This thesis presents advancements in the chemistry of selenium-bearing pincer ligands with respect to their synthesis, metal association and reactivity in addition to the overall nature of selenium as a donor atom. The synthesis of a new disilylamido ligand HN(SiMe2CH2SePh)2 2.1 and its potassium salt 2.2 is reported. The attempted metal association of these species was unsuccessful with various transition metals. Multinuclear NMR data suggests coordination to silver(I), 2.3 and copper(I), 2.4 with dπ-dπ back donation from the metal to the selenium donors. It is suggested from this data that –SePh can potentially act as a π-acceptor ligand as well as a σ- donor with heavy d metals. Another explanation for the observed shielding is conformational restrictions introduced by chelation. The preparation of new selenium-bearing diarylamine compounds RN(C7H6SeMe)2 (R=H: 3.1; R= Me: 3.10; R= Boc 3.11) via aryllithium chemistry is reported. Unsuccessful attempts to synthesize the –SePh and –SetBu derivatives are described using: aryllithium chemistry, Buchwald-Hartwig Amination cross coupling and Pd-catalyzed C-Se cross coupling. When reacted with MCl2(COD) (M= Pd, Pt), compound 3.10 coordinates with PdII forming a bidentate complex 3.12, while 3.1 forms tridentate complexes with PdII and PtII. NMR spectroscopy suggests the formation of a silver(I) complex 3.1-Ag from 3.1 and AgOTf, but X-ray diffraction data is required to determine its coordination motif. The new ligands and complexes have been fully characterized by (1H, 13C, 77Se) NMR spectroscopy and X-ray crystal structures are reported for 3.10, 3.12, 3.3 and 3.4. The NMR spectrum of 3.1-Ag exhibits a similar effect as the complexes of disilylamido ligands with suggested potential dπ-dπ back donation from the metal to the selenium donors. The catalytic ability of the new complex 3.3 has been tested in the Suzuki-Miyaura cross coupling reaction without notable improvements to existing catalysts. The instability of reactive intermediates may contribute to the low conversions or the size of the methyl group may decrease nanoparticle formation, a suggested active species. / October 2016

As propriedades de complexos de pentacianoferrato(II) e de pentaaminrutênio(II) contendo ligantes insaturados tais como dimetil sulfóxido, piridina, pirazina e derivados substituidos foram investigadas, em comparação com as de complexos análogos contendo ligantes saturados como a água, amônia e aminas alifáticas. Os complexos foram preparados tanto em estado sólido como em solução, tendo sido extensivamente caracterizados através de análises, medidas condutométricas e potenciométricas, espectros de absorção na região do visível, infravermelho e ultravioleta, espectros de ressonância nuclear magnética e através de estudos cinéticos e mecanísticos. Os complexos com ligantes insaturados mostraram-se termodinamicamente mais estáveis que os contendo ligantes saturados. Esse fato foi atribuido às interações de \"backdonation\" entre o metal e o ligante insaturado. As evidências que possibilitaram postular esse tipo de interação nos diversos complexos estudados, foram obtidas por meio de: a) análises de espectros d-d e de transferência de carga, b) medidas de força do oscilador, c) medidas das basicidades dos grupos cianetos coordenados, d) espectros de absorção no infravermelho, e) espectros de ressonância magnética protônica , f) medidas de potenciais de oxi-redução, g) comparações entre parâmetros cinéticos e termodinâmicos e h) medida da constante de equilíbrio para o processo de hidratação do ligante 4-formil piridina coordenado. A cinética de substituição nesses complexos conduziu a um mecanismo SN1 limite. Os resultados mostraram que as constantes de velocidade do processo de aquação são determinadas tanto pelas propriedades doadoras como pelas propriedades receptoras dos ligantes. Estudos de transferência de elétrons complexos pentaciano(piridina)ferrato(II) e (lII) apresentaram-se consistentes com um mecanismo tipicamente \"outer-sphere\" As. constantes de troca, K11, foram calculadas com o auxílio da teoria de Marcus e os resultados interpretados em termos de variações nos parâmetros de repulsão eletrostática dos reagentes / The properties of pentacyanoferrate(II) and pentaamineruthenium (II) complexes of unsaturated ligands such as dimethyl sulfoxide, pyridine, pyrazine and substituted derivatives were investigated in comparison to those of the analogous complexes of saturated ligans such as water, ammonia and aliphatic amines.These complexes were prepared both in solid state and in solution. They were extensively characterized by analysis, conductometric and potentiometric measurements, absorption spectra in the visible, infrared and ultraviolet region, nuclear magnetic resonance spectra and kinetics studies. The complexes of unsaturated ligands were shown to be thermodynamically more stable than those of saturated ligands. This fact was assigned to \"back-bonding\" interactions between the metal and the unsaturated ligand. The evidence that made it possible to postulate this kind of interaction in the several complexes studied in this thesis were obtained by: a) analysis of d-d and charge transfer spectra, b) oscillator strengths measurements, c) measurements of the basicities of coordinated cyano groups, d) infrared spectra, e) nuclear magnetic resonance spectra, f) redox potentials, g) comparison of kinetics and thermodynamic parameters and h) measurement of the equilibrium constant for the hydration process of coordinated 4-formyl pyridine ligand. The kinetics of substitution in these complexes indicated a limiting SN1 mechanism. The results show that the rate constants of the aquation process are determined equally by the donor and acceptor properties of the withdrawing ligand. Electron transfer studies in the pentacyano(pyridine)ferrate(II) and (III) complexes indicated a typical \"outer-sphere\" mechanism. The rate constants for the self exchange process, K11, were calculated according to Marcus theory and the results were interpreted in terms of variations in the electrostatic repulsion parameters of the reacting ions

Neste trabalho, descreve-se a síntese e caracterização de complexos binucleares derivados de [Ru(bpz)3]2+ e [Ru(bpy)2(bpz)]2+ (bpy = 2,2\'-bipiridina; bpz = 2,2\'-bipirazina) com os grupos [Fe(CN)5]3- e [Ru(bpy)2Cl]+. As propriedades espectroscópicas e eletroquímicas dos complexos resultantes [RuII(bpz)3RuII(bpy)2Cl]3+, [RuII(bpz)3FeII(CN)5]-, [RuII(bpy)2(bpz)RuII(bpy)2Cl]3+ e [RuII(bpy)2(bpz)FeII(CN)5]- foram investigadas, revelando transições de transferência de carga na faixa do UV-VIS e processos redox centrados no metal e nos ligantes. As espécies binucleares apresentaram tempos de vida na faixa de nanosegundos, não emitindo à temperatura ambiente. Experimentos de determinação da constante de velocidade de supressão (kq) por esfera externa e flash-photolysis indicaram a ocorrência do processo de supressão da emissão da unidade central pela periférica por um mecanismo de transferência eletrônica intramolecular. A separação de cargas foi explorada visando a construção de dispositivos do tipo diad e posteriormente para a elaboração dos triads, [FeIII(CN)5RuII(bpz)3RuII(bpy)2Cl]+ e [FeIII(CN)5Ru(bpy)2(bpz)RuII(bpy)2Cl]+. Estudos paralelos com o complexo [Ru(phen)2(bpz)Cl]+ (phen = 1,10-fenantrolina) também foram efetuados, visando caracterizar a coordenação monodentada do ligante bipirazina. Esse complexo não emite à temperatura ambiente, mas a 77 K exibe bandas de emissão em 628 nm e 680 nm e tempo de vida τr = 8,7 µs. O acoplamento aos grupos [Fe(CN)5]3- e [Ru(edta)H2O]2- levou à formação de complexos binucleares, os quais foram devidamente caracterizados. / The synthesis and characterization of bimetallic complexes such as [RuII(bpz)3RuII(bpy)2Cl]3+, [RuII(bpz)3FeII(CN)5]-, [RuII(bpy)2(bpz)RuII(bpy)2Cl]3+ and [RuII(bpy)2(bpz)FeII(CN)5]- (bpy = 2,2\'-bipyridine; bpz = 2,2\'-bipyrazine) were described and their spectroscopic and electrochemical properties investigated. The species showed characteristic charge transfer transitions in the UV-VIS region and redox processes centered on the metal and on the ligands. All of the species exhibited lifetime in the nanosecond range and are not emissive at room temperature. Determination of outer sphere quenching constants and flash-photolysis experiments demonstrated quenching of the emission of