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)

Blewett Gavin (2006-12)

Thesis (PhD)--Stellenbosch University, 2006.

Thesis

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.

AFRIKAANSE OPSOMMING: N'-asiel(aroi'el)-N',N'-Dialkieltioureums toon potensiaal in verskeie bedryfs en analitiese toepassings in die platinumgroep (PGM) metaalbedryf. N-Asiel(aro'iel)tiokarbamaat 0-alkiel esters is aansienlik eenders in konnektiwiteit en molekutere struktuur aan N-asiel(aroi'el)-N,N-dialkieltioureums en is om daardie rede van belang as strukturele analoe van die relatief welbestudeurde en -bekende Nasiel( aro'iel)-N ',N '-dialkieltioureums. 'n Sistematiese ondersoek na die invloed van die variering van die N-asiel(aro'iel)-groep is ondergaan, asook die 0-alkiel groep van N-asiel(aroi'el)tiokarbamaat 0-alkiel esters, op die ko-ordinerings geometrie van hierdie klas van ligande aan nikkel(II), palladium(II) en platinum(IJ). Verskeie enkelkristal X-straal analises is onderneem op beide die ongeko-ordineerde ligande sowel as die gevolglike komplekse, om vas te stel wat die uitwerking is van die veranderlikes op molekulere struktuur asook die kristal roosters in die geheel. Spesifieke aandag is geskenk aan die effek wat die veranderlikes het in die vaste toestand op die koolstof-stikstof bindingslengtes in die ongekoordineerde ligandes asook die metaalkompleks afgeleides. 'n Sistematiese studie is ook onderneem van die steries en elektroniese invloed van elektronryk substituente wat aan die aro'iel groep van die Nasiel( aro'iel)tiokarbamaat 0-alkiel esters aangebring is op die metal-suurstof-bindingslengte in die afgeleide 0-alkiel-N-aroi'eltiokarbamato-komplekse. 'n Paralelle ondersoek is uitgevoer op 'n reeks N-asiel(aroi'el)-N',N'-dialkielureums om die uitwerking van die variasie van die bidentate (S,0)-donoratoom stelle na (0,0)-donoratoom stele te bepaal. Die molekulere strukture van verskeie N-asiel(aro'iel)-N',N'-dialkielureums asook verskeie koper(II)komplekse van hulle was onderneem en gebruik om die steriese en elektroniese invloed wat die N',N'dialkiel- en N-asiel(aroi'el)-veranderlikes binne die reeks het of die ko-ordinasie van hierdie klas van, ligand. Die gevolglike tekort van die trans- of anti-(0,0')-chelate is ook ondersoek vanuit 'n steriese en elektroniese perspektief van die ligande en hulle tipe ko-ordinasie aan die metale wat ondersoek is. Die eerste voorbeeld van 'n trans- of anti-(0,0')-koperkompleks van hierdie ligande klas is met welslae gei'soleer en ten voile gekarakteriseer. Die tema is verdermeer uitgebrei om die bereiding en karakterisering van due bipodale ekwivalente van die eenvoudige monopodale N-asiel(aroi'el)tiokarbamaat 0-alkiel esters in te sluit. Hierdie bipodale verbindings het die potensiaal om 'n 'supramolekulere' en 'self-samestellende' dimensie aan die Nasiel( aro'iel)tiokarbamaat 0-alkiel esters motief te verleen. Die eerste kristalstrukture van hierdie tipe word hier vermeld en sluit 'n interessante geval van polimorfisme in. Die ko-ordinasie van hierdie klas van bipodale ligand aan verskeie platinumgroep metale asook koper is ondersoek.

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