A convenient route to enantiomerically pure 2-substituted methyl glycerate derivatives

[reaction: see text] The lithium enolate of a butanediacetal-protected glycerate derivative undergoes efficient and diastereoselective alkylation to afford a new fully substituted stereogenic center. These compounds may be elaborated to stable 2-substituted glyceraldehyde derivatives.     

Origin of surface conductivity in diamond

Hydrogen-terminated diamond exhibits a high surface conductivity (SC) that is commonly attributed to the direct action of hydrogen-related acceptors. We give experimental evidence that hydrogen is only a necessary requirement for SC; exposure to air is also essential. We propose a mechanism in which a redox reaction in an adsorbed water layer provides the electron sink for the subsurface hole accumulation layer. The model explains the experimental findings including the fact that hydrogenated diamond is unique among all semiconductors in this respect.     

Synthesis,electrochemical properties and electro-oxidative polymerization of copper(II) and nickel(II) complexes with N′-benzoylthiourea ligands containing pyrrole groups

The synthesis of four N-benzoylthioureas containing pyrrole groups are described. The electrochemical behaviour of their copper(II) and nickel(II) complexes has been investigated in aprotic solvents by coulometry and by cyclic voltammetry which indicates that the electrochemical oxidation of copper complexes leads to the formation of Cu^II-benzylureate complexes. The oxidative polymerization of nickel complexes on platinum and a glassy carbon electrode, has been carried out in MeCN.The redox properties of the polymeric films formed have been examined by cyclic voltammetry. The films are catalytically active in the electroreduction of oxygen.     

Evidence for a localized magnetic moment in paramagnetic α-Mn from multiplet splitting

High resolution X-ray photoemission spectra of paramagnetic α-Mn are reported. The 3s and 2s levels show considerable multiplet splitting. Analysis of the 3s splitting yields a spin S ～ 1.25, implying a magnetic moment of 2.5 μ_B, in excellent agreement with a recent susceptibility value, but larger than the neutron scattering result.     

Valence and core level photoemission spectra of AlxGa1−xAs

A linear shift towards the top of the valence band with increasing Al-content was observed for all features in the valence band spectra of Al_xGa_1?xAs. The binding energies of the metallic core levels remained invariant, whereas those of As decreased with increasing Al concentration. The results are interpreted in terms of an increasing ionicity with Al content.     

The effect of spin-orbit splitting on the valence band density of states of lead

Tight-binding calculations are reported for the valence bands of lead, with and without spin-orbit splitting in the 6p bands. The addition of spin-orbit interaction is necessary to reproduce the two-peaked structure in the 6p density of states observed in X-ray photoemission, in contrast to the assertion by Breeze that crystal-field effects alone are enough. The observed splitting is, however, only fortuitously nearly equal to the atomic spin-orbit splitting. The tight-binding band structure, with spin-orbit splitting, gives better overall agreement with optical, Fermi surface, and photoemission data than did any of the three earlier band structures.