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Various chelating ligands have been designed and synthesised; these include amino-amide ligands, tetraacetic acid systems and sulfur-containing amide ligands. Difficulties in the synthesis and purification of the amino-amide ligands were largely overcome, permitting the mono acylation of ethylenediamine and the synthesis of bis(2-aminoethyl)-2-benzylpropanediamide. Novel tetraacetic acid ligands, based on the propanediamide backbone and targeted as EDTA analogues, were obtained from their methyl and benzyl esters; but the instability of the tetraacids prevented their full characterisation. Bidentate, tridentate and tetradentate sulfur-containing monoamide ligands, based on the ortho-thio acetanilide moiety, were designed to specifically chelate platinum and palladium in the presence of base metals. In their synthesis, thiocyanation was used to introduce the orth-thio group on para-substituted anilines, and further functionalisation was achieved via appropriate protection of nucleophilic sulfur moieties. A range of tetradentate, sulfur-containing diamide ligands was also synthesised by reacting substituted 2-mercaptoacetanilides with 1,2- dibromoethane. Novel ligands were characterised by spectroscopic (¹H and ¹³C NMR; IR and M S) techniques and elemental (combustion and high resolution MS) analysis. Computer modelling and ¹H NMR chemical shift data have been used to explore the conformational preferences of the sulfur-containing acetanilide ligands. The macrocyclic ligands and systems with ortho-methylthio substituents appear to exhibit the greatest degree of coplanarity of the aromatic and amide functions. Solvent extraction studies revealed that the sulfur-containing amide ligands selectively extracted palladium(II) from platinum(II), copper(II}, nickel(II} and cobalt(II}. Even though the palladium(II} was extracted from an acidic medium, certain monoamide ligands were able to complex palladium(II) through their sulfur and deprotonated amide nitrogen donors, a trithia monoamide ligand being observed to displace all the chloride ligands on palladium to form a monomeric tetracoordinate complex. The diamide ligands, however, appeared to favour extraction of palladium(II) by coordination through their sulfur donors, forming 5-membered sulfur-sulfur chelates. In basic media (pH 8-9), selected sulfur-containing monoamide and diamide ligands have been shown to complex platinum(II) and palladium(II) through their sulfur and deprotonated amide nitrogen donors. At neutral pH, a dimercapto monoamide ligand has been shown to complex platinum from cisplatin with partial expulsion of the ammine ligands, while a macrocyclic trithia monoamide ligand has been observed to complex platinum from tetrachloroplatinate with concomitant deprotonation of the amide nitrogen. Where possible, the complexes were characterised by infrared and ¹H NMR spectroscopy and have also been studied using the computer modelling soft-ware programmes, Momec® and Hyperchem®.

Apart from their general usage as tanning agents for hides and skins, the natural tannins have been used since earliest times for various other purposes. The blue-black iron tannate complex was used by ancient Egyptians as a hairdye and for many conturies this complex was the main source of writing inks. Wattle tannin is known to form complexes with many metal ions. The chief use of tannin complexes has been in gravimetric analyses, since aqueous solutions of tannins readily precipitate metal ions under certain experimentel conditions. At the present time the nature of the precipitated complexes has not been investigated however, because in the gravimetric method the complexes are ignited and the metal determined as its oxide; hence no knowledge of the complexes themselves was required.

