The polarized ion model and the bending force constants of the group IIB halides

The applicability of the polarized ion model to the bending force constants of the group II metal dihalides is examined. Calculations are carried out for zinc, cadmium and mercury halides and show that the force constant values obtained are insensitive to the anion polarizability values used, but are quite sensitive to the metal ion polarizability values. It is shown that available polarizability values are not applicable to the group II dihalides. Therefore, force constant calculations with the metal ion polarizability as a variable parameter are carried out. Results agreeing with experimental values of the bending force constants are obtained for reasonable polarizability values, except for the case of the mercury halides. This discrepancy is discussed.

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Zusammenfassung Die Anwendbarkeit des polarisierten Ionenmodels zur Berechnung der Kraftkonstanten der Beugungsschwingung bei Metalldihalogeniden der Gruppe II wird untersucht. Berechnungen für Zink-, Cadmium- und Quecksilberhalogeniden werden durchgeführt und zeigen, daß die Werte für die Kraftkonstanten nur schwach von der Polarisierbarkeit der Anionen, dagegen ziemlich stark von der Polarisierbarkeit der Metallionen abhängen. Weiter wird gezeigt, daß die in Betracht kommenden Polarisierbarkeiten für die Dihalogenide der Gruppe II zu keinen sinnvollen Ergebnissen führen. Deshalb wurden die Berechnungen mit der Metallionen-Polarisierbarkeit als variablem Parameter ausgeführt. Resultate, die mit den experimentellen Werten übereinstimmen, wurden für vernünftige Polarisierbarkeiten erhalten. Die Quecksilberhalogenide bilden eine Ausnahme, die diskutiert wird.

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Résumé Examen de l'applicabilité du modèle de l'ion polarisé pour le calcul des constantes de force de déformation des dihalogénures des métaux du groupe II. Des calculs sont effectués pour les halogènures de zinc, cadmium et mercure, montrant que les valeurs obtenues pour les constantes de force sont insensibles aux valeurs des polarisabilités de l'anion, mais sont assez sensibles à celles de l'ion métallique. On montre que les polarisabilités disponibles ne sont pas applicables aux dihalogènures du groupe II. De ce fait les calculs de constante de force sont menés avec la polarisabilité variable pour l'ion métallique. Des résultats en accord avec les valeurs expérimentales des constantes de force de déformation sont obtenues pour des valeurs raisonnables de la polarisabilité, sauf dans le cas des halogènures de mercure. Cette discordance est discutée.

     

Solid-phase reagent for molecular spectroscopic determination of heavy metal speciation in natural water

A solid-phase reagent based on 1-(4-adamantyl-2-thiasolylazo)-2-naphthol adsorbed onto silica gel was prepared for Co(II) recovery and preconcentration prior to its sorption-spectroscopic detection. The immobilized reagent was applied to the determination of free cobalt ions in natural water. The solid-phase reagent and chemiluminescent method coupled with membrane filtration, gel-permeation and ion-exchange chromatography were applied to the study of the speciation of iron and cobalt in water from the Dnieper reservoirs and lakes of Kyiv City; their predominant forms were complexes of Fe(III) and Co(II) with dissolved organic matter and fulvic acids play a main role in their complexation.     

Properties and structures of porphyrexides

The molecular and crystal structures of porphyrexides, viz., 4-amino-2-imino-(1) and (Z)-2-amino-4-bromoimino-5,5-dimethyl-4,5-dihydro-1H-imidazole 1-oxyls (7), and their diamagnetic precursors were determined. Compound 1 is kinetically unstable because it is oxidized with atmospheric oxygen to form (E)-1,2-bis[1-amino-1-(cyanoimino)-2-methyl-propan-2-yl]diazene 1,2-dioxide. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 441–447, March, 2006.     

Heterometallic nickel(II) samarium(III) diethylenetriaminepentaacetate, a starting material for the preparation of samarium nickelate films

A reaction of samarium oxide, nickel oxocarbonate, and diethylenetriaminepentaacetic acid (H₅DTPA) taken in stoichiometric proportions in water gave SmNiDTPA · 10H₂O as a glassy solid. The formation of this heterometallic complex was confirmed by data from elemental analysis, IR spectroscopy, thermal analysis, and X-ray fluorescence analysis. An aqueous solution of the complex was used to deposit SmNiO₃ films onto a single-crystal SrTiO₃(001) substrate. The SmNiO₃ phase in films obtained upon 3-h annealing at 500°C was identified by powder X-ray diffraction. Films deposited from a solution of an equimolar mixture of monometallic samarium and nickel diethylenetriaminepentaacetates contained no samarium nickelate.     

Kinetic parameters obtained from TG and DTG curves of acrylamide-maleic anhydride copolymers

The thermal behaviour of acrylamide-maleic anhydride copolymers was studied by thermogravimetric (TG and DTG) analysis. The obtained data permitted the calculation of activation energies and reaction orders of the decomposition steps by the Coats-Redfern and Freeman-Carroll methods.Thermal analysis shows four distinct peaks in the case of polyacrylamide and AAMA (71) copolymer and only three for AAMA (11) copolymer.In AA:MA (11) copolymers intermolecular imidization occurs only and thermal degradation is influenced more by the anhydride groups which are equal in number with the amide ones.

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Zusammenfassung Das thermische Verhalten von Acrylamid-Maleinsäureanhydrid-Kopolymeren wurde durch thermogravimetrische Analyse (TG und DTG) untersucht. Aus den erhaltenen Daten wurden die Aktivierungsenergien und Reaktionsordnungen der Zersetzungsschritte nach den Methoden von Coats-Redfern und Freeman-Carroll berechnet. Durch thermische Analyse können im Falle von Polyacrylamid und AAMA (71 (-Kopolymeren 4 Peaks und bei AA:MA (11) -Kopolymeren nur 3 Peaks unterschieden werden. Bei AAMA (1 1)-Kopolymeren verläuft nur eine intermolekulare Imidisierung und der thermische Abbau wird mehr durch die in gleicher Zahl wie die Amidgruppen vorliegenden Anhydridgruppen beeinflußt.

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T () — (). , - -, . : ( 71) , : 11 — . : 11 , , .

     

Analytical Application of Silica Gel Modified with Didecylaminoethyl-beta-Tridecylammonium Iodide

Sorption of a high molecular weight quaternary ammonium salt, didecylaminoethyl-β-tridecylammonium iodide (DDATD) on different types of sorbents was investigated. The nature of reagent adsorption on silica gel was examined by spectroscopic and computer methods. The sorption of anionic metal complexes of cobalt, copper, zinc and manganese on silica gel modified with DDATD was studied. The possibility of recovery of cobalt and copper thiocyanate complexes and their further atomic absorption determination is shown. Modified sorbent was applied to cobalt chemiluminescence and determined in natural water and a nickel preparation (detection limit, 2 μg/l.).     

Flavonoids of the peel of the fruit ofCitrus unshiu

Institute of Biochemistry, Academy of Sciences of the Georgian Republic, Tbilisi, and Samara Medical Institute, Russia. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 821–822, November–December, 1994.