Alain Lautié

N-H..S hydrogen bonds

Abstract Infrared spectra of some compounds containing weak and medium-strong NH..S hydrogen bonds have been investigated. Spectroscopic and structural data have been correlated and compared with those obtained for NH..O and NH..N systems. At the same strength, the N..S distance is 0.51 and 0.36 A longer than the corresponding N..O and N..N distances, respectively.

Etude par spectrométrie infrarouge et Raman de la pyrimidone-2 et de son chlorhydrate (chlorure d'oxo-2 pyrimidinium)

Abstract The i.r. and Raman spectra of crystalline 2-pyrimidone, its hydrochloride and corresponding N -deuterated derivatives have been investigated between 4000 and 200 cm − . Aqueous solutions were also examined. An assignment for all intramolecular fundamentals is given. Effects of the protonation on the C=O group and on the ring are discussed as well as strength and characteristics of the hydrogen bonds NH … O and NH … Cl − .

Etude vibrationnelle de la phase II des hydrogénodisulfates de triammonium, (NH4)3H(SO4)2 et (ND4)3D(SO4)2

Abstract The i.r. and Raman spectra of room temperature phase (phase II) of (NH 4 ) 3 H(SO 4 ) 2 and (ND 4 ) 3 D(SO 4 ) 2 as polycrystalline samples and single crystals have been investigated between 4000 and 30 cm −1 . An assignment of internal and external modes is given in terms of group frequencies and symmetry types. This crystal contains non-centrosymmetric dimers (SO 4 HSO 4 ) 3− where sulphate ions are associated by strong asymmetric OH … O hydrogen bonds; they are characterized by two strong Raman bands at 1078 and 966 cm −1 , and a νOH frequency at about 1250 cm −1 . The acidic proton is statistically disordered around the crystallographic symmetry centre while all of the NH + 4 ions show an important dynamical orientational disorder.

Spectres de vibration de la 2-pyridinethione, de la 3-pyridazine-thione et du 2,4-dithiouracile

Abstract The i.r. and Raman spectra of polycrystalline 2-pyridinethione, 3-pyridazinethione, 2,4-dithiouracile and corresponding N -deuterated derivatives have been investigated in 4000-40 cm −1 range. Solutions in various solvents were also examined. An assignment for all intramolecular fundamentals is given. Only the “thio” form was observed even in apolar solvents. A metastable solid phase has been shown-up for the deuterated 2,4-dithiouracile. In these compounds, the strength of NH ⋯ S hydrogen bonds are similar to NH ⋯ O interaction of corresponding “oxo” molecules and characterised by νNH frequencies about 2900 cm −1 .

Spectres de vibration de pigments rouges de la famille des quinacridones

Abstract The i.r. and Raman spectra of various crystalline phases of the trans linear quinacridone and some methylated and chlorinated derivatives have been investigated between 4000 and 200 cm−1. Each of these pigments has been characterized spectroscopically and an assignment for intramolecular fundamentals is given in terms of group frequencies. The strength and length of NH ⋯ O hydrogen bonds have been assessed from the vNH frequency and correlated with the pigment colour which is principally determined by intermolecular interactions rather than by the substituent hypso(batho)chromic effect. The NH ⋯ O distance increases from 2.87 A for the red compounds to 2.93 A for the purple ones.

Etude de l'acridinone par spectrometries i.r. et Raman: C13H9NO et C13H8DNO

Abstract The i.r. and Raman spectra of polycrystalline acridinone and N -deuterated derivatives have been investigated between 4000 and 200 cm −1 ; solutions in various solvents were also examined. An assignment for intramolecular fundamentals is given in terms of group frequencies and symmetry type. The strength and characteristics of the NH⋯O hydrogen bonds are discussed as well as the crystal structure.

Etude par spectrometrie infrarouge et Raman de la triméthyl-4,5,6 pyrimidone-2 et de son chlorhydrate. Complexation par les halogenures de potassium

Abstract The i.r. Raman spectra of crystalline 4,5,6-trimethyl 2-pyrimidone and seven deuterated derivatives have been investigated between 4000 and 180 cm −1 . Aqueous and CHCl 3 solutions were also examined. An assignment for intramolecular fundamentals is given, as well as a distinction between the most characteristic of each methyl group. The methylation and protonation effects are discussed. Furthermore, a 1 1 adduct of this pyrimidone and potassium halides is observed and characterized; it contains a strong NH…X − hydrogen bond.

Polymorphism in 4-methyl-1,2,4-triazolethione

Raman and infrared spectra of 4-methyl-1,2,4-triazolethione showed that two crystalline phases, one stable and the other metastable, can be obtained from various crystallization processes. The metastable phase transforms into the stable phase at 395 K by an irreversible first-order phase transition. The two phases were characterized spectroscopically and structural properties are discussed. Copyright

Spectres de vibration et structure de l'acide pyrrolecarboxylique-2 cristallisé

Abstract The i.r. spectra of solid pyrrole-2-carboxylic acid C 4 H 3 NHCOOH and C 4 H 3 NDCOOD have been investigated between 4000 and 200 cm −1 . An assignment for all 30 intramolecular fundamentals is given and their frequencies compared to those of pyrrole. Molecular properties, crystal structure and OH … O and NH … O hydrogen bonds of this compound are discussed.

Caractérisation et approche structurale de verres du systeme La2O3–MgO–B2O3

In this paper, a vitreous domain of the ternary system: xLa2O3–yMgO–zB2O3 characterised by X-ray diffraction is shown. Structural approach using vibrational spectroscopy and optical probe is realized for some of these glasses and compared to crystalline LaMgB5O10...