The study involves the synthesis and structural characterization of manganese carbene complexes. The synthesis of dimanganese monocarbene complexes [Mn2(CO)9{C(OEt)(heteroaryl)}] was done via the classical Fischer method, and a range of complexes containing heteroaromatic substituents, e.g. 2,2'-bithiophene, thiophene, furan and N-methyl pyrrole, was isolated. These complexes displayed a novel configuration with the carbene ligand in the axial position, in contrast to the equatorial position found for the analogous rhenium compound and other dimanganese complexes known from the literature. The possibility of manipulating the position of the carbene ligand in the binuclear complexes was investigated by a nucleophilic substitution of the ethoxy substituent with an amine substituent. Only aminolysis with small, primary amines such as ammonia and propylamine, proved successful. The propylaminocarbene ligands retained their axial configuration, but a conversion to the more thermodynamically stable equatorially substituted carbene ligands was observed for the complexes [Mn2(CO)9{C(NH2)(heteroaryl)}], while mixtures of the equatorial and axial isomers were observed in solution. Structural X-ray analysis proved that although the equatorial position is more electronically favourable, steric hindrance by the second manganese pentacarbonyl moiety prevented ethoxy- and propylamino-substituted carbene ligands to adopt this configuration. A kinetic study of the aminolysis reaction was done in an effort to elucidate the reaction mechanism and to explain the axial-equatorial conversion. Due to the competing decomposition reaction of the product and reagent complexes with that of the substitution reaction, no information about reaction intermediates could be obtained. The target mononuclear complexes [Mn(CO)4{C(OEt)(heteroaryl)}X] (X = Br, I) was obtained by cleavage of the metal-metal bond of the binuclear precursor complexes. Cleaving of the Mn-Mn bond was done oxidatively by halogens, without affecting the carbene ligand. The product complexes have an assembly resembling that of the Grubbs ruthenium metathesis catalyst. Interestingly, the cleaved complexes were found to have a cis configuration of the carbene and halide ligand. Copyright 2006, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Bezuidenhout, DI 2006, Synthesis and Structural Investigations of manganese carbene complexes, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-02122007-120832 / > / Dissertation (MSc)--University of Pretoria, 2007. / Chemistry / unrestricted

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Le comportement des polymères amorphes suscite un intérêt certain dans le monde de la recherche car leurs domaines d'application sont très varies. La transparence et une grande rigidité sont de grands atouts qui font du polycarbonate (pc) un des polymères techniques les plus usités. Les lois phénoménologiques ne permettent pas de reproduire correctement le comportement de ce polymère. Cette étude se propose donc d'étudier le comportement du pc a partir d'essais simples et complexes de compression uniaxiale en quasi statique et à température ambiante. Des essais comprenant plusieurs cycles de charge – décharge – maintien a effort constant sont réalisés avec différents niveaux et temps de maintien. Une autre série d’essais est destinée a mettre en évidence l’anisotropie induite du pc. L’ensemble de ces essais est ensuite comparé au modèle de boyce, parks et argon (1988) très référencé dans la littérature afin de tester sa validité. Certaines lacunes de cette approche sont ainsi mises en évidence. Finalement, un nouveau modèle micromécanique est proposé, basé sur la structure du polymère et l'évolution de celle-ci et inspire des modèles de plasticité pour les métaux. La notion de pelote comprenant plusieurs chaînes moléculaires est introduite. La déformation totale est décomposée de façon additionnelle en parties élastique, anélastique et plastique. L’écrouissage est naturellement introduit grâce à la combinaison de la notion de pelote et du modèle de lin (1957). Une première validation de ce modèle est proposée, fournissant des résultats particulièrement encourageants pour les travaux futurs / The behaviour of amorphous polymers is of a great interest in the research world because their application fields are various.transparency and high stiffness are the major advantages which made polycarbonate (pc) one of the most machined technical polymers. Phenomenological laws don’t allow reproducing correctly the behaviour of this polymer. this study proposes to analyze the pc’s behaviour based on simple and complex uniaxial compressive tests, in quasi static conditions and at room temperature. Tests with different loading – unloading – maintaining at constant forces cycles are done with various levels and maintaining times. Another series of tests is dedicated to show the induced anisotropy of pcs. all these experiments are compared to the boyce, parks and argon’s model (1988) very represented in the literature in order to check its validity. some lacks of this approach are enlightened. finally, a new micromechanical model is proposed based on the polymer structure and on its evolution, and inspired from metal plasticity models. the concept of balls which include several molecular chains is introduced. the total strain is additionally decomposed of three parts: elasticity, anelasticity and plasticity. The hardening is naturally introduced thanks to the combination of ball concept and lin’s model (1957). A first validation of this model is proposed, giving encouraging results for further works

