Über einige Eigenschaften von Zinkphosphiten mit Berücksichtigung ihrer Wasserstoffbrückenbindung

Zinc phosphites ZnPHO₃·2.5 H₂O, Zn₂H₂P₃H₃O₉·H₂O, Zn₃H₄P₅H₅O₁₅·1.5 H₂O, ZnH₂H₂P₂H₂O₆ have been studied at higher temperatures and by X-rays and molecular spectroscopy. Hydrates ZnPHO₃·2.5 H₂O and Zn₂H₂P₃H₃O₉·H₂O, when heated, yield an anhydrous salt. Thermal decomposition of dihydrogen triorthophosphite and tetrahydrogen pentaorthophosphite leads, before oxidation of the anion, to a mixture of zinc phosphite ZnPHO₃ and dihydrogen diorthophosphite ZnH₂P₂H₂O₆ and then after loss of water of constitution dihydrogen diorthophosphite converts to zinc diphosphite ZnP₂H₂O₅. The results of the thermal decomposition study were confirmed by X-ray investigation. Anhydrous zinc dihydrogen triorthophosphite Zn₂H₂P₃H₃O₉ and zinc diphosphite ZnP₂H₂O₅ were hitherto unknown. Infrared spectra confirmed the existence of hydrogen bonding in all the phosphites studied and in the case of zinc phosphite ZnPHO₃·2.5 H₂O exhibited a symmetry decrease of the anion PHO₃ ^2– from the point group C_3v to C_s. In the crystal lattice of ZnPHO₃·2.5 H₂O hydrogen bonding by water molecules participates, with polyorthophosphites hydrogen bonding shares in the production of anions and in the case of their hydrates there is in addition hydrogen bonding by water molecules.

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The Fermi doublet V2−V3 + V4 of CH3CN as a probe of molecular interactions

The Fermi doublet V₂?V₃ + V₄ of CH₃CN in basic, inert and acidic solvents has been studied by IR and Raman spectroscopy. The values of W, the Fermi coupling coefficient, obtained from IR spectra varies with the nature of the solvent while W evaluated from Raman data remains constant at 12.5 ± 0.5 cm^?1. The similar effects of Bronsted and Lewis acids on the band frequencies and intensities is evidence that the CN group complexes with acids via the N atom “n” electron pair and not the π bond.     

Rapid determination of ethylene glycol at toxic levels in serum and urine

The rapid gas chromatographic detection and determination of ethylene glycol in biological fluids is described. Phenylboronic acid in acetone was used for the esterification of glycol. The phenylboronates of ethylene glycol and 1,2-propylene glycol are not separated on a packed column of medium polarity (OV-17), but they can be separated on a non-polar column (OV-101). In both instances, 1,3-propylene glycol can be used as an internal standard. The method requires only 100 microliters of serum or urine and is suitable for trace analysis in an emergency toxicological laboratory. The utility of the method is demonstrated on two cases of human intoxication with ethylene glycol.     

Sequential atomic absorption spectrometric determination of nitrate and nitrite in meats by liquid-liquid extraction in a flow-injection system

Sequential determinations of nitrate and nitrite based on continuous liquid-liquid extraction, and suitable for their routine determinations in meats, are reported. Nitrate reacts with bis(2,9-dimethyl-1,10-phenanthrolinato)copper(I) to form an ion-pair which is extrated into 4-methyl-2-pentanone in a flow-injection manifold. In one aliquot of sample, nitrite is oxidized by cerium(IV), so that total nitrate is determined. In another, nitrite is converted to nitrogen with sulfamic acid, so that only the original nitrate is determined. By measuring the atomic absorption signal of copper in the organic phase, mixtures of these anions can be determined at μg ml^?1 levels for nitrate/nitrite ratios from 10:1 to 1:10, with a sampling frequency of ca. 20 h^–1.     

Reaction of mercury(II) and xylenol orange-I Effect of the buffering media

The influence of the buffering medium on the reaction of Hg(II) with Xylenol Orange has been studied. Amine-type compounds are complexed by Hg(II)/Xylenol Orange with a sharp hyperchromic effect on the reagent itself, at 590 nm, but complex formation of Hg(II)/Xylenol Orange in non-amine-type buffer, such as citric acid-phosphate, gives a hypochromic effect on Xylenol Orange at 580 nm. Hg(II) is determined at pH 7.5 in two ranges of concentration, 2-9 ppm in citrate buffer, measured at 580 nm ( = 2.50 x 10(4)), and 6-11 ppm in hexamine buffer, at 590 nm ( = 4.18 x 10(4)).     

