Browsing by Author "Burger, M. R. (Marga Retha)"

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    Condensed phase properties of platinum group metal complexes from computational simulations
    (Stellenbosch : University of Stellenbosch, 2004-04) Burger, M. R. (Marga Retha); Koch, K. R.; Naidoo, K.; University of Stellenbosch. Faculty of Science. Dept. of Chemistry and Polymer Science.
    ENGLISH ABSTRACT: A variety of computational techniques are used to calculate structural, thermodynamic and transport properties of two specific Platinum Group Metal (PGM) complex systems. The first system consists of a PGM complex ([PdCl4]2-; [PtCl4]2-; [PtCl6]2- or [RhCl6]3-) with sodium counter-ions in a water solution at 30ºC and at a concentration of 0.106 mol/dm3. The second system under consideration is that of a PGM complex ([PdCl4]2-; [PtCl4]2-; [PtCl6]2- or [RhCl6]3-) with sodium counter-ions in a water solution in the presence of four poly (ethylene oxide) (PEO) chains at 30ºC and at a concentration of 0.013 mol/dm3. A conformational study of the two types of dihedral angles in a PEO chain (-C-O-C-Cand -O-C-C-O-) is performed and the extreme flexibility of the polymer is confirmed. Dihedral angle distributions of the two dihedral angles are calculated and explained in terms of the potential energy surface obtained from the conformational study. The solvation geometries of the PGM complexes are confirmed and the results are contrasted with those in the system where the polymer (PEO) is present. It is concluded that the effect of the polymer on the structure and degree of solvation is negligible. The free energy of solvation values of the PGM complexes are calculated to provide insight into their structural characteristics such as solvation shell volume and geometry. The structural and thermodynamic properties of the PGM complexes in solution are also used to explain the trends observed in the calculated diffusion coefficients. Comments are made on the accuracy of the calculated diffusion coefficients as well as the legitimacy of the mechanistic speculations which results from them. Suggestions regarding possible future improvements to the computational methods are made.