central group by an intramolecular electron transfer mechanism. Charge separation was pursued for the construction of dyads and lately triads, such as [FeIII(CN)5RuII(bpz)3RuII(bpy)2Cl]+ and [FeIII(CN)5Ru(bpy)2(bpz)RuII(bpy)2Cl]+. The complex [Ru(phen)2(bpz)Cl]+ (phen = 1,10-phenantroline) was studied in parallel, focusing on the unusual monodentate coordination of bipyrazine. This complex was not emissive at room temperature, but at 77 K it exhibited two emission bands, at 628 nm and 680 nm and lifetime τ = 8,7 µs. The attachment of groups such as [Fe(CN)5]3- e [Ru(edta)H2O]2- led to binuclear complexes that were consistently characterized.

As propriedades de complexos de pentacianoferrato(II) e de pentaaminrutênio(II) contendo ligantes insaturados tais como dimetil sulfóxido, piridina, pirazina e derivados substituidos foram investigadas, em comparação com as de complexos análogos contendo ligantes saturados como a água, amônia e aminas alifáticas. Os complexos foram preparados tanto em estado sólido como em solução, tendo sido extensivamente caracterizados através de análises, medidas condutométricas e potenciométricas, espectros de absorção na região do visível, infravermelho e ultravioleta, espectros de ressonância nuclear magnética e através de estudos cinéticos e mecanísticos. Os complexos com ligantes insaturados mostraram-se termodinamicamente mais estáveis que os contendo ligantes saturados. Esse fato foi atribuido às interações de \"backdonation\" entre o metal e o ligante insaturado. As evidências que possibilitaram postular esse tipo de interação nos diversos complexos estudados, foram obtidas por meio de: a) análises de espectros d-d e de transferência de carga, b) medidas de força do oscilador, c) medidas das basicidades dos grupos cianetos coordenados, d) espectros de absorção no infravermelho, e) espectros de ressonância magnética protônica , f) medidas de potenciais de oxi-redução, g) comparações entre parâmetros cinéticos e termodinâmicos e h) medida da constante de equilíbrio para o processo de hidratação do ligante 4-formil piridina coordenado. A cinética de substituição nesses complexos conduziu a um mecanismo SN1 limite. Os resultados mostraram que as constantes de velocidade do processo de aquação são determinadas tanto pelas propriedades doadoras como pelas propriedades receptoras dos ligantes. Estudos de transferência de elétrons complexos pentaciano(piridina)ferrato(II) e (lII) apresentaram-se consistentes com um mecanismo tipicamente \"outer-sphere\" As. constantes de troca, K11, foram calculadas com o auxílio da teoria de Marcus e os resultados interpretados em termos de variações nos parâmetros de repulsão eletrostática dos reagentes / The properties of pentacyanoferrate(II) and pentaamineruthenium (II) complexes of unsaturated ligands such as dimethyl sulfoxide, pyridine, pyrazine and substituted derivatives were investigated in comparison to those of the analogous complexes of saturated ligans such as water, ammonia and aliphatic amines.These complexes were prepared both in solid state and in solution. They were extensively characterized by analysis, conductometric and potentiometric measurements, absorption spectra in the visible, infrared and ultraviolet region, nuclear magnetic resonance spectra and kinetics studies. The complexes of unsaturated ligands were shown to be thermodynamically more stable than those of saturated ligands. This fact was assigned to \"back-bonding\" interactions between the metal and the unsaturated ligand. The evidence that made it possible to postulate this kind of interaction in the several complexes studied in this thesis were obtained by: a) analysis of d-d and charge transfer spectra, b) oscillator strengths measurements, c) measurements of the basicities of coordinated cyano groups, d) infrared spectra, e) nuclear magnetic resonance spectra, f) redox potentials, g) comparison of kinetics and thermodynamic parameters and h) measurement of the equilibrium constant for the hydration process of coordinated 4-formyl pyridine ligand. The kinetics of substitution in these complexes indicated a limiting SN1 mechanism. The results show that the rate constants of the aquation process are determined equally by the donor and acceptor properties of the withdrawing ligand. Electron transfer studies in the pentacyano(pyridine)ferrate(II) and (III) complexes indicated a typical \"outer-sphere\" mechanism. The rate constants for the self exchange process, K11, were calculated according to Marcus theory and the results were interpreted in terms of variations in the electrostatic repulsion parameters of the reacting ions

