The cationic cluster Grignard [{MgCl(thf)2}3(mu3-C3H5)2]+

The synthesis and structure of [{MgCl(thf)2}3(mu3-C3H5)2]2[Mg(C3H5)4], which contains both a cationic cluster Grignard and a tetraorganomagnesiate dianion, are reported.     

Development of a novel, highly efficient halide-catalyzed sulfenylation of indoles

[reaction: see text] The reaction of a variety of indoles with N-thioalkyl- and N-thioarylphthalimides to produce 3-thioindoles is reported. Catalytic quantities of halide-containing salts are crucial to the success of this reaction. This highly efficient reaction provides sulfenylated indoles from bench-stable, readily available starting materials in good to excellent yields.     

A new Co(II) coordination solid with mixed oxygen, carboxylate, pyridine and thiolate donors exhibiting canted antiferromagnetism with T(C) approximately 68 K

Reaction of Co(II) chloride with the sodium salt of 2-mercaptonicotinic acid in water at 200 degrees C results in the formation of Co4(2-mna)4(H2O), which orders as a canted antiferromagnet at 68 K.     

On the mechanism of an asymmetric alpha,beta-unsaturated carboxylic acid hydrogenation: application to the synthesis of a PGD2 receptor antagonist

Ruthenium complexes employing axially chiral ligands were found to be effective asymmetric hydrogenation catalysts for the reduction of alpha,beta-unsaturated ene acid 1-E to give 2, a prostaglandin D2 (PGD2) receptor antagonist. With [(S-BINAP)Ru(p-cymene)Cl2]2 (3, S-BINAP = (S)-(+)-2,2'-bis(diphenylphospino)-1,1'-binapthyl), it was discovered that low hydrogen pressures (<30 psi) were essential to achieve high enantioselectivities (92% ee). A detailed mechanistic study was undertaken to elucidate this pressure dependence. It was determined that compound 1-E is in a ruthenium-catalyzed equilibrium with endocylic isomer 1-Endo and in photochemical equilibrium with Z isomer 1-Z. Each isomer could be hydrogenated to give 2, albeit with different rates and enantioselectivities. Hydrogenation of 1-Endo with 3 was found to give 2 in high enantiomeric excess, regardless of pressure and at a rate substantially faster than that of hydrogenation of 1-E and 1-Z. In contrast, isomers 1-E and 1-Z exhibited pressure-dependent enantioselectivities, with higher enantiomeric excesses obtained at lower pressures. A rationale for this pressure dependence is described. Deuterium labeling studies with 1-Endo and tiglic acid were used to elucidate the mechanism of hydride insertion and product release from ruthenium. Under neutral conditions, protonolysis was the major pathway for metal-carbon cleavage, while under basic conditions, hydrogenolysis of the metal-carbon bond was predominant.     

On the Deformation of the Circumflex Coronary Artery During Inflation Tests at Constant Length

Here we investigate whether the deformation observed in an experiment in which the porcine circumflex coronary artery is subjected to inflation at constant length included in the class, , , . We find that this is not the case and discuss its implications in the study of the mechanics of this artery. Moreover, we identify and quantify the uncertainty in the value of the invariants of the left Cauchy–Green tensor inferred from the 2D motion of markers affixed to the surface of the test specimen, and suggest that 3D tracking of markers is needed due to inherent bending and twisting induced by pressurization in vitro.     

Oxyphyllones A and B,novel sesquiterpenes with an unusual 4,5-secoeudesmane skeleton from Alpinia oxyphylla

Two novel 4,5-secoeudesmane sesquiterpenoids,oxyphyllones A(1) and B(2) were isolated from the fruits of Alpinia oxyphylla.Their structures were established by spectroscopic methods including 1D and 2D NMR spectra.These two compounds are the first example of naturally occurring sesquiterpenoids with a 4,5-secoeudesmane skeleton in the family of Zingiberaceae and oxyphyllone A(1) is the first 4,5-secoeudesmane type of 13-norsesquiterpenoid.Compounds 1 and 2 exhibited no cytotoxicities against three cancer...     

Ultrashort Phase-Matching Wavelength and Strong Second-Harmonic Generation in Deep-UV-Transparent Oxyfluorides by Covalency Reduction

The development of urgently-needed ultraviolet (UV)/deep-UV nonlinear optical (NLO) materials has been hindered by contradictory requirements of the microstructure, in particular the need for a strong second-harmonic generation (SHG) response as well as a short phase-matching (PM) wavelength. We herein employ a “de-covalency” band gap engineering strategy to adjust the optical linearity and nonlinearity. This has been achieved by assembling two types of transition-metal (TM) polyhedra ([TaO₂F₄] and [TaF₇]), affording the first tantalum-based deep-UV-transparent NLO materials, A₅Ta₃OF₁₈ (A = K (KTOF), Rb (RTOF)). Experimental and theoretical studies reveal that the highly ionic bonds and strong electropositivity of tantalum in the two oxyfluorides induce record short PM wavelengths (238 (KTOF) and 240 (RTOF) nm) for d⁰-TM-centered oxides, in addition to strong SHG responses (2.8 × KH₂PO₄ (KTOF) and 2.6 × KH₂PO₄ (RTOF)), and sufficient birefringences (0.092 (KTOF) and 0.085 (RTOF) at 546 nm). These results not only broaden the available strategies for achieving deep-UV NLO materials by exploiting the currently neglected d⁰-TMs, but also push the shortest PM wavelength into the short-wavelength UV region.     

Giant Mid-Infrared Second-Harmonic Generation Response in a Densely-Stacked Van Der Waals Transition-Metal Oxychloride

Second-harmonic generation (SHG) is a fundamental optical property of nonlinear optical (NLO) crystals. Thus far, it has proved difficult to engineer large SHG responses, particularly in the mid-infrared region, owing to the difficulty in simultaneously controlling the arrangement and density of functional NLO-active units. Herein, a new assembly strategy employing functional modules only, and aimed at maximizing the density and optimizing the spatial arrangement of highly efficient functional modules, has been applied to the preparation of NLO crystals, affording the van der Waals crystal MoO₂Cl₂. This exhibits the strongest powder SHG response (2.1×KTiOPO₄ (KTP) @ 2100 nm) for a transition-metal oxyhalide, a wide optical transparency window, and a sufficient birefringence. MoO₂Cl₂ is the first SHG-active transition-metal oxyhalide effective in the infrared region. Theoretical studies and crystal structure analysis suggest that the densely packed, optimally-aligned [MoO₄Cl₂] modules within the two-dimensional van der Waals layers are responsible for the giant SHG response.