This thesis is concerned with the asymmetric synthesis of cyclopropyl derivatives via the use of chiral iron acyl complexes of the type (η⁵-C₅H₅)Fe(CO)(PPh₃)(COCH=CR'R), Chapter 1 reviews previous routes to optically active cyclopropyl derivatives and reviews the use of the chiral auxiliary (η⁵-C₅H₅)Fe(CO)(PPh₃) for asymmetric synthesis. Chapter 2 describes the synthesis of the complexes (η⁵-C₅H₅)Fe(CO)(PPh₃)(COCH=CRR') and presents a conformational analysis of the α, β-unsaturated acyl ligand. Chapter 3 describes the diastereoselective synthesis of cis- substituted cyclopropyl complexes via the reaction of Z-α, β-unsaturated iron acyl complexes with electrophilic alkylidene species. Decomplexation, to give the corresponding cyclopropyl esters, occurred without epimerisation of the cyclopropane ring. By the use of homochiral iron acyl complexes the enantioselective synthesis of cyclopropyl derivatives was achieved. Section A describes methylene addition and Section B isopropylidene addition reactions. Section C describes attempts to synthesise pyrethroid insecticide precursors which occurred with good diastereoselectivity but poor regioselectivity. Section D describes electrophilic ethylidene addition reactions in which the chiral auxiliary exerts good stereochemical control over three new chiral centres. Chapter 4 describes the diastereoselective synthesis of trans- substituted cyclopropyl complexes via the reaction of E-α, β-unsaturated iron acyl complexes with nucleophilic alkylidene transfer reagents. Section A describes methylene transfer reagents. Whilst α-lithiosulphides and α-lithiosulphoxides were of limited use, iodomethyllithium (generated in situ) resulted in highly diastereoselective syntheses of the cyclopropyl complexes. Decomplexation, to give the corresponding cyclopropyl esters, occurred without epimerisation of the cyclopropane ring. By the use of homochiral iron acyl complexes the enantioselective synthesis of cyclopropyl derivatives was achieved. Section B describes the generation of 1-iodoethyllithium and 1-iodobutyllithium and their reactions as nucleophilic alkylidene transfer reagents. The stereo- chemistry at two of the new chiral centres is controlled by the iron chiral auxiliary, whilst that at a third is controlled by a number of factors.

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Magister Scientiae - MSc / G1 and G2 dendrimeric salicylaldimine ligands containing both substituted and unsubstituted aryl rings were synthesized via a Schiff base condensation of the appropriate salicylaldehyde and the peripheral amino groups of the corresponding G1 and G2 polypropyleneimine dendrimers. The new ligands were characterized using FTIR, 1H NMR and 13C NMR spectroscopy, elemental analysis and ESI mass spectrometry. The dendrimeric ligands were converted to multinuclear nickel complexes by reaction with nickelacetate. The metal complexes were characterized by FTIR spectroscopy, elemental analysis and ESI mass spectrometry.Some of the dendritic complexes were evaluated as catalyst precursors in the oligomerization of α-olefins such as ethylene and 1-pentene, using aluminium alkyls such as EtAlCl2 and modified methylaluminoxane (MMAO) as activators. All the dendrimeric catalysts evaluated are active in the oligomerization reactions. From the oligomerization results it was observed that there is a clear dendritic effect, in that both catalyst activity as well as selectivity are impacted by the dendrimer generation. In most cases it was observed that the second generation complexes show higher activity than the corresponding first generation complexes.The dendrimeric complexes were also evaluated as catalyst precursors in the vinyl polymerization of norbornene. In this case methylaluminoxane (MAO) were employed as an activator. Once again it was noted that a dendritic effect is operative, with second generation metallodendrimers having a higher activity than the first generation complexes. / South Africa

The chemistry of co-ordination compounds in general has played an important role in the development of the modern theory of valency, but the properties of complex salts between chromium and organic compounds containing carboxyl and amino- groups are of additional interest because of their bearing on the theory of certain technological processes such as chromium plating and, in particular, chrome-tanning. Owing to the rapid development of valence theory over the last two decades the technological chemist finds himself at a disadvantage vis-a-vis his academic counterpart in attempting to interpret the results of researches relating to these compounds as he must rely on the less powerful "classical" approach to his problems. Hence the need was felt for a brief survey of modern concepts of valency in terms of wave mechanics. For a more extended study the reader may consult the appropriate references and text books.

