Initial state and transition state solvation effects in the cobaltitungstate oxidation of iodide in binary aqueous solvent mixtures

Summary Rate constants are reported for 12-tungstocobaltate(III) [CoW₁₂O₄₀]^5– oxidation of iodide in water and in binary aqueous solvent mixtures containing up to 40% methanol, 40% acetonitrile, or 60% dimethyl sulphoxide. From these kinetic results, solubility measurements on potassium 12-tungstocobaltate(III), and published data on Gibbs free energies of transfer of appropriate ions, it has been deduced that the dominant factor in determining the marked decrease in rate observed on going from water into the binary aqueous solvent mixtures is destabilisation of the transition state for the electron-transfer reaction.     

Vibrational spectroscopy at very high pressures. Part 35.1 A Raman study of K2M(CN)4, (M = Zn,Cd, Hg)

Each of the complex cyanides K₂M(CN)₄, (M = Zn, Cd, Hg), shows two high pressure first-order phase transitions which have been characterized using Raman spectroscopy. The phase changes are at 1.5 and 8.5 kbar for M = Hg, 3 and 8 kbar for M = Cd, and 4 and 14 kbar for M = Zn. It is concluded that, for each material, phase II has the trigonally-distorted spinel structure of room temperature Rb₂Hg(CN)₄, whilst phase III is probably of the hausmanite type (a tetragonally-distorted spinel).     

Crystal structures of high-valent transition-metal chalcogenide fluorides

The structures of high-valent transition-metal chalcogenide fluorides are of interest since it is not clear whether they will be related to those of their oxide-fluoride analogues or to those of the transition-metal chalcogenide chlorides and bromides. This will depend on the extent to which substitution of fluorine for chlorine or bromine or sulphur, or selenium for oxygen has the more significant effect.The first single-crystal structure on a compound of this class, WSF₄, shows that it consists of octahedrally coordinated tungsten atoms linked by cis-bridged fluorine atoms into polymeric chains. This, together with work on the structure of ReSF₄, suggests that the tendency is to follow oxide-fluoride and fluoride structures.     

Resolution of N-benzyl-N-(1,2-dihydro-2-oxoquinolin-1-yl)glycine

The $\text{N}$$\text{N}$ chiral axis in the title glycine derivative has allowed its resolution into enantiomers: the barrier Δ G^≠ for racemisation (rotation around the $\text{N}$$\text{N}$ bond) is 26.2 Kcal mol^?1.     

Partial molal volumes for iron(II)-diimine complexes in water and in aqueous methanol

Summary Partial molal volumes of the perchlorate or chloride salts of several tris-diimine-iron(II) cations have been determined in aqueous and methanol-water solutions by vibrating-tube densimetry. Partial molal volumes of the cations at infinite dilution have been estimated for aqueous solution, and compared with values for related cations. Trends of limiting partial molal volumes for perchlorate salts in methanol-water media are compared with trends in transfer chemical potentials for the respective cations; both are discussed in terms of ligand-dependent preferential solvation behaviour.     

Calculation of MEED intensities in the 5–10 keV electron energy range

A method for computing MEED intensities in the 5–10 keV electron energy range is described. The method is based on improving the computational efficiency of a RHEED program so that it can be used to handle the larger matrices involved in MEED calculations. As an example of its use rocking curves are computed for 5 keV electrons incident on the Al(110) surface in the 11?0 azimuth. Further numerical results are then presented to show that smaller scale calculations, in which only beams in the zeroth Laue zone are taken into account, can give a useful approximation to the exact rocking curves. Finally, the conditions under which these calculations are likely to be valid are discussed.     

A unified framework for the numerical solution of general quadratic matrix equations

^** Email: vassilios.tsachouridis{at}ieee.org^*** Email: N.karcanias{at}city.ac.uk^**** Email: ixp{at}le.ac.uk Algebraic quadratic equations are special cases of a singlegeneralized algebraic quadratic matrix equation (GQME). Thispaper focuses on the numerical solution of the GQME using probability-1homotopy methods. A synoptic review of these methods and theirapplication to algebraic matrix equations is provided as background.A large variety of analysis and design problems in systems andcontrol are reported as special cases of the presented frameworkand some of them are illustrated via numerical examples fromthe literature.     

Total syntheses of conformationally locked difluorinated pentopyranose analogues and a pentopyranosyl phosphate mimetic

Trifluoroethanol has been elaborated, via a telescoped sequence involving a metalated difluoroenol, a difluoroallylic alcohol, [2,3]-Wittig rearrangement, and ultimately an RCM reaction and requiring minimal intermediate purification, to a number of cyclooctenone intermediates. Epoxidation of these intermediates followed by transannular ring opening or dihydroxylation, then transannular hemiacetalization delivers novel bicyclic analogues of pentopyranoses, which were elaborated (in one case) to an analogue of a glycosyl phosphate.     

Role of three-body interactions in formation of bulk viscosity in liquid argon

With the aim of locating the origin of discrepancy between experimental and computer simulation results on bulk viscosity of liquid argon, a molecular dynamic simulation of argon interacting via ab initio pair potential and triple-dipole three-body potential has been undertaken. Bulk viscosity, obtained using Green-Kubo formula, is different from the values obtained from modeling argon using Lennard-Jones potential, the former being closer to the experimental data. The conclusion is made that many-body inter-atomic interaction plays a significant role in formation of bulk viscosity.