Arene transition metal chemistry : III. Arene exchange phenomena

Arene exchange between free arene and an arene—transition metal complex is reviewed with respect to structure, thermodynamics, kinetics and reaction mechanism. Catalysis of such arene exchange is also examined. Experimental results are presented for arene exchange between arene and the arene—metal complexes: η⁶-arene-1,5-cyclooctadieneruthenium, the cationic η⁶-arene-1,5-cyclooctadieneiridium and η⁶-arenetricarbonylmolybdenum. Mechanistic features of these exchange reactions are discussed.     

Röntgenographische Untersuchungen und Strukturchemie von Chalkogenomolybdaten und -wolframaten. II

X-Ray Investigations and Structure Chemistry of Chalkogenomolybdates and -tungstates. II. The chalkogenomolybdates and -tungstates (NH₄)₂MoS₃Se, (NH₄)₂MoS₂Se₂, (NH₄)₂MoSSe₃, (NH₄)₂WSSe₃, Cs₂MoS₂Se, Cs₂MoS₂Se, Cs₂MoSSe₃, Cs₂WSSe₃, Cs₂MoOS₂Se, Cs₂WOS₂Se, Cs₂MoOSSe₂, and Cs₂WOSSe₂ are investigated by means of X-ray powder diffractometry. All compounds crystallize orthorhombic in spacegroup D? Pnma and are isomorphous with β-K₂SO₄. Systematic relations between lattice constants and occupation of atomic positions in the unit cell are discussed.     

A Chemical Proteomic Strategy Reveals Inhibitors of Lipoate Salvage in Bacteria and Parasites

The development of novel anti-infectives requires unprecedented strategies targeting pathways which are solely present in pathogens but absent in humans. Following this principle, we developed inhibitors of lipoic acid ( LA ) salvage, a crucial pathway for the survival of LA auxotrophic bacteria and parasites but non-essential in human cells. An LA -based probe was selectively transferred onto substrate proteins via lipoate protein ligase (LPL) in intact cells, and their binding sites were determined by mass spectrometry. Probe labeling served as a proxy of LPL activity, enabling in situ screenings for cell-permeable LPL inhibitors. Profiling a focused compound library revealed two substrate analogs ( LAMe and C3 ) as inhibitors, which were further validated by binding studies and co-crystallography. Importantly, LAMe exhibited low toxicity in human cells and achieved killing of Plasmodium falciparum in erythrocytes with an EC₅₀ value of 15 μM, making it the most effective LPL inhibitor reported to date.     

Sodium thio­phenolate N,N,N′,N′-tetra­methyl­ethyl­enedi­amine

The title compound, Na⁺·C₆H₅S⁻·C₆H₁₆N₂, forms lipophilically wrapped infinite sodium chains along the a axis. Each sodium cation is coordinated by three thio­phenolate S atoms and two N centres of one tetra­methyl­ethyl­enedi­amine molecule.     

Stress relaxation behavior of soda-lime glass between the transformation and softening temperatures

The compressive stress relaxation modulus of a container glass composition was investigated over a wide range of strain, time, modulus, and temperature. It is shown that the glass behaves in a linear viscoelastic manner up to a 2% strain level, and that the relaxation modulus is a smooth function of time, with no pseudo-rubbery plateau apparent down to a modulus of 10⁸ dyn/cm². The data cover roughly five decades of modulus, five decades of time, and a temperature range of 150° C above the glass transition, T_g = 536°C. Within experimental error, the effect of temperature on the stress relaxation behavior is to simply shift the modulus-time curves along the time axis with no change in shape. Temperature dependent shift factor data are expressed in terms of the WLF relation, and are shown to be in good agreement with data found in the literature for other silicate compositions. Viscosity data derived from the generated stress relaxation data agree well with data obtained by more direct methods.     

Operator algebras and a theorem of Dieudonne

LetA be aC*-algebra with second dualA″. Let (φ _n)(n=1,...) be a sequence in the dual ofA such that limφ _n(a) exists for eacha εA. In general, this does not imply that limφ _n(x) exists for eachx εA″. But if limφ _n(p) exists whenever p is the range projection of a positive self-adjoint element of the unit ball ofA, then it is shown that limφ _n(x) does exist for eachx inA″. This is a non-commutative generalisation of a celebrated theorem of Dieudonné. A new proof of Dieudonné’s theorem, for positive measures, is given here. The proof of the main result makes use of Dieudonné’s original theorem.     

Übergangsmetallchalkogenverbindungen. Darstellung,IR- und Raman-Spektren sowie röntgenographische Untersuchungen von Verbindungen des Typs A3(MeOS3)Cl und A2MeOS3 (A = K,Rb; Me = Mo W)

Transition Metal Chalkogen Compounds. Preparation, I.R. spectra, Raman Spectra, and X-Ray Investigations on Compounds of the Type A₃(MeOS₃)CI and A₂ MeOS₃(A = K, Rb; Me = Mo, W) The preparation, vibrational spectra, and x-ray data of compounds of the type A₃(MeOS₃)Cl and A₂MeOS₃ (A = K, Rb; Me = Mo, W) are reported. K₃(MoOS₃)Cl, K₃(WOS₃)Cl, and Rb₃(WOS₃)Cl are novel salts which can be prepared by passing H₂S through strong alcaline aqueous MoO and WO solutions containing KCl or RbCl. The salts crystallize in space group Pca2₁? C (No. 29) (Z = 4) with discrete MeOS tetrahedrons. The compounds A₂MeOS₃ (A = K, Rb; Ne = Mo, W) which are in part precipitable only by addition of organic solvents crystallize in space group Pnma? D (No. 62) with four formula units per unit cell.