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)

[摘要] 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-alkylesters 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 studywas also undertaken of the steric and electronic influences of electron rich substituents introduced ontothe aroyl moiety of the N-acyl(aroyl)thiocarbamic-0-alkyl esters on the metal-oxygen bond lengthswithin 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 theeffect of the variation from bidentate (S, 0)-donor atoms sets to the ( 0,0 ')-donor atom sets. Themolecular 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 theN',N'-dialkyl and N-acyl(aroy) variations within this series have on the coordination of this class ofligand. The resultant scarcity of trans- or anti-( 0, 0 ') chelates was also investigated from an electronicand steric perspective of the ligands and their coordination mode to the metals investigated. The firstexample 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 ofbipodal equivalents to the simple monopodal N-acyl(aroyl)thiocarbamic-0-alkyl esters. These bipodalcompounds 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 andinclude an interesting case of polymorphism. The coordination of this class of bipodal ligand to severalplatinum group metals as well as copper was investigated.

[发布机构] Stellenbosch University