In this work physical and analytical methods have been used to investigate the potassium salts of certain dioxalato chromium (III) complexes. The solid potassium salts of the trioxalatochromiate and the cis and trans dioxalatodiaquochromiates together with a salt corresponding to potassium dioxalatosulphatoaquochromiate were prepared. The mono- and dihydroxo derivatives of the cis and trans dioxalatochromiates were also obtained in aqueous solution. The methods of preparation and analysis used are described. Spectrophotometric absorption curves obtained on solutions of these salts using a Beckman Spectrophotometer are in agreement with results of previous workers, and the new absorption curve obtained from a solution of the solid cis dioxalatodiaquochromia salt shows that it is pure and gives additional proof of the completeness of the trans - cis isomerisation. Summary, p. i.

(1) The ammonium, potassium and sodium salts of three complex thorium oxalates were prepared and studied. (2) Their solubilities and conditions of stability were studied. (3) The reaction between thorium and excess oxalate, and vice versa, was studied by means of conductivity and high frequency conductivity measurements. (4) The formation constant of Th(C₂O₄)₄⁴⁻ and Th(C₂O₄)₃²⁻, and the solubility product of (NH₄)₂Th₂(C₂O₄)₅, were determined by a solubility method.

This study investigates the synthesis of rhenium(III)-isocyanide complexes with potentially bidentate ligands, as well as the reactivity of isocyanide ligands toward rhenium(I) and (V). The crystal structures of all the complexes have been determined by X-ray diffraction methods. The coordination behaviour of trans-[ReIIICl3(t-BuNC)(PPh3)2] with aniline and its derivatives were investigated. The isocyanide-containing rhenium(V) complexes [ReCl3(t-BuNC)(L)(PPh3)] were isolated, with the ligands H2L (aniline, o-phenylenediamine and anthranilic acid). In all these complexes the dianionic ligands L are coordinated monodentately as the imide. However, with 2-aminophenol the complexes [ReVCl2(t-BuNC)(L)(PPh3)2](ReO4) and [ReIIICl2(t-BuNC)(ibq)(PPh3)2] (ibq- = 2-iminobenzoquinonate) were identified as the products. [ReCl2(t-BuNC)(L)(PPh3)2](ReO4) is the product of a disproportionation reaction from Re(III) to Re(VII) and Re(V). All the above complexes show a distorted octahedral geometry around the rhenium. The products of the reaction of the Re(I) complex [Re(CO)5Cl] with isocyanides (tert-butyl- and cyclohexylisocyanide) are reported. Rhenium(I) tricarbonyl complexes of the form [Re(CO)3(CNR)2Cl] were isolated and they were characterized structurally and spectroscopically. The tricarbonyls are coordinated in the typical facial-fashion, whereas the isocyanides are coordinated cis to each other. The reaction of [Re(CO)3(t-BuNC)2Cl] with H2O led to the formation of the rhenium(I) complex [Re(CO)3(t-BuNC)2(OH2)] in which the aquo ligand can readily be substituted by a more complex ligand. The reaction of the rhenium(V) complexes cis-[ReO2I(PPh3)2] and mer-[ReOCl3(SMe2)(OPPh3)] with isocyanides were studied. The seven-coordinate trigonal prismatic, square faced monocapped rhenium(III) complex [ReI3(t-BuNC)3(PPh3)] was surprisingly isolated upon reacting cis-[ReO2I(PPh3)2] with tert-butyl isocyanide. The dimeric complex (μ-O)[ReOCl2(CNC6H11)2]2 was obtained from the reaction of mer-[ReOCl3(SMe2)(OPPh3)] with cyclohexyl isocyanide.

The present thesis is based on a paper by Bencivenga. In this paper the author develops a theory of function for the dual and bireal variables. He constructs the "retto" and "hyperbolic" planes for the geometric representation of the dual and bireal variables, respectively, and establishes a type of conformal mapping of these planes into themselves by means of differentiable functions of the variable. Further, in each of these planes he proves the analogue for the Cauchy integral theorem of the complex plane. Finally he shows that functions of the dual and bireal variable which possess all derivatives at a given point of the plane may be expanded in a Taylor series about that point. In the first chapter we give a summary of this paper. Bencivenga’s dual and bireal number systems, and also the complex number system, are two-dimensional cases of the ɳ - dimensional associative, commutative linear algebra with unit element. In chapter II we generalize Bencivenga's function theory to functions over the above mentioned linear. An important class of results from the theory of functions of a complex variable are not generalizable, since they depend on the field properties peculiar to the complex algebra. In chapter III we undertake a detailed study of the hyperbolic plane with particular reference to the conformal properties of differentiable functions of the bireal variable, as a special case of conformal transformation of the hyperbolic plane, we study the bilinear transformation. We find that the rectangular hyperbola is the geometrical form which is invariant under this transformation of the hyperbolic plane. Singularities play a larger role in this theory than in the case of the analgous transformation theory of the complex plane. / Science, Faculty of / Mathematics, Department of / Graduate

