C-I stretching vibrations in iodobenzenes

Comparison of the calculated and experimental IR and Raman spectra of a series of iodobenzenes showed that the C-I stretching vibrations for these compounds correspond to a very highly polarized Raman band at 150–270 cm^–1 (=0.1). The position of this band depends on the mass of the para substituent and relative position of the fluorine and iodine atoms in the molecule. The UV absorption spectral data indicate an interaction of the iodine atom and para substituents through the -system. Opposite substituent effects on the change in intensity of the B-band in the UV spectra of iodobenzenes and tetrafluoroiodobenzenes were noted.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2637–2639, November, 1991.     

Derivatives of condensed systems based on pyrimidine,pyrazine, and pyridine

Pyrimido[4,5-b]-1,4-thiazin-6-one and pyrimido[4,5-b]-1,5-thiazepin-6-one derivatives were obtained by reaction of 5-amino-6-chloropyrimidines with thioglycolic acid and 5-amino-6-mercaptopyrimidines with -bromopropionyl chloride. The IR spectra of the compounds are presented.See [1] for communication XXXV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1332–1335, October, 1977.     

Flavonoids ofArtemisia transiliensis

Conclusions FromArtemisia transiliensis we have isolated a new glycoside and have called it transilin. On the basis of spectral and chemical investigations the structure of 3-O-methylquercetin 7--D-glucopyranoside has been proposed for it.Khimiya Prirodnykh Soedinenii, Vol. 5, No. 4, pp. 236–239, 1969     

Zwitterionic ion chromatography with carboxybetaine surfactant-coated particle packed and monolithic type columns

Both particle packed (25 cm x 0.46 cm I.D. SUPELCOSIL 5 microm C18) and monolithic type (10 cm x 0.46 cm I.D. Merck Chromolith Performance C18) reversed-phase substrates were dynamically coated with a carboxybetaine type zwitterionic surfactant ((dodecyldimethyl-amino) acetic acid) and investigated as stationary phases for use in zwitterionic ion chromatography (ZIC). Investigations into eluent concentration and pH were carried out using KCl eluents containing 0.2 mM of the carboxybetaine surfactant to stabilise the column coatings. It was found that eluent concentration decreased anion retention whilst simultaneously increasing peak efficiencies, which may be due to the dissociation of intra- and inter-molecular salts of the carboxybetaine surfactant under higher ionic strength conditions. The Effect of eluent pH was an increase in anion retention with decreased eluent pH due to the increased protonation of the weak acid terminal group of the carboxybetaine, causing both a relative increase in the positive charge of the stationary phase and less repulsion of the anions by the dissociated weak acid group. The carboxybetaine-coated monolithic phase was applied to rapid anion separations using elevated flow rates and flow rate gradients.     

Tetraphenylphosphonium Diiodobromide: Crystal and Molecular Structure

Complex formation in systems containing 3-carboxypropyltriphenylphosphonium or tetraphenylphosphonium bromide, molecular iodine, and chloroform solution was compared. The maximum number of iodine molecules coordinated by bromides in the solution was established by spectrophotometric method using a function of average iodine number and the stability constants of the complexes were determined. The diiodobromide [(C₆H₅)₄P]BrI₂ was studied by X-ray diffraction analysis. The ab initio calculations were performed for [Y(R)₄]I₃ (Y = N, P, As; R = CH₃, C₆H₅). The obtained experimental data and the correlations with the results of quantum-chemical calculations revealed that the tetraphenylphosphonium cation binds diiodobromide anions through the terminal halogen atoms with equal probability.     

Photometrische Bestimmung von kleinen Mengen Chlorid in Selen, Tellur, Gallium und Wismut

Zusammenfassung Die Probe wird mit Salpetersäure in Gegenwart von Silbernitrat gelöst. Das entstandene Silberchlorid trennt man durch Zentrifugieren ab und zersetzt es anschließend mit Chromschwefelsäure in einer Bestimmungsapparatur. Dabei entstehende flüchtige Chlorverbindungen werden in einer schwefelsauren Kaliumpermanganatlösung zu Chlor oxydiert, das mit o-Tolidin ein gelbes Oxydationsprodukt bildet. Die Extinktion dieser Gelbfärbung wird photometrisch gemessen und die entsprechenden Chloridmengen an Eichgeraden ermittelt. 1–100 g Chlorid können bestimmt werden. Die Standardabweichung beträgt für den Bereich 1–10 ppm maximal ±0,6 ppm Cl und bei der Bestimmung von etwa 200 ppm maximal ± 2,8 ppm Cl.

