Browsing by Author "Blewett Gavin"

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    Synthesis, structure and coordination chemistry of new monopodal and bipodal thiocarbamic esters and acyl(aroyl)-substituted ureas with Ni(II), Pd(II), Pt(II) and Cu(II)
    (Stellenbosch : Stellenbosch University, 2006-12) Blewett Gavin; Koch, Klaus R.; Bredenkamp, M. W.; Stellenbosch University. Faculty of Science. Dept. of Chemistry and Polymer Science.
    ENGLISH ABSTRACT: N-acyl(aroyl)-N',N'-dialkylthioureas have resulted in a number of potential industrial and analytical applications within the platinum group metals (PGM) industry. N-acyl(aroyl)thiocarbamic-0-alkyl esters and N-acyl(aroyl)-N',N'-dialkylureas are remarkably similar in connectivity and molecular geometry to the N-acyl(aroyl)-N',N'-dialkylthioureas and are therefore of interest as structural analogues. A systematic study was made of the influence of variation of the N-acyl(aroyl) moiety, as well as the 0-alkyl moiety of N-acyl(aroyl)thiocarbamic-0-alkyl esters, on the coordination geometry of this class of ligand to nickel(II), palladium(II) and platinum(II). Numerous single crystal X-ray analyses were undertaken on both the non-coordinated ligands as well as the resultant complexes in order to elucidate the effect these variations have on the molecular structures and the overall crystal lattices. Particular attention was paid to the effect that these variations have in the solid state on the carbon-nitrogen bond lengths within the non-coordinated ligands as well as the derived metal complexes. A systematic study was also undertaken of the steric and electronic influences of electron rich substituents introduced onto the aroyl moiety of the N-acyl(aroyl)thiocarbamic-0-alkyl esters on the metal-oxygen bond lengths within the derived 0-alkyl-N-aroyl-thiocarbamato complexes. A parallel investigation was carried out on a series of N-acyl(aroyl)-N',N'-dialkylureas to elucidate the effect of the variation from bidentate (S, 0)-donor atoms sets to the ( 0,0 ')-donor atom sets. The molecular structures of several N-acyl(aroyl)-N',N'-dialkylureas as well as several copper(II) complexes thereof were determined and used to investigate the steric and electronic influences the N',N'-dialkyl and N-acyl(aroy) variations within this series have on the coordination of this class of ligand. The resultant scarcity of trans- or anti-( 0, 0 ') chelates was also investigated from an electronic and steric perspective of the ligands and their coordination mode to the metals investigated. The first example of a trans- or anti-( 0, 0 ') copper complex of this class of ligand was successfully isolated and fully characterised. Furthermore, the theme has been expanded to incorporate the preparation and characterisation of bipodal equivalents to the simple monopodal N-acyl(aroyl)thiocarbamic-0-alkyl esters. These bipodal compounds potentially add a 'supramolecular' and 'self assembly' dimension to the Nacyl( aroyl)thiocarbamic-0-alkyl ester motif. The first crystal structures of this type are reported and include an interesting case of polymorphism. The coordination of this class of bipodal ligand to several platinum group metals as well as copper was investigated.