The crystal structures of m-trifluoromethylphenylsilatranone and p-fluorophenylsilatranone

The crystal structures of two silatranone derivatives are reported. The close N → Si approach (2.106(3) Å in m-trifluoromethylphenyl-, and 2.129(3) Å in p-fluorophenyl-silatranone) indicates strong dative acceptor bonds. For various silatrane derivatives and inverse relation has been revealed between the mean group electronegativity of the substituent R attached to silicon and the N → Si dative bond distance. In both structures there are long (1.72 Å) SiO bonds in the SiOCO moiety. The m-trifluoromethylphenyl derivative contains a disordered CF₃ group.     

Anionic polymerization of vinyl chloride

Anionic polymerization of vinyl chloride has been studied. Of the organometallic compounds tested as initiators, only butyllithium was found to initiate polymerization. Polymerization in bulk at 0°C and with tert-butyllithium as initiator gave poly(vinyl chloride) in a yield of 38% with M _n = 55,000. Tacticity of the anionic PVC was similar to that of conventional PVC prepared at similar temperatures. Anionic PVC was found to be less branched and more heat-stable than the conventional polymer.     

Neue stellungsisomere reineckesalzähnliche Verbindungen mit Toluidinen

Zusammenfassung Es wurden eine Reihe von Substitutionsreaktionen mit entwässertem K₃[Cr(NCS)₆] und aromatischen Aminen, ohne Verwendung von Lösungsmitteln, durchgeführt. Es wurde beobachtet, da die sehr schwachen Basen mit p_K-Werten 14–16, wie die isomeren Mono- und Dinitro-aniline, die Anthranil- und Sulfanilsäuren, für diese Substitutionsreaktionen ungeeignet sind. Die Alkyl-anilinderivate, wie daso-, m- undp-Toluidin (p_K=10–11) bilden dagegen leicht reineckesalzähnliche Verbindungen: Amin· H[Cr(Toluidin)₂(NCS)₄]. Die Zusammensetzung der neuen Komplexanionen wurde bei einer Reihe von doppelten Umsetzungsreaktionen mit den Chlorhydraten einiger heterocyclischen Aminen festgestellt.Für die Klärung einiger Strukturfragen wurden spektrophotometrische Untersuchungen im UV und IR durchgeführt und die thermische Stabilität bzw. der Mechanismus des Pyrolysenvorganges auf thermogravimetrischem Wege verfolgt.

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Substitution reactions of anhydrous K₃[Cr(NCS)₆] with aromatic amines without applying of solvents were studied.It was observed, that the very weak bases (pK-values 14–16, e.g. isomeric mono- and dinitro-anilines, the anthranilic and sulfanilic acids) are unsuitable for substitution reactions. The alkylaniline derivates e.g.o-, m- andp-toluidine (pK=10–11) form easily reineckesalt analogous compounds: Amin· ·H[Cr(toluidine)₂(NCS)₄]·The formula of the 3 new complex anions: [Cr(toluidine)₂ (NCS)₄]- was established by preparative methods, with a series of double decomposition reactions, using chlorohydrates of some heterocyclic amines for this purpose. From spectroscopical investigations (UV and IR) some structural problems are resolved and discussed.The thermal stability and the mechanism of pyrolysis of these salts was studied by thermogravimetric analysis.

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Retention of85Sr and147Pm on insoluble hydroxides and phosphates prepared by the sol-gel procedure

Retention of strontium and promethium on hydroxides (hydrated oxides) and phosphates of iron and chromium prepared by the sol-gel method was studied. The sorption was determined under static conditions depending on the pH of the solution. The sorption isotherms and retention were investigated under dynamic conditions.     

Intramolecular "Aryl-metal chelate ring" pi,pi-interactions as structural evidence for metalloaromaticity in (aromatic alpha,alpha'-diimine)-copper(II) chelates: molecular and crystal structure of aqua(1,10-phenanthroline)(2-benzylmalonato)copper(II) three-hydrate

By reaction of Cu(2)CO(3)(OH)(2), 2-benzylmalonic acid (H(2)Bzmal), and 1,10-phenanthroline (phen), [Cu(Bzmal)(phen)(H(2)O)] x 3H(2)O (compound 1) has been obtained and characterized by thermal, spectral, magnetic, and X-ray diffraction methods. The molecular structure of 1 is remarkably similar to that of [Cu(Bzmal)(bipy)(H(2)O)] x 2H(2)O (compound 2, bipy = 2,2'-bipyridine). In both complexes, the aryl(Bzmal) ring produces an unexpected pi,pi-stacking interaction with the Cu(II)-(aromatic alpha,alpha'-diimine) chelate ring, at an average distance d(pi)(-)(pi) of 3.40 A, involving roughly parallel and smoothly slipped rings. This insight is discussed as new structural evidence for metalloaromaticity of Cu(II)-(aromatic alpha,alpha'-diimine) chelate rings. Interestingly, 1 recognizes itself by a weak intermolecular pi,pi-stacking interaction between aryl(Bzmal) ligands to give pairs of complex molecules. In contrast, there is an intermolecular pyridyl-pyridyl pi,pi-stacking interaction also forming pairs of complex molecules in 2.