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dc.contributor.advisorRoodt, Andreas
dc.contributor.advisorBrink, Alice
dc.contributor.authorPretorius, Carla
dc.date.accessioned2016-02-18T09:39:48Z
dc.date.available2016-02-18T09:39:48Z
dc.date.issued2015-07
dc.identifier.urihttp://hdl.handle.net/11660/2325
dc.description.abstractThis study focussed on the investigation of different β-diketonato ligands in coordination to rhodium(I). Square planar [Rh(O,O’-Bid)(CO)2] complexes have been shown to effectively facilitate metallophilic interactions between rhodium(I) centres in the construction of infinite one- dimensional metal chains in the solid-state. The classification of these systems as forming nano- wired assemblies has led to similar systems finding wide application in electronic and optical technologies. The study was focused on investigating the effect of an altered rhodium(I) environment on the metallophilic interactions and subsequent one-dimensional chains formed in the solid-state. These modifications were initiated by using a range of different coordinating β-diketonato ligands to induce either electronic or steric changes to the rhodium(I) centre. To this end, a range of rhodium(I) complexes were synthesized and characterized by IR, UV/Vis and NMR spectroscopy. Single crystal X-ray diffraction was used in the solid-state structure determinations of these complexes showing significant changes in the Rh···Rh distances in each rhodium(I) complex. It also provided valuable information with regards to how the molecules are arranged along these one-dimensional chains. Rh···Rh distances ranging from 3.134(3) Å to 3.617(3) Å were found in the solid-sate for the range of rhodium(I) complexes with the distances correlating to the UV/Vis absorption profile of each complex. A preliminary substitution reaction and equilibrium study was undertaken to further evaluate how changes at the rhodium(I) centre could affect the reactivity of the rhodium(I) complexes. An important equilibrium was shown to participate in the reaction using 31P NMR and UV/Vis spectroscopy. In this investigation it was seen that using second-order rate constants to describe the reactivity of the complexes correlated to the pKa values of the uncoordinated β-diketone ligands with an increased rate in substitution associated with a lower pKa of the free ligand. 103Rh NMR chemical shifts of the rhodium(I) complexes were also found to correlate to the pKa values of the free ligands as well as highlighting the electronic environment experienced by the metal centre. This provided an effective measure of how electronic changes to the rhodium(I) centre could affect the Rh···Rh interactions of the solid-state structures as well as the physical properties of the compounds. The study concluded with a comparison of all the parameters by which the rhodium(I) complexes were evaluated to assess how changes induced by using different coordinating β-diketonato ligands influence the one-dimensional chains constructed via metallophilic interactions as well as physical properties such as the colour exhibited by the bulk material. These parameters included pKa, UV/Vis absorbance properties, IR, 103Rh NMR, reactivity (k12 constants), Rh···Rh distances and the torsion angles of the assembled molecules.en_ZA
dc.description.abstractAfrikaans: Hierdie studie het gefokus op die ondersoek van β-diketonato ligande wat aan rodium(I) gekoördineer is. Daar is bewys dat vierkantig planêre [Rh(O,O’-Bid)(CO)2] komplekse effektief die metalofiliese interaksies tussen rodium(I) kerne in die konstruksie van oneindigende een- dimensionele metaalkettings in die vaste toestand kan fasiliteer. Die klassifikasie van hierdie stelsels om nanodraadsamestellings te vorm het gelei tot soortgelyke stelsels wat wye toepassing in elektroniese en optiese tegnologië gevind het. Die studie het gefokus op die ondersoek van die effek van `n veranderde rodium(I) omgewing op die metalofiliese interaksies en die opeenvolgende een-dimensionele kettings wat in die vaste toestand gevorm is. Hierdie veranderinge is geïnisieer deur `n reeks verskillend koördinerende β-diketonato ligande te gebruik om óf elektroniese, óf steriese verandering in die rodium(I) kern te bewerkstellig. Met hierdie doel is `n reeks rodium(I) komplekse voorberei en gekarakteriseer deur IR, UV/Sig en KMR spektroskopie. Enkelkristal X-straaldiffraksie is gebruik in die vaste toestand struktuurbepalings van hierdie komplekse wat beduidende veranderinge in die Rh···Rh afstand in elke rodium(I) kompleks getoon het. Dit het ook waardevolle inligting verskaf rakende hoe die molekules in hierdie een-dimensionele kettings gerangskik is. Rh···Rh afstande wat strek vanaf 3.134(3) Å tot 3.617(3) Å is gevind in die vaste toestand vir die reeks rodium(I) komplekse; die afstande stem ooreen met die UV/Sig absorpsieprofiel van elke kompleks. `n Voorlopige substitusiereaksie- en ewewigstudie is onderneem om die effek van veranderinge by die rodium(I) kern op die reaktiwiteit van die rodium(I) komplekse verder te evalueer. `n Belangrike ewewig neem deel aan die reaksie soos bewys deur die gebruik van 31P KMR en UV/Sig spektroskopie. In hierdie ondersoek is dit waargeneem dat deur tweedeorde tempokonstantes te gebruik om die reaktiwiteit van die komplekse te beskryf, die konstantes ooreengestem het met die pKa-waardes van die ongekoördineerde β-diketoonligande met `n toename in tempo van substitusie geassosieer met `n laer pKa van die vry ligand. 103Rh KMR chemiese verskuiwings van die rodium(I) komplekse het ook met die pKa-waardes van die vry ligande ooreengestem en het die elektroniese omgewing wat die metaalkern ervaar beklemtoon. Hierdie waarneming het `n effektiewe maatstaf verskaf vir hoe elektroniese veranderinge aan die rodium(I) kern die Rh···Rh interaksies van die vaste toestand strukture, asook die fisiese eienskappe van die verbindings, sal beïnvloed. Die studie is afgesluit deur `n vergelyking van al die parameters waardeur die rodium(I) komplekse geëvalueer was om vas te stel hoe veranderinge wat veroorsaak word deur verskillende koördinerende β-diketonato ligande te gebruik die een-dimensionele kettings wat via metalofiliese interaksies vorm, asook fisiese eienskappe soos die kleur wat deur die massa materiaal vertoon word, beïnvloed. Hierdie parameters het pKa, UV/Sig absorbansie-eienskappe, IR, 103Rh KMR, reaktiwiteit (k12 konstantes), Rh···Rh afstande en die torsiehoeke van die saamgestelde molekule ingesluit.af
dc.description.sponsorshipSASOLen_ZA
dc.description.sponsorshipUniversity of the Free Stateen_ZA
dc.description.sponsorshipNational Research Foundation (NRF)en_ZA
dc.language.isoenen_ZA
dc.publisherUniversity of the Free Stateen_ZA
dc.subjectRhodiumen_ZA
dc.subjectMetallophilic interactionsen_ZA
dc.subjectRhodium complexesen_ZA
dc.subjectNanowiresen_ZA
dc.subjectLigandsen_ZA
dc.subjectThesis (Ph.D. (Chemistry))--University of the Free State, 2015en_ZA
dc.titleStructural and reactivity study of rhodium(i) carbonyl complexes as model nano assembliesen_ZA
dc.typeThesisen_ZA
dc.rights.holderUniversity of the Free Stateen_ZA


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