Yb8Ge3Sb5, a metallic mixed-valent Zintl phase containing the polymeric 1 infinity[Ge3 4-] anions

Yb8Ge3Sb5 is a nonclassical Zintl phase with metallic properties arising from the electropositive "spectator" cations of Yb. This compound contains the new Zintl anion 1infinity(Ge3)4- and is stabilized via a combination of Yb2+ and Yb3+ ions.     

V2Al5Ge5: first ternary intermetallic in the V-Al-Ge system accessible in liquid aluminium

The intermetallic compound V2Al5Ge5 grown from Al flux is reported. V2Al5Ge5: orthorhombic, Cmcm, a = 5.4072(10), b = 12.978(2), and c = 11.362(2) A, the structure features distorted pentagonal prismatic columns defined by Al and Ge atoms. Vanadium atoms occupy the central axis of columns forming a chain with long-short alternation of V-V bonds. This compound is resistant to air oxidation up to 500 degrees C.     

Quinolinium Dichromate Oxidation of Diols: A Kinetic Study

Quinolinium dichromate (QDC) in water oxidizes vicinal and nonvicinal diols to the corresponding alpha-hydroxy carbonyl compound. The rate is proportional to the concentrations of diol, oxidant and hydrogen ions, and the reactions proceed almost twice as fast in D(2)O than in H(2)O. These data can be correlated with a mechanistic pathway involving the intermediate formation of a chromate ester, which undergoes decomposition to give the product.     

Kinetics of the Oxidative Cleavage of α-Keto Acids by Quinolinium Bichromate

Reaction rates for the quinolinium dichromate oxidation of -ketoacids (pyruvic and phenylpyruvic) are determined and discussed with reference to ketoacid hydration equilibria. The rate of the reaction is dependent on the first powers of the concentrations of each (substrate, oxidant, and acid). The effect of variations in solvent composition (water-dimethylformamide mixtures) and temperature are studied. The effect of solvent is analyzed. The mechanistic pathway involves the rate-determining step of oxidative decomposition of the chromate ester of the hydrated form of the -ketoacids and oxidative decarboxylation and a simultaneous cleavage of the carbon–carbon bond.     

Electronic structure of substitutional defects and vacancies in GaSe

We have investigated the nature of defect states associated with substitutional impurities (Cd, In, Sn) and both Ga and Se vacancies in GaSe using ab initio electronic structure methods within density functional theory. These calculations were done using supercell model allowing for internal atomic relaxation. Binding energies (BEs) of defects obtained in this model are compared with effective mass approximation results. Significant central cell corrections are present for most of the defects. This is consistent with charge densities associated with the defect states that show clearly their strongly localized nature. Because of the difficulties associated with LDA/GGA in giving the correct band gap in semiconductors, we have only compared the acceptor BEs with available experiments. Our theoretical results agree well with the experiment for Cd_Ga and V_Ga. The fundamental role played by the Ga dimers in the formation of defect states is discussed.