Zur Reaktion von Derivaten des Thiosemicarbazids mit Bisimidchloriden der Oxalsäure

Summary Arylsubstituted oxalic bis-imidochlorides1 react with thiosemicarbazones of type5 as well as13 to give five-membered-ring heterocycles8,11, and16.¹³C-NMR spectroscopy, chemical methods and X-ray crystallography have been used to investigate the nature of the structures obtained. The¹³C-chemical shifts of13 and imidazolidines16 are correlated with Hammett _p constants and dual substituent parameters to evaluate the transmission of theX substitutent electronic effects via the side-chain iminyl carbon atom into the heterocyclic ring and its neighbouring phenyl groups.

     

Darstellung von Calcium- und Strontiumwolframat durch tribochemische Reaktion

Stoichiometric powder mixtures CaO/WO₃ and SrO/WO₃ react tribochemically on grinding in a vibrating mill to CaWO₄ and SrWO₄, respectively. IR spectra, X-raydiffraction, DTA and solubilities indicate at least 70–80% CaWO₄ are formed after periods of drinding of 50 hours, and 100% SrWO₄ after periods of 15 hours. Observations on the behaviour of the ground samples on subsequent annealing contribute to the general solid-state reaction MO + WO₃ → MWO₄.     

Synthesis, structure, and reactions of 1-tert-butyl-2-diphenylphosphino-imidazole

Metalation reactions were studied of a sterically demanding imidazole derivative, namely, 1-tert-butylimidazole (1), with different metalation reagents and subsequent reaction with diphenylchlorophosphane. The reaction product, 1-tert-butyl-2-diphenylphosphino-imidazole (2), was subjected to oxidation and complexation reactions to yield the corresponding products Ph(2)(Imi)P-E (E = O (3), S (4), Se (5), W(CO)(5) (8)) and in the case of borane-THF the N-BH(3) coordination product 10 was obtained. The analytical data of the new compounds are discussed, including X-ray diffraction studies of 3-5.     

Tethering versus Non‐Coordination of Hydroxy and Methoxy Side Chains in Arene Half Sandwich Dichloro Ruthenium Complexes

We are reporting on the hydroxyalkyl appended arene ruthenium half sandwich complexes [{η⁶‐C₆H₅(CH₂)_nOH}RuCl₂] (n = 2, 3) and the methyl ether of the hydroxypropyl derivative. Most significantly, a structural comparison between the hydroxypropyl complex 1a and its methyl ether 2a reveals, that the latter adopts the conventional dichloro bridged dimeric structure while 1a is a monomer. Coordinative saturation of the ruthenium centre is achieved by intramolecular coordination of the appended hydroxy function, thus rendering the functionalized arene an eight electron donor chelate ligand. The structure is further stabilized by intermolecular OH···Cl hydrogen bridges between a terminal chloride ligand of one and the coordinated hydroxy group of a neighbour molecule, resulting in a sheet structure. These intermolecular interactions appear to be even stronger in the hydroxyethyl analogue. Several phosphine adducts have been prepared from the hydroxy or alkoxy functionalized [(η⁶‐arene)RuCl₂]_n precursors, including water soluble P(CH₂OH)₃ adducts. Electrochemical properties of the phosphine adducts and of the dichloro bridged aryl ether complex 2a are also discussed.     

Rare Earth-Rich Indides RE 5Pt2In4 ( RE = Sc, Y, La–Nd, Sm, Gd–Tm, Lu)

The isotypic indides RE ₅Pt₂In₄ (RE = Sc, Y, La–Nd, Sm, Gd–Tm, Lu) were synthesized by arc-melting of the elements and subsequent annealing. They were investigated via X-ray powder diffraction. Small single crystals of Gd₅Pt₂In₄ were grown via slow cooling and the structure was refined from X-ray single crystal diffractometer data: Pbam, a = 1819.2(9), b = 803.2(3), c = 367.6(2) pm, wR ² = 0.089, 893 F ² values and 36 parameters. The structure is an intergrowth variant of distorted trigonal and square prismatic slabs of compositions GdPt and GdIn. Together the platinum and indium atoms build up one-dimensional [Pt₂In₄] networks (292–333 pm Pt–In and 328–368 pm In–In) in an AA stacking sequence along the c axis. The gadolinium atoms fill distorted square and pentagonal prismatic cages between these networks with strong bonding to the platinum atoms.     

Solid-phase domino syntheses of functionalized tetronates with Ph3PCCO

Domino addition-Wittig olefination reactions of α-hydroxy esters immobilized on polystyrene with Ph₃PCCO to give resin-bound tetronates proceed as readily as in solution. α-Hydroxy allyl esters can react to give either supported allyl tetronates or the corresponding Claisen-rearranged 3-allyltetronic acids, depending on conditions.     

