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

The i.r. spectra of solid pyrrole-2-carboxylic acid C₄H₃NHCOOH and C₄H₃NDCOOD 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.     

Spectres de vibration de monocristaux de paratoluidine à la température de l'hélium liquide

A comparative study is made of i.r. and Raman spectra of p-toluidine rhombic single crystals in the 0–200 cm⁻¹ range, at liquid helium temperature. No evidence of a phase transition up to room temperature has been found     

Spectres vibrationnels et champ de force de divers composés de formule A2B2O7 et A2B2O6 de structure pyrochlore

The i.r. and Raman spectra of compounds Cd₂^IIB₂^VO₇ and A₂^IIB₂^VO₆ (A  Ag, Tl; B  Ta, Nb, Sb) belonging to the pyrochlore structure were studied. A normal coordinate analysis permitted us to calculate and to compare their force field (and also for Na₂Sb₂O₆) which is discussed.     

Microdosages des composés caractéristiques de la fermentation butanediolique

Compounds characteristic of the butanediol fermentation are 2–3 butanediol, acetoin and diacetyl; tlie determination of each of these compounds is based on a determination of dimethylglyoxime by nickel (II) (as in the classical methods, which are time-consuming and not very sensitive). The method now deseribed uses the soluble red complex given by dimethylglyoxime with niekel (IV). By this means 4 colorimetric methods have been established which, respcetively, permit: 1. The determination in 5 minutes, to about 1 %, of 120 to 600 μg, of dimethylglyoxime in a 10 ml sample. 2. The determination in 30 minutes, to about 1 %, of 90 to 450 μg, of diacetylin a sample of 10, 50 or 100 ml. 3. The determination in 50 minutes, to about 1 %, of 90 to 450 μg, of acetoin in a sample of 10, 50 or 100 ml. 4. The determination in 70 minutes, to about 3 %, of 100–500 μg, of butanediol in a 10 ml sample. These methods, based on specific reactions of the substances being determined, (in contradistinction to the numerous methods recently proposed for the determination of butanediol) are applicable even when the substances are accompanied by 1000 times their weight of glucose, glycerol, etc.     

Propriétés physico-chimiques de composés à caractère aromatique IX

Résumé Le spectre U.V. de solutions contenant un dérivé N-méthylé aza-aromatique en présence d'un hydrocarbure polycyclique présente une bande supplémentaire, qui est attribuée à un complexe de transfert de charge. Cette hypothèse est étayée par la comparaison des énergies de transition avec celles observées pour les transferts de charge entre les ions I^– et ces mêmes dérivés N-méthylés.Les positions des bandes de transfert de charge de l'iodure de pyridinium sont interprétées sur la base de considérations théoriques.

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The U.V. spectra of solutions of N-methylated monoaza-aromatic compounds show new absorption bands when polycyclic aromatic hydrocarbons are added. This is attributed to the formation of charge transfer complexes. This hypothesis is supported by the comparison of these spectra with those obtained from the interaction of I^– with the same methylated monoazaaromatic compounds.An attempt to interpret the positions of the charge transfer bands in the spectra of pyridinium iodide and N-methylpyridinium iodide, based on theoretical data, is given.

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Zusammenfassung Die UV-Spektren von Lösungen eines N-Methyl-aza-aromaten in Gegenwart eines polycyclischen Kohlenwasserstoffes zeigen eine zusätzliche Bande, die einem Elektronenacceptordonator-Komplex zuzuordnen ist. Diese Hypothese wird durch den Vergleich des Spektrums mit demjenigen des analogen Jod-Komplexes gestützt.Außerdem wird die Lage der Charge-Transfer-Bande des Pyridiniumjodids durch theoretische Überlegungen erklärt.

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Pour I et VIII voir respectivement: a) Coppens, G., et J. Nasielski: Bull. Soc. Chim. Beige 70, 136 (1961); b) Anthoine, G., J. Nasielski et E. Vander Donckt: Bull. Soc. Chim. Beige (sous presse).