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Photometric determination of small amounts of chloride in selenium, tellurium, gallium and bismuth

The sample is dissolved in nitric acid in presence of silver nitrate. The silver chloride is separated by centrifuge and decomposed in a glass equipment by chromosulphuric acid. Resulting volatile compounds of chlorine are oxidized by potassium permanganate in sulphuric acid solution to chlorine, which forms with o-tolidine a yellow oxidation product. The absorbance of this coloration is measured by photometry and corresponding amounts of chloride are found out by calibration curves. 1 to 100 g of chloride can be determined in the range of 1 to 10 ppm Cl with a standard deviation of ±0.6 ppm Cl and at approximately 200 ppm Cl with ± 2.8 ppm Cl.

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Wir danken Herrn Dr. G. Iwantscheff, Forschungslaboratorien der Siemens AG, für wertvolle Anregungen und Herrn Dr. v. Sturm, Forschungslaboratorien der Siemens AG, für die Überlassung von polarographisch ermittelten Chlorgehalten in Selenproben.     

Dual phosphorescence from 5-methylbicyclo[4.3.01,5]non-1-en3-one

Phosphorescence has been simultaneously observed from both a ³π, π* and a ³n,π* level of 5-methylbicyclo-[4.3.0^1,5non-1-en-3-one. The emission from the higher energy ³n,π* state, which is in thermal equilibrium with the ³π,π* state, is quenched by lowering the temperature and also quenched by increasing the solvent polarity so as to raise the energy of the ³n,π* state relative to the ³π,π* state.     

Thermodynamische Eigenschaften des Systems Gold-Platin-Palladium

Ohne Zusammenfassung

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Thermodynamic properties of the system Au-Pk-Pd

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Mit 2 Abbildungen

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Herrn Prof. Dr.H. Nowotny gewidmet.     

Functionalization of the macropolyhedral borate anion cluster [B22H22]: isolation and characterization of the OH and OEt derivatives

Preparation and characterization of the first derivatives of the fused macropolyhedral anion [B₂₂H₂₂]²⁻ are reported. The species [B₂₂H₂₁OH]²⁻ (1) and [B₂₂H₂₁OEt]²⁻ (2) are obtained from workup of the products of the reaction between HgBr₂ and [NBzlEt₃]₂[B₂₂H₂₂]; a cluster involving the conjoining of a closo-B₁₂ icosahedron with a nido-B₁₀ cluster. Washing the products with ethanol followed by thin-layer chromatography allows the isolation of 1 and 2, reproducibly, in yields of 27 and 20%, respectively. The species were characterized by NMR spectroscopy, elemental analysis and X-ray diffraction studies. The crystal structure determinations of the two species identify novel features. Apparently the influence of the O atoms in the ions [B₂₂H₂₁OH]²⁻ and [B₂₂H₂₁OEt]²⁻ results in the lengthening of what was a gunwale B---B connection adjacent to the junction of the two cages such that the distances are 2.180 and 2.230 Å, respectively. These latter are longer than the corresponding distance in the parent species [B₂₂H₂₂]²⁻, which is 2.09 Å; quite long for a normal B---B distance. Thus it is assumed that these B atoms, in 1 and 2, one of which bears the substituent, are not bonded to each other.     

Solvent water tapes in two hydrates of μ‐oxo‐bis­[bis­(2,2′‐bipyridine‐κ2N,N′)(sulfato‐κO)iron(III)]

The title compound, [Fe₂O(SO₄)₂(C₁₀H₈N₂)₄], crystallizes as two different hydrates, viz. 11H₂O, (I), and 15H₂O, (II). The complex is binuclear, in which the two Fe^III atoms are coordinated in an octa­hedral geometry to four N atoms from the two bipyridine ligands, to one O atom from the sulfate ion and to an oxide ion on a twofold axis, which acts as a bridge between the symmetry‐related units. The Fe⋯Fe separation is 3.556 (4) Å and the Fe—O—Fe angle is 161.6 (2)° in (I); the corresponding values are 3.544 (1) Å and 165.8 (2)° in (II). In (II), one of the O atoms of the sulfate ion is disordered over two positions. In both compounds, the solvent water mol­ecules form slightly different one‐dimensional hydrogen‐bonded networks which pass along the c axis of the unit cell. In (I), three solvent water mol­ecules and, in (II), one solvent water mol­ecule, are situated on the twofold axis. In both (I) and (II), the central O atom of the metal complex lies on a twofold axis.