Après un chapitre d'introduction à la chimie des phosphamétallocènes, la seconde partie de la thèse apporte des améliorations aux protocoles développés dans notre équipe au cours des dernières années. Ceci a transformé une chimie autrefois " exotique " (car basée sur l'utilisation du ruthénium, métal coûteux) en une chimie plus pratique, basée sur des systèmes au fer. Le troisième chapitre fournit une exploration de la synthèse et du potentiel catalytique de phosphamétallocènes énantiopurs. Le quatrième chapitre fournit les clefs méthodologiques pour générer des phosphamétallocènes polysubstitués. Enfin, le cinquième chapitre de la thèse décrit un accès à la classe des macrocycles à seize chainons comprenant quatre dérivés phospholes, classe recherchée depuis longtemps. Le lien entre ces structures et les classes des porphyrines et calyxphyrines les rend particulièrement intéressantes.

This thesis addresses the potential for use of cobalt(III) complexes for functionalisation of lightly oxidised iron surfaces. In Chapter 2 the preparation of cobalt(III) complexes of a series of ligands based on 1,1,1-tris(aminomethyl)ethane is described. The synthesis was approached in two ways. Firstly, preparation of functionalised triol molecules as precursors to functionalised triamine ligands was investigated. This approach utilised the Tollens condensation of aldehydes with formaldehyde. In a second approach, the functionalisation of tetrakis(aminomethyl)methane in which one amine arm has been differentiated was used. The tetraamine was reacted with benzaldehyde and reduced with borohydride ion to give a secondary amine molecule that was then functionalised using alkyl or aryl sulfonyl chloride molecules. Chapter 3 describes the measurement of the binding of some cobalt(III) complexes to the surface of high surface area goethite. It was observed that complexes that have three exchangeable ligands bind more strongly than those with two exchangeable ligands. This is rationalised as being due to there being more bonds to the surface formed by complexes with three exchangeable ligands. It was also observed that complexes with three exchangeable ligands give greater surface coverage than those with two. This is likely due to the larger cross sectional area of the complexes with two exchangeable ligands in comparison to that of those with three, which blocks potential adjacent sites. Preliminary experiments on the use of the contact angle, SEM, EDS and QCM to characterise complex binding are explored in Chapter 4 . The results from the EDS and QCM experiments show that these may be valuable tools for measuring this binding and the subsequent surface properties, but have not yielded detailed results at this point. In Chapter 5 the use of cobalt(III) complexes as inhibitors of corrosion of iron in hydrochloric acid is investigated. All the complexes tested, even those that showed no binding to goethite surfaces, inhibit the corrosion to some degree. The level of inhibition is dependent on the complex, with [Co(tren)Cl2]Cl showing maximum inhibition of 81% and [Co(tame)Cl3] showing maximum inhibition of 53%. For some of the complexes, their concentration in solution over the course of the experiment was monitored by UV-vis. It was found that the complex disappears in a zero order reaction, the rate of which is dependent on the complex. However, the exact nature of this reaction is unknown. Furthermore, it was observed that inhibition of corrosion continues after the complex is no longer observed in solution. There is a difficulty in rationalising the inhibition being dependent on the complex identity, but not its continued presence in solution. Consequently, the mechanism of corrosion inhibition that explains all of these observations is still not known.

