Anhydrous photochemical uranyl(VI) reduction: unprecedented retention of equatorial coordination accompanying reversible axial oxo/alkoxide exchange

In a dramatic reversal of the normal trend of observed reactivity in uranyl(VI) coordination chemistry, an unprecedented retention of the normally labile equatorial coordination plane accompanies facile and reversible axial oxo/alkoxide exchange during both the photochemical reduction of cationic uranyl(VI) phosphine-oxide complexes with organic substrates and subsequent hydrolysis of the uranium(IV) alkoxide complexes to regenerate the uranyl(VI) starting complex.     

Na5(THF)10Ce(mnt)4]infinity: a honeycomb network polymer that yields homoleptic cerium(III) tetrakis(dithiolene) complexes in donor solvents

The first example of a lanthanide tetrakis(dithiolene) complex, [Na5(THF)10Ce(mnt)4] (1) (mnt = 1,2-maleonitrile-1,2-dithiolate), has been synthesized and characterized by X-ray crystallography and spectroscopic methods. In the solid state, 1 exists as a 2-D corrugated honeycomb network polymer in which the monomeric units comprising the trigonal nodes are knitted together by interlocking dative Na-N bonds extended from nitrile groups of bifunctional mnt ligands coordinated through the sulfur atoms to adjacent cerium centers. Individual honeycomb sheets are separated by 14.8 A. Compound 1 dissolves in donor solvents such as THF and acetonitrile to give soluble [Ce(mnt)4]5- units that exhibit spectroscopic features (i.e., NMR, luminescence, UV-vis) that are consistent with the 4f1 Ce(III) ion. In the first examination of the redox chemistry of a lanthanide dithiolene complex, cyclic voltammetry measurements conducted on 1 reveal a single irreversible oxidation wave that is likely attributable to ligand-centered oxidation.     

Organocatalytic synthesis of novel renewable non‐isocyanate polyhydroxyurethanes

Novel fully renewable AA‐BB type non‐isocyanate polyhydroxyurethanes were synthesized by the classical reaction between a diamine and a dicyclocarbonate. Sebacic acid was first reacted with an excess of glycerol carbonate, in presence of DCC and DMPA, leading to a renewable dicyclocarbonate monomer. Then, this monomer was reacted with several renewable diamines, in presence of 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD), as organocatalyst, to afford linear and branched polymers. The obtained materials exhibited T_g values varied from ?27 to ?8 °C, T_m values varying from 100 to 165 °C, and thermal stabilities above 200 °C. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 758–764     

Réaction spécifique pour le Palladium et son dosage

Résumé Parmi les dihydrazides des acides dicarboxyliques, le plus intéressant est celui de l'acide malonique qui fournit un réactif qualitatif spécifique du palladium. Le dosage gravimétrique ne s'applique pas, mais la colorimétrie permet d'évaluer de 2 à 10g/ml de palladium, à 285 nm.

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Specific reaction for palladium and its determination

Summary The most interesting of the dihydrazides of dicarboxylic acids is that of malonic acid, which yields a qualitative specific reagent for palladium. The gravimetric determination is not practicable but the colorimetric method permits the evaluation of from 2 to 10g/ml of palladium at 285 nm.

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Zusammenfassung Unter den Dicarbonsäure-Dihydraziden ist das interessanteste das der Malonsäure. Es ist ein für Palladium spezifisches Nachweisreagens. Zur gravimetrischen Bestimmung eignet es sich nicht, aber kolorimetrisch kann man bei 285 nm 2 bis 10g Pd/ml bestimmen.

     

Recherche microchimique de l'or sans réactif

Résumé Les auteurs décrivent une nouvelle méthode pour la recherche de l'or, en concentrant une solution d'or par vaporisation dans une tube capillaire, en chauffant le résidu et en l'enrobant dans le verre. Ainsi se forme une paillette d'or nettement visible, le verre fonctionnant comme loupe. On peut déceler 1 d'or dans 0,05 ccm. Quand la quantité d'or est encore plus petite, l'or en solution colloïdale forme un filet rose qui, sur un fond obscur, permet de déceler 0,05 d'or dans une goutte. On peut éviter de confondre l'or avec le cuivre, le seul métal, réagissant de même manière, en diluant la prise d'essai en solution. Les auteurs citent plusieurs exemples pour l'application de cette méthode.

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Summary A new method of detecting gold without adding reagents is described. Its chief features consist in evaporating a gold salt solution in a capillary tube, and heating the residue strongly enough to be embedded in molten glass. The gold spangle thus formed is rendered visible by the magnifying effect of the glass which wraps it. Limit of identification: 1 gold in 0,05 cc. If smaller amounts of gold are present, a colloidal solution of gold in glass, forming a pink thread, is obtained. As little as 0,05 Au in one drop can be detected by viewing this thread against a dark background. The test may be carried out in solutions of whatever acidity. A mistake caused by copper, the only metal reacting in a similar way, can be overcome by diluting the solution tested. Some applications of the method are described.

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Zusammenfassung Es wird ein neuer Goldnachweis ohne Reagenszusatz beschrieben, der darauf beruht, daß eine Goldlösung in einer Kapillare eingedampft, erhitzt und im Glas eingeschmolzen wird. Dadurch entsteht ein Goldflitterchen, das durch die Lupenwirkung des umhüllenden Glases deutlich sichtbar gemacht wird. Erfassungsgrenze: 1 Gold in 0,05 ccm. Bei kleineren Goldmengen entsteht ein rosa Faden von kolloid gelöstem Gold, der gegen einen dunklen Hintergrund noch den Nachweis von 0,05 Au im Tropfen ermöglicht. Der Nachweis ist in beliebig sauren Lösungen durchführbar. Eine Verwechslung mit Kupfer, dem einzigen ähnlich reagierenden Metall, läßt sich durch Verdünnung der Probelösung umgehen. Einige Anwendungen des Verfahrens werden beschrieben.

     

Thermodynamic characterization of a dichloromethane-xenon film adsorbed on (0001) graphite

Xenon adsorption between 95 and 115 K on graphite pre-plated with a dichloromethane monolayer results in a partial displacement of the pre-adsorbed layer and in the formation of a two-dimensional (dichloromethane-xenon) solution. When the dichloromethane pre-plating is in the sub-monolayer range, a xenon monolayer is condensed on the bare part of the surface before the composite layer organization. For dichloromethane coverages greater than a monolayer, kinetic problems arise for the formation of xenon bilayer patches, which implies in this case its separation from the two-dimensional solution.