A series of chelating amino siloxide and alkoxide ligands have been prepared. Barium, lanthanide and zirconium complexes bearing these new ligands have been synthesized and characterized by NMR or X-ray crystallography. Reactivity of the zirconium complexes has been studied. The tris(siloxide) lanthanide(III) complexes are all monomeric in both solution and solid-state. A yttrium tris(siloxide) and a zwitterionic ytterbium tetrakis(siloxide) complexes have been characterized by X-ray crystallography. The yttrium complexes have shown high volatility. Mono(siloxide) barium(II) silamide complexes are dimeric as determined by X-ray crystallography, and barium bis(siloxide) exists as a monomer-dimer equilibrium in hydrocarbon solvents. Although highly soluble in hydrocarbon solvents, the barium complexes are non-volatile. A new aryl(siloxide) ligand has been synthesized and used as an ancillary ligand for the preparation of lanthanide dialkyl complexes. Although ligand redistribution was not observed, “ate”-complexes were isolated instead of neutral dialkyl complexes. Zirconium bis(aminodiolate) complexes were synthesized by reaction of tetrabenzyl zirconium and two equivalents of the ligands. The substituents on nitrogen were found to have a great effect on the structure. Mono(aminodiolate) zirconium dialkyl complexes were successfully synthesized by three different methods: protonolysis, ligand redistribution and metathesis. Thermal decomposition of these zirconium dialkyl complexes was found to show a marked dependence on the substituents at nitrogen. The α-methyl benzyl derivative decomposed by ortho-metallation of phenyl group exclusively and resulted in clean formation of a metallacyclic complex. The reaction of primary amines with the metallacycle allowed isolation of amide intermediates protonolysis of the benzyl group, and eventually resulted in formation of bridging imide complexes. The insertion reaction of carbonyl groups (C=O) into the metallacycle Zr-carbon bond proceeds regio- and stereoselectively. The first insertion products of carbonyl insertion were isolated, and the β-naphthaldehyde insertion product was characterized by X-ray crystallography. The metallacycle exhibited catalytic activity towards alkyne cyclotrimerization without preactivation. Zirconium cationic complexes were generated by alkyl abstraction using [special characters omitted]. The cationic complexes generated from the zirconium dibenzyl derivatives showed catalytic activity towards both ethylene and 1-hexene polymerization. A new cyclopentadienyl ligand bearing pendant fluorinated alkoxide functionality was synthesized. The zirconium complexes bearing this ligand exhibited remarkably high Lewis acidity, and the dichloride complex was shown to be catalytically active towards vinylether polymerization. / Graduate

At the beginning, a brief overview of two-dimensional materials as well as an introduction of the organic metal complex nanosheets was presented in chapter 1. In this section, the attention was mainly focused on the concept of the 2D nanomaterial, including the design strategies, the categories, the synthetic approaches and the characterization methods. Also, the materials used as electrodes of batteries for energy storage were generally introduced. Those electroactive materials were classified according to their different functional mechanism. The opportunity and challenge of this kind of electroactive materials were then demonstrated. At last, the current development of the 2D materials as electrodes, including the typical structures and the superiority, was indicated.;A brand-new symmetric four-way terpyridine derivative (1,2,4,5-tetrakis(4-(2,2':6',2"-terpyridyl)phenyl)benzene) (L7) was then designed and coordinated with Co(II) ion to assemble a novel bottom-up multilayer nanosheet 7-Co in chapter 4. The generated nanosheet featured moderate mechanical strength and insolubility in both aqueous solution and organic solvent, which can facilitate the purification and collection of the product. By taking the advantages of the reversible and robust redox activity of Co2+/Co3+, a dual-ion battery cathode was achieved by employing the 7-Co and thus it reveals the possibility of this kind of metal organic complex nanosheet to be utilized in a battery.;1.7\xFinally, the findings, analysis results and future work were concluded in chapter 6. And the experimental details were described in chapter 7