FAculty of SCience School of Cheistry 9910913j messai@auvum.chem.wits.ac.za / The monodentate phosphine complexes bui3PMX (2a: M = Cu, X = Cl, 2b: M = Cu, X = I, 2c: M = Ag, X = Cl, 2d: M = Au, X = Cl) were synthesised in high yields from bui3P and MX. Their reaction with [Li{μ-N(R)C(but)C(H)R}]2 (R = SiMe3) gave the monomeric complexes bui3PCuN(R)C(but)=C(H)R (3a) and bui3PMC(H)RC(but)=NR (3b: M = Ag, 3c: M = Au) in moderate to high yields. The bonding mode in the 1-aza-allyl complexes 3a-c was found to depend strongly on the metal ion, with 3a being an enamide complex and 3b and 3c iminoalkyl complexes. The reaction of bidentate ligand dpmaaH2 (2,3-bis(diphenylphosphino)maleic acid) with R2Sn-precursors led to novel dialkyl tin dpmaa complexes (R2Sn)(O,O dpmaa) (6) (where 6a, R = Me; 6b, R = Bu) were synthesized. Complexation of the tin/phosphine complexes led to the heterobimetallic complexes {Au[(dpmaaO,O)(SnR2)]2}Cl (7a and 8a) {Au[(dpmaaO,O)(SnR2)][dpmaaH2]}Cl (7b and 8b) (where 7a and 8a, R = Me; 7b and 8b, R = Bu) and the mixed metal complexes {Au[(dpmaaO,O)(RuCl)]2}Cl (9a) {Au[(dpmaaO,O)(SnBu2)(dpmaaO,O)RuCl)]}Cl (9b) and {Au[(dpmaaO,O)(RuCl)][dpmaa]}Cl (9c). All compounds were fully characterised by multinuclear NMR spectroscopy and microanalysis (not 3a, 3b, 4 and 5) solid state IR spectroscopy (KBr-pellets) (4-9) and mass spectrometry (6-8). The solid state structures of complexes 2c, 2d, 3c, 6a and 6b (two polymorphs) have been determined by X-ray crystallography revealing the presence of rare trimeric macrocycles in the case of 6a and 6b. The anti-tumour activity of the metal complexes (6b and 7-9) was tested on a single cell-line (except 7a and 8a which were on eight cell-lines) and their activity was compared to cisplatin.

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Les carbènes N-hétérocycliques (NHC) sont très utilisés pour complexer les métaux de transition. Ils quittent rarement ce rôle de ligand ancillaire et trouvent, depuis une vingtaine d’années, des applications en catalyse ou, plus récemment, en chimie médicinale. Dans ce travail, nous discuterons d’une méthode de synthèse douce conduisant à la formation de complexes AgI – NHC via une source d’argent soluble. Cette méthode nous a permis d’obtenir des complexes bien connus mais également d’accéder à une nouvelle série de complexes NHC-Ag-phosphine. Nous présenterons également une nouvelle réaction où des NHC portant une fonction azoture à proximité du carbone du carbène quittent leur rôle de ligand ancillaire et conduisent à la formation d’hétérocycles azotés par cyclisation carbène-nitrène. Cette réaction sera présentée en détail, ainsi que la caractérisation spectroscopique concernant une sous-série de composés fluorescents obtenus par cette méthode. Enfin, nous présenterons une stratégie de post-fonctionnalisation de complexes développée dans notre équipe. Des complexes argent(I)-NHC portant un azoture proches du centre carbénique catalysent leur propre fonctionnalisation. De plus, des complexes de cuivre(I) portant des azotures en position éloignée du centre métallique seront greffés sur des nanoparticules magnétiques pour servir de catalyseur recyclables. / N-heterocyclic carbenes (NHC) are widely used to complex transition metals. They rarely leave their role as ancillary ligand and find, since 20 years, applications in catalysis or, more recently, in medicinal chemistry. In this work, we will discuss a mild synthetic method leading to the formation of AgI – NHC complexes via a soluble silver species. This method allowed us to obtain well known complexes but also to access a new series of NHC-Ag-phosphine complexes. We will also present a new reaction where NHC ligands bearing an azide function close to the carbenic center leave their role as ancillary ligand and lead to the formation of nitrogen rich heterocycles by a carbene-nitrene cyclization. This reaction will be presented in detail, along with the spectroscopic characterization regarding a sub-series of fluorescent compounds obtained by this method. Finally, we will present a post-functionalization strategy of complexes developed in our team. Silver(I)-NHC complexes tagged by an azide close to the carbenic center catalysed their own functionalization. Moreover, copper(I) complexes tagged by an azide function in a distant position from the metallic centre will be grafted on magnetic nanoparticles to act as recyclable catalysts.

Computational chemistry has gained interest as a characterization tool to predict photoluminescence, reactivity and structural properties of organic and transition metal complexes. With the rise of methods including relativity, these studies have been expanded to the accurate modeling of luminescence spectra of complexes with considerable spin-orbit splitting due to heavy metal centers as well as the reaction pathways for these complexes to produce natural products such as hydrogen gas. These advances have led to the synthesis and utility of more effective catalysis as well as the development of more effective organic light emitting diodes (OLEDs) through the incorporation of organometallic complexes as emitters instead of typical organic emitters. In terms of significant scientific advancement presented in this work is in relation to the discovery of significant spin-orbit splitting in a gold(I) alkylphosphine complex, where the splitting results in the states that emit in different colors of the visible region of the electromagnetic spectrum. This work also reveals the discovery both computationally and experimentally, of a genuine polar-covalent bond between two-closed shell metals. This work highlights a complex with an incredibly short gold(I) – copper(I) intermetallic distance leading to a vibrational frequency and dissociation energy that is on par with those of other systems with single-bonded metal centers. Lastly, this work outlines a strategy for the production of hydrogen gas through the use of trinuclear cyclic coinage metal complexes as catalysis to split hydrohalic acids.