Synthesis and Crystal Structure of the Hydrogen Polyphosphide Bis(Tetraphenylphosphonium) hydrogenheptaphosphide‐ammonia(1/3) (PPh4)2HP7 · 3NH3

(PPh₄)₂HP₇ · 3NH₃ was prepared by the reaction of K₃P₇ with a proton‐charged ion exchange resin in the presence of (PPh₄)Br in liquid ammonia, and characterized by low temperature X‐ray structure analysis. The thermally very unstable compound contains the hydrogenheptaphosphide anion HPequation/tex2gif-stack-1.gif, the nortricyclane‐like cage of which is slightly distorted by the attachment of the hydrogen atom.     

Evaluation of a purge-and-trap injection system for capillary gas chromatography-microwave induced plasma-atomic emission spectrometry for the determination of volatile selenium compounds in water

A method is presented for the selective determination of the volatile selenium species dimethylselenide and dimethyldiselenide, using a commercially available purge-and-trap injection system coupled to capillary gas chromatography-microwave induced plasma-atomic emission spectrometry. The efficiency of the purging step was evaluated and the parameters affecting the purge and trap processes were optimized. The method was applied to the determination of volatile selenium compounds in lake water. Relative detection limits of 2ng/l for dimethylselenide and dimethyldiselenide, corresponding to an absolute detection limit of 10 pg, were achieved.     

Highly efficient recycling of a "sandwich" type polyoxometalate oxidation catalyst using solvent resistant nanofiltration

A "sandwich" type polyoxometalate catalyst ([MeN(n-C8H17)3]12[WZn3(ZnW9O34)2]) was very efficiently recycled by nanofiltration with almost quantitative retention, using an alpha-alumina supported mesoporous gamma-alumina membrane.     

Vesicle Phases with Semipolar Additives

We examined the influence of semipolar additives on the phase behavior of mixed zwitterionic surfactant/consurfactant systems. It is shown that in these systems with increasing concentration esters like hexylacetate (HA) and ketones like hexylmethylketone (HMK) can behave both like consurfactants and like hydrocarbons. In solutions of 200 mM tetradecyldimethylamineoxide (TDMAO)/cosurfactant the additives cause first a phase transformation from the micellar L(1) phase to a lamellar L(alpha) phase. Upon further increasing concentration, the L(alpha) phase is transformed into a microemulsion. The L(alpha) phase consists of densely packed multilamellar vesicles. The vesicles are shown by electron microscopy. The multilamellar character of the vesicles is also reflected in the conductivity of the phase. It is up to 10 times lower than the conductivity of the L(1) phase. In some systems the vesicles are transformed on rest into a multidomain stacked L(alpha) phase. It is furthermore demonstrated that the two-phase L(1)/L(alpha) region in these systems is very narrow. In situations where enough HA is added to be close to the boundary of the L(1) phase, it is shown that very small amounts of cosurfactant can transform the L(1) phase into the L(alpha) phase. In extreme situations 1 mM cosurfactant is sufficient for transforming the L(1) phase with 200 mM TDMAO into the L(alpha) phase. In the investigated systems the L(alpha) phase is a highly viscoelastic fluid in which the storage modulus is 1 order of magnitude larger than the loss modulus. Besides the conventional way to prepare samples by adding all ingredients and stirring the solution intensively, all investigated systems were additionally prepared without applying any shear forces. In a surfactant/cosurfactant solution the additive was brought into the sample by diffusion. The phase behavior of both types of samples showed fundamental differences in some cases, which give insight into the influence of shear forces on these systems. Copyright 2001 Academic Press.     

