Flammenphotometrische Bestimmung geringer Kaliummengen in Natrium und seinen Verbindungen nach Anreicherung mittels Tetraphenylborammonium

Zusammenfassung Das hier beschriebene Verfahren gestattet, in metallischem Natrium oder in Natriumsalzen bei einer Einwaage von 1 g Kaliumgehalte bis herunter zu 10^–4% mit einem mittleren Fehler von ± 5% zu bestimmen. Der flammenphotometrischen Messung geht eine Anreicherung des Kaliums durch Konzentrationsfällung mit Ttraphenylborammonium voraus.Herrn Dr. Spang, Forschungslaboratorium der Siemens-Schuckertwerke, danken wir für seine Mithilfe bei der Durchführung der radiochemischen Untersuchungen, Herrn Dr. Iwantscheff für das der Arbeit entgegengebrachte fördernde Interesse.     

Reaction of silylphosphites with secondary amines

The reaction of dialkylsilylphosphites with linear and cyclic secondary amines leads to the formation of acid alkoxydialkylamidophosphites and dialkyl phosphites. Aminolysis of pyrocatecholsilylphosphite was accomplished with retention of the phosphorus atom and formation of the corresponding amidophosphites.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 235–237, January, 1991.     

Molecular and crystal structure of the germacranolide argolide from Artemisia glabella

The new germacranolide argolide has been isolated from the epigeal part ofArtemisia glabella, and its structure has been shown by its conversion into oxopelenolide B. From the results of an x-ray investigation it is suggested that argolide has the spatial structure of 3-oxo-4α,7α,6β(H)-germacra-1(10),11(13)-dien-6,12-olide. Institute of Organic Synthesis and Coal Chemistry, Kazakh Academy of Sciences, Karaganda. A. N. Nesmeyanov Institute of Organometallic Chemistry, Russian Academy of Sciences, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 653–657, September–October, 1991.     

Structure of subchrysin

A new sesquiterpene lactone having the structure 3-acetoxy-1-hydroxy-6, 7(H)-germacra-4,10(14), 11(13)-trien-6, 12-olide has been isolated fromArtemisia subchrysolepis Filat. and has been called subchrysin. Its stereochemistry has been established by x-ray structural analysis.Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 176–180, March–April, 1998.     

Determination of gallium in tumour-affected tissues by means of spectroscopic techniques

A comparative investigation was carried out on the suitability of atomic absorption spectrometry and of emission spectrography with arc and hollow-cathode excitation sources for determination of gallium (μg g^-1) in biological samples. The three methods give reliable results. Hollow-cathode emission spectrography was found to be influenced to a lesser extent by matrix effects and to be more precise than the other two techniques.     

Substituted dienic 1,3-dioxolan-2-ones and bis(1,3-dioxolan-2-ones)

Alkylthio-substituted dienic 1,3-dioxolan-2-ones and bis(4,4-diorganyl-5-methyli-dene-1,3-dioxolan-2-ones) were obtained in high yields by the reaction of 2-methyl-6-alkylthio-5-hexen-3-yn-2-ols and tertiary diacetylenic glycols with carbon dioxide under pressure in the presence of catalytic amounts of triethylamine and monovalent copper salts.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1617–1619, December, 1979.Original article submitted January 24, 1979.     

(PPh3Me)2[{MoCl4(NO)}2 (μ-S2N2)]; Synthese,IR-Spektrum und Kristallstruktur

(PPh₃Me)₂[{MoCl₄(NO)}₂(μ-S₂ N₂)]; Synthesis, I.R. Spectrum, and Crystal Structure The title compound is prepared by the reaction of (PPh₃Me)₂[MoCl₃(NO)₂]₂ with trithiazyl chloride in CH₂Cl₂ solution. It forms yellow, only slightly moisture sensitive crystals, which are characterized by their IR spectrum as well as by an X-ray structure determination. (PPh₃Me)₂[{MoCl₄(NO)}₂ (μ-S₂N₂)] crystallizes triclinic in the space group P1 with one formula unit in the unit cell (5952 independent, observed reflexions, R = 0.045). The lattice dimensions are at 20°C: a = 1021, b = 1143, c = 1243, pm; α = 64,15°, β = 68.24°, γ = 80.85°. The compound consists of PPh₃Me⊕ cations and anions [{MoCl₄(NO)}₂(μ-S₂N₂)]²?, in which the molybdenum atoms are bridged by the N-atoms of the planar S₂N₂ ring. In the trans-positions of these N-atoms the linear nitrosyl groups are coordinated via Mo ? N ? O .     

Comparison of theory and experiment for excited singlet states of the H2 molecule

This paper presents a survey of published and unpublished ab initio calculations of the vibrational structures of the ten lowest electronic singlet states of the hydrogen molecule up to the H(n = 1) + H(n = 2) dissociation limit. The data are based on adiabatic potential functions (clamped-nuclei electronic energies and nuclear-mass-dependent diagonal corrections). Nonadiabatic coupling has been treated ab initio within the five states. of ¹Λ symmetry (X,EF, GK, HH?) and ¹Σ I.¹Π_g. The accuracies of the theoretical energies are determined by comparisons with experimental data for H₂, HD, and D₂. The level shifts and predissociation probabilities of the excited ¹Σ states, generated by nonadiabatic coupling with the discrete and continuous vibrational structure of the ground state, and radiative properties have also been calculated.