Crystal growth and structure determination of barium rhodates: stepping stones toward 2H-BaRhO3

Single crystals of two new barium rhodates were grown from a molten potassium carbonate flux. The new rhodates, Ba(11)Rh(10)O(30) and Ba(32)Rh(29)O(87), are structurally related to the 2H-hexagonal perovskite structure and are characterized by pseudo one-dimensional chains of alternating face-sharing trigonal prisms and octahedra. The structures of Ba(11)Rh(10)O(30) and Ba(32)Rh(29)O(87) were solved using the 4D superspace group approach in Jana2000. Ba(11)Rh(10)O(30), with a repeat of nine RhO(6) octahedra followed by one RhO(6) trigonal prism, contains the longest chain sequence of face-sharing octahedra known for this 2H-perovskite related family of oxides. A structural analysis of these two compounds revealed clear trends in metal-metal distances and octahedral heights not previously identified for this family of oxides. The application of these trends toward the structure of the all-octahedra-containing end member of the structural series, the hypothetical 2H-BaRhO(3), enabled a prediction of its rhodium-rhodium distance, octahedral height, and lattice parameters.     

Novel task-specific ionic liquid [Et2NH(CH2)2CO2H][AcO] as a robust catalyst for the efficient synthesis of some pyran-annulated scaffolds under solvent-free conditions

Research on Chemical Intermediates - A novel task-specific ionic liquid, 2-carboxy-N,N-diethylethanaminium acetate denoted as [Et2NH(CH2)2CO2H][AcO], is prepared in an easy process and fully...     

Effect of annealing temperature on hardness, thickness and phase structure of carbonitrided 304 stainless steel

Carbonitriding of AISI 304 austenitic stainless steel was performed at a plasma-processing power of 450 W using inductively coupled radio frequency (rf) plasma in a gas mixture of 50% N₂ and 50% C₂H₂. The rate of carbonitriding, microhardness, phase structure of the compound layer, surface microstructure and cross-section morphology were studied before and after the annealing process. At the annealing temperature up to 800°C, the microhardness values of the compound zones decrease, while the associated values of the diffused zones increase. Little change was found in the thickness of the compound and diffused zones when the carbonitrided samples were annealed up to 400°C. However, at a higher annealing temperature, the thicknesses of both zones increase. The γ-Fe austenite is the main crystalline phase that can be detected by X-ray diffraction. As the annealing temperature increases up to 500°C, X-ray spectra show α-Fe and Fe₅C₂ phases. Nitrogen diffuses more deeply from the near surface to the interior of the treated sample as the annealing temperature increases up to 800°C and this might explain the extent of carbonitrided thickness and the enhanced microhardness of the diffused zone.     

Synthesis of 2-boryl-1,3-butadienes from tributylphosphine stabilized zirconacyclopropenes and alkynes

Boryl zirconacycopropenes stabilized with tributylphosphine react with alkynes (terminal and internal) to give predominately 2-boryl-1,3-butadienes, 5, in 40-81% isolated yields. Products 5 are accompanied by 4-boryl-1,3-butadienes in 7-23% when terminal alkynes are inserted. However, the use of an internal alkyne (3-hexyne) gave predominantly 6c.     

Novel addition reactions of titanacycle phosphonates by tuning of Ti(O-i-Pr)4/2i-PrMgCl

Di- or tri-substituted vinylphosphonates, 2-5, can be obtained in a highly regio- and stereoselective manner from 1-alkynylphosphonates, by manipulation of Ti(O-i-Pr)4/2i-PrMgCl.     

Surface observation of solvent-impregnated Nafion membrane with atomic force microscopy

Surface morphology modification of the Nafion 117 membrane has been investigated by atomic force microscopy. The effects of water and methanol on the topography and structure of the surface were studied using the contact and tapping atomic force microscopy modes. Nafion topography considerably changes when samples absorb water. However, samples stored in methanol are characterized by flat surfaces. Surface modification was linked to an expansion phenomenon during the swelling of Nafion by solvents. Tapping-mode phase images showed that ionic and cluster domains are distinguishable from the surface of samples impregnated either in water or methanol.     

Indium tellurium trioxide chloride,InTeO3Cl

The new oxy­chloride InTeO₃Cl was synthesized from a mixture of In₂O₃, InCl₃ and TeO₂. Its structure has been determined from single‐crystal X‐ray diffraction data. The structure is composed of layers separated by a van der Waals gap. The layers consist of edge‐sharing chains of [InO₄Cl₂] octahedra linked through [TeO₃] trigonal pyramids. No free Cl atoms are located between the layers.     

One-pot easy conversion of Baylis-Hillman adducts into carbamates of unsaturated β-amino acids

An easy, one-pot transformation of Baylis-Hillman adducts into carbamates of unsaturated β-amino acids, for example, 2-(aryl(methoxycarbonylamino)methyl)acrylic acid methyl esters 7 and 2-(methoxycarbonyl aminomethyl)-3-arylacrylic acid methyl esters 8 via reaction with the Burgess reagent is described.     

Growth of Sr6Rh5O15 single crystals from high-temperature solutions: structure determination using the traditional 3-D and the 4-D superspace group methods and magnetic measurements on oriented single crystals

Single crystals of Sr6Rh5O15 were grown from a molten potassium carbonate flux. The structure was solved by both the traditional 3-D crystallographic approach and the 4-D superspace group approach using JANA2000. Both methods produced an equivalent structure determination, thereby confirming the 4-D superspace group approach as an effective structure solution method for 3-D commensurate composite structures. Sr6Rh5O15 corresponds to the n = 1, m = 1 member of the A3n+3mA'nB3m+nO9m+6n family of 2H hexagonal perovskite-related oxides. This compound is characterized by pseudo-one-dimensional polyhedral chains of four face-sharing RhO6 octahedra followed by one RhO6 trigonal prism. These chains in turn are separated by [Sr](infinity) chains. Magnetic measurements were carried out on oriented single crystals, and a very large magnetic anisotropy in the magnetic susceptibility was observed.