Synthesis of group 1 metal 2,6-diphenylphenoxide complexes [M(OC6H3Ph2-2,6)] (M = Li,Na, K,Rb, Cs) and structures of the solvent-free complexes [Rb(OC6H3Ph2-2,6)]x and [Cs(OC6H3Ph2-2,6)x: one-dimensional extended arrays of metal aryloxides

Reaction of 2,6-diphenylphenol (HOC(6)H(3)Ph(2)-2,6) with (n)BuLi, NaH, KH, or Rb or Cs metal in benzene gives the solvent-free complexes [M(OAr)]x in excellent yield. The complex [Rb(OC(6)H(3)Ph(2)-2,6)](x)() exhibits a ladderlike structure in the solid state with triply bridging oxygen atoms and Rb-O distances of 2.743(3), 2.930(2), and 2.973(2) A. The Rb cations interact with the pi-electron cloud of the arene moieties, giving rise to a high Rb coordination number. The cesium-containing congener forms a layered, columnlike structure consisting of [Cs(2)(mu(2)-OAr)(2)] units, with nearly identical Cs-O distances of 2.945(2) and 2.947(2) A. The individual layers are held together solely by Cs-arene pi-interactions.     

Zur Erweiterung algebraischer Strukturen durch Rechtsquotientenbildung

Ohne ZusammenfassungVorgelegt vonL. Rédei     

Extraktionsphotometrische Bestimmung von Zinn in molybdänhaltigen Stählen mit 3′-Pyridylfluoron

The steel sample is dissolved in a mixture of sulphuric acid and hydrogen peroxide. Tin is extracted as SnI₄ with benzene and determined photometrically with 3′-pyridylnuorone. 3×10^?4% of Sn can still be determined in a 1000 mg sample without interference of molybdenum. Standard deviations were within the range of ± 0.001 to ± 0.00002%.     

Vector-valued Lg-splines I. Interpolating splines

The theory of Lg-splines developed by Jerome and Schumaker is extended to the vector-valued (multivariate) case. The extension is described in the frame-work of a reproducing-kernel Hilbert space which among other things allows the establishment of a congruent least-squares estimation problem for a vectorvalued lumped random process. The results include a dynamic recursive algorithm for vector-valued Lg-splines with EHB data and a useful structural characterization theorem for such splines. Some results on computable approximation error bounds are also included.     

Dynamically stabilized growth of polar oxides: the case of MgO(111)

By using MgO(111) as a model system for polar oxide film growth, we show by first-principles calculations that H acts as a surfactant, i.e., the H changes its position and bonding during the growth process, remaining in the surface region. Continuous presence of H during the growth of MgO(111) film efficiently removes the microscopic dipole moment, thus enabling the growth of perfect fcc-ordered MgO(111) films. These theoretical predictions are confirmed experimentally by molecular beam epitaxy single crystal growth of MgO(111) on SiC(0001).     

Comparative distribution coefficients and cation-exchange behaviour of the alkaline earth elements with various complexing agents

Equilibrium distribution coefficients are presented for the alkaline earth metals Be(II), Mg(II), Ca(II), Sr(II) and Ba(II) with the complexing agents acetate, formate, lactate, citrate, tartrate, alpha-hydroxyisobutyrate, malonate, malate, acetylacetonate, EDTA, EGTA and DCTA, and the AG50W-X8 cation-exchange resin. Coefficients in HCl, HNO(3), HClO(4) and NH(4)Cl are included for the sake of completeness. The merits of the various complexing agents for the separation of adjacent element pairs are discussed and experimental elution curves are presented for selected separations. Separation factors for adjacent elements are calculated at eluting agent concentrations corresponding to a distribution coefficient of 10 for the less strongly absorbed element and are presented together with the eluting agent concentrations to form a basis for comparison.     

The influence of thiourea on the cation-exchange behaviour of various elements in dilute nitric and hydrochloric acids

Cation-exchange distribution coefficients for 21 elements between the cation-exchange resin AG50W-X4 and dilute nitric and hydrochloric acid containing up to 2.0M concentration of thiourea are presented. The ion-exchange behaviour of the elements and some possible separations are discussed. Four multi-element elution curves are presented, demonstrating the separation of the combinations Ga(Ag, Cu)Zn(Cd, Pb, In, Sn[IV]), CoPbSbTe, ZnCdBiHg, and AgCdInAu.