As12Se44—: ein neuartiges Selenoarsenatanion mit einem Polyarsenkäfig in der Verbindung [Co(NH3)6]2As12Se4 · 12 NH3

As₁₂Se₄^4—: a New Selenoarsenate Anion with a Polyarsenic Cage in the Compound [Co(NH₃)₆]₂As₁₂Se₄ · 12 NH₃ Orange coloured crystals of [Co(NH₃)₆]₂As₁₂Se₄ · 12 NH₃ were prepared by the reduction of As₄Se₄ with a solution of sodium in liquid ammonia and subsequent precipitation with CoBr₂. The X‐ray structure determination shows them to contain the selenoarsenate anion As₁₂Se₄^4—, which consists of a central As₁₂‐cage with four exo‐bonded, formally negatively charged Se atoms. The structure of the As₁₂‐cage is equivalent to the main polyphosphorus building unit of a known organopolyphosphane and of tubular P₁₂ in the compound (CuI)₃P₁₂.     

Synthese von 8-Alkylamino-8-aryl-1,2,3,4,5,6-hexathiocan-7-thionen

Zusammenfassung Durch gemeinsame Einwirkung von primären aliphat. Aminen und Schwefel auf Methylarylketone in Methanol bei Raumtemp. erhält man in meist guten Ausbeuten 8-Alkylamino-8-aryl-1,2,3,4,5,6-hexathiocan-7-thione (1a-h). Die Umsetzung von 1,4-Diacetylbenzol mit n-Propyl-bzw. n-Butylamin und Schwefel liefert Phenylen-1,4-di-hexathiocanderivate (3 a, b).Bei der Reaktion von Acetophenon mit 3-N,N-Diäthylaminopropylamin und Schwefel entstehen neben dem 8-(3-N,N-Diäthylaminopropylamino)-8-phenyl-1,2,3,4,5,6-hexathiocan-7-thion (1e) 51% einer Verbindung der Summenformel C₁₅H₂₂N₂S₂ (2), der die Struktur der (3-N,N-Diäthylaminopropylimino)-phenyldithioglyoxylsäure zugeordnet wird.1 e läßt sich durch Behandlung mit wäßr. Natriumsulfit-Lösung zu2 abbauen,2 durch Reaktion mit Schwefel wieder in1 e überführen.

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Synthesis of 8-alkylamino-8-aryl-1,2,3,4,5,6-hexathiocan-7-thiones (Joint action of elemental sulfur and gaseous ammonia upon ketones, LXXVIII: Action of sulfur and amines on acetophenone, IX)

8-Alkylamino-8-aryl-1,2,3,4,5,6-hexathiocan-7-thiones (1a toh) are obtained mostly in good yields by the concomitant action of primary aliphatic amines and sulfur upon methyl aryl ketones in methanol at room temperature. Reaction of 1,4-diacetyl benzene and sulfur with n-propylamine or n-butylamine respectively leads to phenylene-1,4-dihexathiocane derivatives (3 a, b).Besides 8-(3-N,N-diethylaminopropylamino)-8-phenyl-1,2,3,4,5,6-hexathiocan-7-thione (1 e), which is obtained by reaction of acetophenone with 3-N,N-diethylaminopropylamine and sulfur, a product with the formula C₁₅H₂₂N₂S₂ (2) is isolated in 51% yield, to which the structure (3-N,N-diethylaminopropylimino)phenyl dithioglyoxylic acid is assigned. By treatment of1 e with aqueous sodium sulfite solution2 is obtained, which can be transformed back into1 e by reaction with sulfur.

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77. Mitt.:F. Asinger, A. Saus, H. Offermanns undP. Scherberich, Ann. Chem.753, 151 (1971).

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8. Mitt.:F. Asinger, A. Saus, H. Offermanns undF. Abo Dagga, Ann. Chem.723, 119 (1969).

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Teil der DiplomarbeitJ. Hartig, Techn. Hochschule Aachen, 1969.     

Surface second-harmonic generation: A novel technique for ps-pulse duration measurements

Second-harmonic generation from dye adsorbates has been successfully used to measure the duration of ps pulses. In the red and in the blue-green spectral range pulse durations of 2.4 and 6.1 ps—in agreement with streak camera measurements — have been obtained from collinear, slow autocorrelation traces.