Motifs are over-represented subgraphs in a complex network, and represent the building blocks of the network. There is a lack of studies that apply complex network theory in a supply chain context. In this dissertation 3-node motifs were identified and analysed in a complex network representing direct freight trips between firms in the Nelson Mandela Bay Metropolitan, South Africa. The G-Tries and ISMAGS algorithms were tested on small complex networks, and were compared according to quantitative and qualitative properties. It was found that ISMAGS is the most suitable for this dissertation. Freight activities were identified from raw GPS traces of freight vehicles, and the activities were clustered into firms using a density-based clustering algorithm. Multi-objective optimisation indicated that the clustering parameter configuration γ = (20, 20) can be used to increase the visual accuracy of the firms, while maximising the completeness of the complex network. The freight complex network was built by identifying direct trips between firms. Using ISMAGS, it was found that three firms with two (X0X) or three (XXX) reciprocal freight trips between them are statistically overrepresented in the network. A brewery, shopping centres, distribution centres, and truck stops frequently appeared in the motifs. Motifs that contain the brewery and one of the truck stops were identified as the most central motifs based on the number of direct freight trips that occur in the motifs. Some freight trips in XXX motifs occur frequently over long distances, increasing total transport costs of the firms. Supply chain improvements can be applied to these identified firms. It was also found that there is a relationship between ranking firms according to the number of motifs they appear in and their degree centrality scores. This relationship can be studied more rigorously in future work. Another avenue for future research is to study the supply chain structures of firms in motifs, as well as the commodity flows between firms in motifs. / Dissertation (MEng)--University of Pretoria, 2016. / Industrial and Systems Engineering / Unrestricted

La plupart des voies de signalisation qui régule la croissance cellulaire et le métabolisme sont sous le contrôle du mécanisme du complexe I de la rapamycine (mTORC1). L'un des régulateurs en amont de mTORC1, impliqués dans la détection des acides aminés et l'autophagie, est complexe SEA, chez la levure, et le complexe GATOR, chez les mammifères. Plusieurs composants de GATOR sont dérégulés dans de nombreux cancers et maladies neurodégénératives. Malgré l'intérêt scientifique vis à vis du complexe SEA / GATOR, de nombreux détails concernant sa fonction et son implication dans différents troubles humains sont encore inconnus et restent à investiguer.L'objectif principal de ma thèse était d’élargir notre connaissance sur le complexe SEA / GATOR, et plus particulièrement en ce qui concerne son rôle dans la modulation des voies de signalisation cellulaire. Étant donné que le SEA / GATOR est très conservé, j'ai effectué les expériences en utilisant deux modèles cellulaires : levure S. cerevisiae et lignées cellulaires humaines. Les résultats obtenus ont permis de démontrer un nouveau rôle pour le NPRL2, composant de GATOR, distinct de sa fonction dans la régulation de la voie mTORC1. Nous avons constaté que l'expression ectopique de la NPRL2 induit un stress oxydant et conduit aux dommages de l'ADN et à l'apoptose. Les études sur la levure ont révélé que le complexe SEA relie la voie mTORC1 et la régulation du contrôle de la qualité des mitochondries. Par conséquent, le complexe SEA / GATOR émerge en tant que régulateur multifonctionnel de plusieurs processus cellulaires. / The major signaling pathway that regulates cell growth and metabolism is under the control of the mechanistic target of rapamycin complex 1 (mTORC1). One of the mTORC1 upstream regulators involved in amino acid sensing and autophagy is called the SEA complex in yeast and GATOR in mammalian cells. Several GATOR components are deregulated in many cancers and neurodegenerative diseases. Despite of the growing interest to the SEA/GATOR, many details concerning its function and implication in different human disorders are still unknown.The main objective of my thesis was to extend our knowledge about the SEA/GATOR, especially what concerns its role in the modulating cellular signaling network. Because the SEA/GATOR is highly conserved I performed the experiments using two model systems - budding yeast S. cerevisiae and human cells lines. The results I obtained allowed to demonstrate a new role for the GATOR component NPRL2, distinct from its function in mTORC1 regulation. We found that ectopic expression of NPRL2 induces oxidative stress and leads to the DNA damage and apoptosis. The studies in yeast revealed that the SEA complex connects the TORC1 pathway and the regulation of mitochondria quality control. Therefore, the SEA/GATOR complex is emerging as a multifunctional regulator of several cellular processes.