الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 226 |  |  |
| | | from | 226 | | |
Abstract
preparation and characterization of the new Schiff-base, 4-hydroxysalicylidene-2-aminopyrimidine (H2sap), and its Ni(II), Cu(II), Ru(II), Rh(III), Pd(II), Ag(I) and Au(III) complexes. Physico-chemical measurements of the prepared Schiff-base (H2sap) and its reported complexes included elemental analysis, spectral (IR, 1H-NMR, 31P-NMR, electronic and mass), molar conductance, magnetic susceptibility, themal (TGA) and pH-metric measurements. IR, 1H-NMR, 31P-NMR spectral data suggest that Hsap acts as a mononegative bidentate chelating agent, coordinates the metal ions via the azomethine nitrogen (CH=N) and deprotonated 2-hydroxy centres forming six-membered chelating ring, without any participation of 4-OH in coordination. The determination of the de-protonation constants of H2sap (pKa1 = 8.5 and pKa2 = 10.2). and the formation constants of the complexes by half methods showed that the order of stability constants decreased in the order Ag(I) Pd(II) Cu(II) Ni(II) Co(II) and for the first row transition elements in accordance with Irving and Williams order. It was studied the catalytic epoxidation of some olefins by [Ru(Hsap)2(H2O)2] and its anchoring silica analogue (FSM-Ims-Ru) in presence of molecular oxygen as co-oxidant homogeneous (in CH2Cl2) and heterogeneous catalysis, respectively. The catalyst, FSM-Ims-Ru, was found to exhibit considerable increases in the catalytic efficiency and selectivity in epoxidation of olefins as well as its recoverability and reusability (heterogeneous catalysis). Schiff-base H2sap was examined as corrosion inhibitor for Cu and Ni in acidic media (0.5M HCl) by using potentio-dynamic polarization and electrochemical impedance spectroscopy (EIS). Different concentrations of H2sap were found to affect the cathodic and anodic polarization curves of Cu and Ni. The cathodic reactions on copper or nickel electrode was inhibited in presence of H2sap, which was found to affect the cathodic reaction more than the anodic one.