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Associé du F.N.R.S.

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Aspirant du F.N.R.S.

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Nous exprimons notre gratitude à Monsieur le professeur R. H. Martin qui a suivi ces recherches avec le plus vif intérêt.Que le Ponds National de la Recherche Scientifique (F.N.R.S.) trouve ici l'expression de notre gratitude pour l'aide morale et financière dont nous avons bénéficié.Nos remerciements vont également au Fonds de la Recherche Scientifique Fondamentale Collective pour le subside octroyé au laboratoire.Nous tenons aussi à remercier très sincèrement Monsieur V. Bellevitch, Directeur du Comité d'Etude et d'exploitation des Calculateurs Electroniques, qui a mis au point le programme de résolution des équations séculaires et qui nous a fourni les vecteurs et valeurs propres utilisées dans ce travail.     

Spectres de vibration et coordonne´es normales de cinq espe`ces isotopiques d'allylamine

Infrared and Raman spectra have been recorded between 4000 and 100 cm⁻¹ for five isotopic species of allylamine. The spectra of a cis and two gauche conformers have been identified. From a qualitative assignment, two valence force fields have been calculated, one for the cis and the other for the gauche conformers.     

Spectres de vibration et calcul des champs de force des molécules P4O6, As4O6 et Sb4O6

The valence force fields of P₄O₆, As₄O₆ and Sb₄O₆ molecules have been computed using infrared and Raman vibrational frequencies; a unique potential function has been used. Complete sets of valence force constants are reported and the values of some force constants are discussed.     

Synthèse et propriétés de composés de neptunium(V) formés avec le ligand polyazoté Tptz

Synthesis and properties of Np(V) compounds formed with nitrogen planar ligand Tptz. Under special conditions, Np(V) compounds are formed with N-donor aromatic ligands. In this work, synthesis as well as optical properties and thermal stability of solids [NpO₂Cl(Tptz)H₂O]·H₂O (I) and NpO₂Br(Tptz)·n H₂O (II) are investigated. To cite this article: N.A. Budantseva et al., C. R. Chimie 8 (2005).     

Spectres de vibration et coordonne´es normales de quatre espe`ces isotopiques d'alcool allylique

Infrared and Raman spectra have been recorded between 4000 and 200 cm⁻¹ for four isotopic species of allyl alcohol in the gaseous, liquid and glassy states, and in argon or nitrogen matrices at 20 K. After identification of the spectra of two conformers, cis and gauche, and from a qualitative assignment a normal coordinate analysis and a valence force field have been computed for each isomer. Changes in force constants from one conformer to the other are discussed in term of electronic charge distribution in the molecule.     

Application de la chélatométrie au dosage du fluor dans les composés organiques

Fluorine bound in organic matter can be determined volumetrically, after decomposition with sodium peroxide, by precipitation by means of a calcium chloride solution, the excess of which is measured chelatometncally     

Méthode de dosage du nickel métallique en présence de composés oxydés de nickel dans des matières complexes (minerals)

During investigations on the behaviour of metallic nickel in HgCl₂-, KCN- and HCl-containing media, it was noticed in certain cases that nickel metal dissolution was achieved, while a mixture of nickel oxides remained absolutely unaltered.The working conditions were determined, and on the basis of the results obtained two methods have been developed for the determination of metallic nickel in the presence of nickel oxides in complex materials, including ores.These methods are described, in detail and the results of the experiments are given: they show that an accuracy of about 5 % can be obtained.     

Spectres de vibration et liaison hydrogène dans le furanne 2,5-dicarboxylate acide de potassium

The symmetry of the H-bond of crystals of potassium hydrogen (and deuterium) furan 2,5-dicarboxylate (Fur 2,5-HK and Fur 2,5-DK) was studied by i.r. and Raman spectroscopy. The isotopic ratio (ν_asOHO/ν_asODO = 1.40) and selection rules in terms of factor group C_2h indicate that the H-bond is truly symmetric; the proton is on C_i site and its potential function has a symmetrical single minimum. An assignment of fundamental vibrations is proposed.     