Ammonia detection via integrated optical evanescent wave sensors

Detection of ammonia in the gas phase by means of integrated optical components, coated with sensitive films which reversibly change their spectral absorption with ammonia concentration, is demonstrated. The evanescent wave of the guided light continuously probes the absorbance of the sensor membrane at 633 nm. The output intensity is compared with that of a reference channel not influenced by the sensitive film. With Bromocresol Green and Bromophenol Blue in silicone as indicators, ammonia levels of less than 1 ppm are detectable, the dynamic range being from 1 to 200 ppm. The response depends on the relative humidity, and acidic gases including sulphur dioxide, carbon dioxide, and nitric oxides are found to reduce the relative signal change caused by ammonia, whilst in the absence of ammonia they remain inert. Aging of the film is observed within a few months after film preparation.     

Vierdimensionale Stabile Ebenen

Zusammenfassung Eine Stabile Ebene ist eine stetige Inzidenzstruktur mit eindeutig bestimmten Verbindungsgeraden zu je zwei Punkten, in der das Stabilitätsaxiom gilt: Besitzt ein Geradenpaar einen Schnittpunkt, so existiert der Durchschnitt auch für jedes genügend nah benachbarte Paar. Stabile Ebenen wurden bislang nur unter der Voraussetzung untersucht, daß der Punktraum eine Fläche ist (ebene Ebenen). Hier wird allgemeiner vorausgesetzt, daß der Punktraum lokalkompakt und von positiver Dimension ist. Es wird bewiesen, daß der Punktraum metrisierbar, lokal bogenzusammenhängend und lokal kontrahierbar ist. Das Büschel aller Geraden durch einen Punkt ist kompakt und zusammenhängend. Falls die Geraden Mannigfaltigkeiten sind, so sind die Büschel Sphären der Dimension 1, 2, 4 oder 8. Ist die Dimension der Punktmenge höchstens 4, so sind die Geraden stets Mannigfaltigkeiten. Eine stabile Ebene ist genau dann projektiv, wenn der Punktraum kompakt ist. Die Automorphismengruppe einer stabilen Ebene ist in der kompakt-offenen Topologie lokalkompakt; sie ist eine Liegruppe, falls der Punktraum R ⁴ ist.Unter der Voraussetzung, daß alle Geraden zu R ² homöomorph sind, werden folgende Aussagen bewiesen: Die Gruppe aller Kollineationen mit einem festen Zentrum wirkt frei und mit abgeschlossenen Bahnen auf dem Komplement des Zentrums; ist sie nicht kompakt, so gibt es durch das Zentrum genau eine Nichtschneidende zu jeder Geraden außerhalb. Involutorische Automorphismen sind entweder Punkt- oder Geradenspiegelungen, oder sie besitzen eine zweidimensionale Unterebene von Fixpunkten (Baer-Involutionen). An jedem Punkt und jeder Geraden gibt es höchstens eine Spiegelung. Die Dimension der Automorphismengruppe ist höchstens 12; ist sie größer als 9, so ist die Ebene affin und desarguessch. Andererseits gibt es eine nicht-affine Ebene mit 9-dimensionaler Gruppe. Fahnenhomogene Ebenen sind genau die desarguessche affine Ebene und die komplexe hyperbolische Ebene, das heißt die offene Einheitskugel der affinen Ebene mit der induzierten Struktur.     

First Observation of an Inverse Ruddlesden‐Popper Series: (A3n+1ONn−1)Bin+1 with A = Sr,Ba and n = 1, 3

Single crystals ((Ba_0.78(1)Sr_0.22)₄O)Bi₂ and ((Ba_0.62(1)Sr_0.38)₁₀N₂O)Bi₄ were successfully prepared from melt beads of Ba, Sr, and Bi in nitrogen atmosphere with oxygen impurities. The phases can be prepared in single phase from the appropriate mixtures of alkaline‐earth metal, bismuth, and bismuth oxide upon heating in pure nitrogen atmosphere. ((Ba_0.78(1)Sr_0.22)₄O)Bi₂ crystallizes in the K₂NiF₄ structure type (space group I4/mmm, No. 139, a = 522.34(5) pm, c = 1844.0(2) pm, Z = 2, R_gt(F) = 0.039) with layers of vertex‐sharing octahedra ((Ba,Sr)_4/2Ba₂O). ((Ba_0.62(1)Sr_0.38)₁₀N₂O)Bi₄ crystallizes as an isotype of Sr₄Ti₃O₁₀ (space group I4/mmm, No. 139, a = 531.3(1) pm, c = 3983.2(4) pm, Z = 2, R_gt(F) = 0.050) containing slabs of three layers of vertex‐sharing octahedra further connected via corners. These compounds are interpreted in terms of members of an inverse Ruddlesden‐Popper series with the general formula n (A₃ON_n?1)Bi · ABi or (A_3n+1ON_n?1)Bi_n+1, respectively, with n = 1, 3. Partial order of the alkaline‐earth metal ions is analyzed.