Addition of arenes to ethylene and propene catalyzed by ruthenium

TpRuII(CO)(Me)(NCMe) (Tp = hydridotris(pyrazolyl)borate) serves as a catalyst precursor for the conversion of benzene and ethylene or propene to alkylaromatic products. The reaction proceeds via the formation of the active catalyst TpRu(CO)(Ph)(NCMe) and is mildly selective for linear propylbenzene over isopropylbenzene.     

The Preparation, Characterization and X-ray Structural Analysis of Tetrakis[1-Methyl-3-(2-Propyl)-2(3H)-Imidazolethione]Cadmium(II) Hexafluorophosphate

Abstract  A new compound, [Cd(mipit)₄][PF₆]₂ has been synthesized and characterized via standard solid and solution state methods including single crystal X-ray crystallography (mipit = 1-methyl-3-(2-propyl)-2(3H)-imidazolethione). The title compound crystallizes in tetragonal space group I4 ₁ /a with a = 12.478(2) ?, b = 12.478(2) ?, c = 28.806(6) ?, and Z = 4. The complex is a high melting, colorless solid that has a distorted tetrahedral CdS₄ coordination geometry. Thermogravimetric analysis results for the title compound as well as for another potential CdS synthon and two potential CdSe synthons are reported. Graphical Abstract  The synthesis and characterization of the title compound, a new ionic homoleptic cadmium complex, tetrakis[1-methyl-3-(2-propyl)-2(3H)-imidazolethione]cadmium(II) hexafluorophosphate is reported. The results of a single crystal X-ray diffraction analysis reveal a distorted tetrahedral CdS₄ coordination sphere about the cadmium. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The Structure and Thermal Stability of 1,2-Dimethoxycarbonyl-3,3-dimethylcyclopropene

The X-ray crystal structure of 1,2-dimethoxycarbonyl-3,3-dimethylcyclopropene (1) is reported and the geometry is contrasted to that of cyclopropene (2) and 3,3-dimethylcyclopropene (3). Ab initio and density functional theory calculations were carried out in order to examine the conformational preference of the ester groups (i.e., s-cis vs. s-trans) and to probe the thermal stability of 1 via a model compound, 1-methoxycarbonyl-3-methylcyclopropene. Experimental activation parameters for the unimolecular isomerization were measured and compared to an analogous dibenzoylcyclopropene derivative.     

Monitoring of benzylpenicillin decomposition in gastric contents by capillary zone electrophoresis.

A method has been developed to follow the decay of the antibiotic penicillin, specifically penicillin G or benzylpenicillin, in the gastric contents of laboratory rats. Purification by centrifugation and DEAE cellulose treatment of the stomach contents (diluted with pH 9 phosphate-borate buffer) was sufficient to allow the quantification of penicillin by capillary zone electrophoresis. An internal standard was used to minimize the injection error. The loss of activity was greater in fasted animals, as expected from the lower pH of their gastric contents, than in fed rats. The in vivo kinetics of the decomposition of the antibiotic was compared to that obtained in water and in hydrochloric acid solutions.     

Effect of substitution of Ce on superconducting properties of Bi1.7Pb0.3Sr2Ca2−x Ce x Cu3O10+δ system

We have investigated the superconducting properties of the Bi_1.7 Pb_0.3Sr₂Ca_2−xCe _x Cu₃O_10+δ system with x=0.00, 0.02, 0.04, 0.08 and 0.1 by X-ray diffraction and magnetic susceptibility. The substitution of Ce for Ca has been found to drastically change the superconducting properties of the system. X-ray diffraction studies on these compounds indicate decrease in the c-parameter with increased substitution of Ce at Ca site and volume fraction of high T _c (2 : 2 : 2 : 3) phase decreases and low T _c phase increases. The magnetic susceptibility of this compound shows that the diamagnetic on set superconducting transition temperature (onset) varies from 109 K to 51 K for x=0.00, 0.02, 0.04, 0.08 and 0.1. These results suggest the possible existence of Ce in a tetravalent state rather than a trivalent state in this system; that is, Ca²⁺ → Ce⁴⁺ replacement changes the hole carrier concentration. Hole filling is the cause of lowering T _c of the system.     

Determination of streptomycin in pharmaceutical preparations by gas chromatography

The antibiotic streptomycin can be reliably quantitated in injectable pharmaceuticals by GC. The manipulations are not difficult, and total analysis time for duplicate samples is less than twenty minutes. Reaction of the drug with aqueous sodium hydroxide solution generates maltol, which is extracted into chloroform prior to silylation. The silyl ether of maltol is then assayed, using naphthalene as internal standard. Duplicate analyses of twenty pharmaceutical samples showed a relative standard deviation of ±1.3%.     

Self-assembled growth of nanostructural Ge islands on bromine-passivated Si(111) surfaces at room temperature

We have deposited relatively thick (∼60 nm) Ge layers on Br-passivated Si(111) substrates by thermal evaporation under high vacuum conditions at room temperature. Ge has grown in a layer-plus-island mode although it is different from the Stranski-Krastanov growth mode observed in epitaxial growth. Both the islands and the layer are nanocrystalline. This appears to be a consequence of reduction of surface free energy of the Si(111) substrate by Br-passivation. The size distribution of the Ge nanoislands has been determined. The Br-Si(111) substrates were prepared by a liquid treatment, which may not produce exactly reproducible surfaces. Nevertheless, some basic features of the nanostructural island growth are reasonably reproducible, while there are variations in the details of the island size distribution.     

The preparation, characterization and X-ray structural analysis of tetrakis[1-methyl-3-(2-propyl)-2(3H)-imidazolethione]zinc(II) tetrafluoroborate and tetrakis[1-methyl-3-(1-butyl)-2(3H)- imidazolethione]zinc(II) tetrafluoroborate

Two compounds, [Zn(mipit)₄][BF₄]₂ (1) and [Zn(mnbit)₄][BF₄]₂ (2) have been synthesized and characterized via standard solid and solution state methods including single crystal X-ray crystallography (mipit: 1-methyl-3-(2-propyl)-2(3H)-imidazolethione and mnbit: 1-methyl-3-(1-butyl)-2(3H)-imidazolethione). Compound 1 crystallizes in monoclinic space group P2₁/n with a = 11.804(2) ?, b = 16.710(3) ?, c = 25.763(5) ?, γ = 90.14(3)° and Z = 4, whereas compound 2 crystallizes in tetragonal space group $${\rm I}\bar{4}$$ with a = b = 11.6517(16) ?, c= 16.820(3) ?, and Z = 2. Both complexes are high melting, colorless water soluble 2:1 electrolyte solids that state have flattened tetrahedral ZnS₄ coordination geometry. The isopropyl analog is slightly more distorted than the n-butyl analog, and the degree of distortion is not directly related to the steric bulk of the ligand.