Bandes de vibration symétrique dépolarisées

Point group symmetry is an incomplete representation of a molecule containing chemically equivalent, but symmetrically non equivalent, bonds (Fe(CO)₅, Fe(CO)₄L,…). Raman spectra of these molecules display a depolarization of some symmetric vibration bands. It is shown that this property is a consequence of the chemical equivalence of the bonds and should be observed in all the similar cases.The present calculation, Bor's principle of equi-amplitude, and Edgell's theory of hidden symmetry, which lead to the same expectations, are compared.     

Interprétation des spectres Raman du butyne-2, du pentyne-2 et de quelques composés analogues deutériés ǎ l'état liquide; étude de la résonance de Fermi affectant la vibration ν(CC)

The Raman spectra of three 2-butynes: CH₃CCCH₃, CH₃CCCD₃ and CD₃CCCD₃, and four 2-pentynes: C₂H₅CCCH₃, C₂H₅CCCD₃, C₂D₅CCCH₃ and C₂D₅CCCD₃ in the liquid state have been measured. From a comparative analysis of the spectra, together with previous work on 1-butynes, a vibrational assignment is derived. The analysis of the 2000–2400 cm⁻¹ range allowed us to precise the Fermi resonance interaction between ν(CC) and 2ν_a(CC

CC). An assignment of the several bands shown by the Raman spectrum of 3-hexyne in this range has been proposed.     

Activité antiplasmodiale in vitro des composés isolés des écorces du tronc de Vitex thyrsiflora

Phytochemical study of Vitex thyrsiflora (Verbenaceae), a medicinal plant commonly used in traditional medicine to treat malaria, have allowed to isolate six compounds identified 20(R),24(E)-3-Oxo-9β-lanosta-7,24-dien-26-oic acid (1), α-amyrin (2), β-amyrin (3), friedelin (4), β-sitosterol palmitate (5) and a sterol glucoside (6). All these compounds were isolated for the first time in this plant. Their structures were determined on the basis of their physical and spectroscopic data (IR, MS, UV, NMR) and by comparison of these data with those reported in the literature. Compound 5 showed significant antiplasmodial activity with IC₅₀ of 3,09 and 8,98 μg/mL against multi-resistant strains Dd2 and K1 of P. falciparum. All these constituents were isolated from this plant for the first time. The tested compounds were non-cytotoxic on the LLC-MK2 monkey kidney epithelial cells. The results obtained can justify the use of Vitex thyrsiflora stem bark in traditional medicine for the treatment of malaria.     

Decontamination chimique. II. Oxydation de composés soufrés en milieu micellaire: rôle de la lipophilie des substrats

Chemical decontamination of toxic compounds (warfare agents and pesticides) is of increasing importance. Oxidation of sulphur-containing model toxic agents in micellar media (in water or binary systems) was investigated through the relationship between the reactivity/ selectivity and the lipophilicity (log P)) of the model.Two substrates with lipophilicities close to that of mustard seem to be the best suited for miming the degradation of the toxin. The micellar medium composed of cetylpyridinium chloride and of the binary system water/ formamide (1:1; vol/vol) gave the best results: quantitative yield with over 90 % of the product in the form of sulphoxide.     

Synthèse de composés macrocycliques comportant deux fragments coordinants séparés et différents,de type bipyrldyl-2,2' et diphényl-2,9 phénanthroline-1,10.

Macrocyclic compounds containing a 2,9-diphenyl -1,10-phenanthroline subunit and a peripheral 2,2'-bipyridine chelate have been synthesized. In compound 4, the links between both coordinating fragments are flexible enough to allow complete folding of the molecule during complexation whereas in 5, the complexing moieties are rigidly held apart and cannot bind to the same metallic center.