinated by two O atoms and two N atoms from d-bidentate valine and l-bidentate valine ligands and two water O atoms in an octa­hedral geometry. In the crystal, the discrete mononuclear units are linked into a three-dimensional network via O—H⋯O and N—H⋯O hydrogen bonds. C—H⋯O inter­actions are also observed

Cytosinium hydrogen selenite

In the crystal structure of the title salt, C4H6N3O+·HSeO3−, systematic name 6-amino-2-methylidene-2,3-dihydropyrimidin-1-ium hydrogen selenite, the hydrogenselenite anions and the cytosinium cations are linked via N—H...O, N—H...Se, O—H...O, O—H··Se and C—H...O hydrogen bonds, forming a three-dimensional framework

A comparative study of two polymorphs of L-aspartic acid hydrochloride

International audienceTwo polymorphs of l-aspartic acid hydrochloride, C4H8NO4+center dot Cl-, were obtained from the same aqueous solution. Their crystal structures have been determined from single-crystal data collected at 100 K. The crystal structures revealed three-and two-dimensional hydrogen-bonding networks for the triclinic and orthorhombic polymorphs, respectively. The cations and anions are connected to one another via N-H center dot center dot center dot Cl and O-H center dot center dot center dot Cl interactions and form alternating cation-anion layer-like structures. The two polymorphs share common structural features; however, the conformations of the l-aspartate cations and the crystal packings are different. Furthermore, the molecular packing of the orthorhombic polymorph contains more interesting interactions which seems to be a favourable factor for more efficient charge transfer within the crystal

The structural properties of a noncentrosymmetric polymorph of 4-aminobenzoic acid

International audienceThe crystal structure of a polymorph of 4-aminobenzoic acid (PABA), C7H7NO2, at 100 K is noncentrosymmetric, as opposed to centrosymmetric in the structures of the other known polymorphs. The two crystallographically independent PABA molecules form pseudocentrosymmetric O-H center dot center dot center dot O hydrogen-bonded dimers that are further linked by N-H center dot center dot center dot O hydrogen bonds into a three-dimensional network. The benzene rings stack in the b direction. The CO2 moieties are bent out slightly from the benzene ring plane

Structural analysis and IR-spectroscopy of a new anilinium hydrogenselenite hybrid compound: A subtle structural phase transition

International audienceAn interesting structural behavior has been detected and characterized in a new anilinium based compound by single crystal X-ray diffraction measurements and infrared spectroscopy. The temperature dependent structural investigation reveals that the studied compound undergoes a subtle non-centrosymmetric to centrosymmetric structural phase transition. At room temperature the crystal structure is non-centrosymmetric and is characterized by an important disorder in the organic part where the independent aromatic rings are rotated around the C1-C4 and C7-C10 molecular axis by 52.06(6)degrees and 56.25(4)degrees respectively. By decreasing the temperature to 100 K the organic cation is less disordered and the rotation angle of the aromatic rings changes to 54.73(2)degrees. As a consequence, the low temperature structure becomes centrosymmetric. The infrared spectra recorded on cooling and heating the sample in the temperature range of 300-9 K support this analysis. The ammonium group (NH3) is significantly affected by the temperature change. This effect results, when cooling the sample below 140 K, in the appearance of a new vibrational band corresponding to the (NH3)-wagging modes at 705 cm(-1). The phenomenon is completely reversible and the new vibrational band disappears upon heating the sample above 140 K. Moreover, the m(C-N)-stretching and the (NH3)-scissoring modes are also affected by the temperature variation as can be seen in the spectral ranges of 1250-1400 cm(-1) and 1610-1635 cm(-1) respectively. The spectroscopic results are complementary to the structural analysis and indicate that the structural phase transition is correlated with the molecular rotation of the aromatic moieties around the C1-C4 axis that affect the different vibrational modes of the ammonium group

A structural comparative study of charge transfer compounds: Synthesis, crystal structure, IR, Raman-spectroscopy, DFT computation and hirshfeld surface analysis

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