Ligand design plays an important role in the development and control of new coordination compounds. A new ligand architecture, Nindigo, has previously been reported and this study represents an expansion of that research to gain better insights into the attributes of this multifunctional ligand family. Mono- and bis-palladium chelates of Nindigo have been synthesized with resulting electrochemical measurements allowing for the reversible redox-active nature of the ligand set to be identified. The electronic absorption properties of these complexes were also studied. The presence of the palladium centre was found to drastically perturb the ligand centered π-π* transition resulting in significant red shifts in the absorption spectra with respect to free Nindigo. The main group coordination chemistry of Nindigo was explored by generating mono- and bis-BF2 Nindigo chelates. The electrochemical and spectral properties of these compounds were investigated with both families displaying weak emission in the NIR region. The bis-BF2 chelates were found to be sensitive in nature and decompose to the mono-BF2 chelates. In addition, heteroleptic complexes of mono-BF2 Nindigo chelates with palladium were also synthesized. The redox chemistry as well as the electronic absorption characteristics of these compounds provides a conceptual bridge between the two homologues. Homoleptic zinc and copper complexes of mono-BF2 Nindigo chelates have been synthesized. The zinc derivative serves as an “innocent” system where all redox and spectral properties are ligand centered and the oxidation states of both the metal and surrounding ligands can be assigned. The copper complexes exhibit more diverse chemistry with the redox and electronic absorption properties differing dramatically from the zinc system. A combination of EPR, XPS and computational analysis suggests the copper systems to be non-innocent in nature. In addition to the bis-bidentate anionic Nindigo ligand system, the fully oxidized neutral analogue has also been synthesized. DehydroNindigo exhibits significantly different chemical behaviour from Nindigo. Bridged ruthenium dimers have been synthesized that are obtained as two isomers, cis and trans (with respect to the bridging ligand). Both isomers exhibit rich electrochemical behaviour. The mixed valence states of both species are found, electrochemically, to be extremely stable with respect to disproportionation. / Graduate / 0485 / 0488 / gnawn@uvic.ca

The coordination chemistry of antimony(III) and antimony(V) have been investigated to reveal fundamental structural and electronic features. The limited scope of known cationic antimony(V) complexes was greatly expanded, including the first examples of pnictogen(V) trications. The systematic nature of these investigations led to the observation of redox chemistry, determined to be the result of reductive elimination of chlorobenzene and biphenyl from an antimony center. The reactivity of [Ph2Sb(OPyrMe)4][OTf]3 was investigated and it was found that the OPyrMe ligands are sufficiently labile to perform ligand substitution chemistry. However, when exposed to phosphines, ligand-centered reactivity prevails and phosphonium salts of the form [R3P(2-4-methylpyridine)][OTf] which may be useful reagents in the field of medicinal chemistry and drug design. While attempts were made to synthesise antimony(V) tetra- and penta- cations have been unsuccessful, the methodologies reported here will serve as a foundation to future endeavors. / Graduate / 2019-08-31

Knots are being discovered with increasing frequency in both biological and synthetic macromolecules and have been fundamental topological targets for chemical synthesis for the past two decades. However, only few synthetic molecular knots have been prepared to date and their properties remain largely unexplored. This thesis reports the synthesis of the most complex non-DNA molecular knot prepared to date: the self-assembly of five bis-aldehyde and five bis-amine building blocks around five metal cations and one chloride anion forms a 160-atom-loop molecular pentafoil knot (five crossing points). Chapter I aims to give the reader an overview of the current state of research in the field of template synthesis of molecular knots. Chapter II reports the synthesis and full characterisation of the most complex non-DNA molecular knot prepared to date, a pentafoil knot. Chapter III describes the synthesis of eleven pentameric cyclic double helicates derived from the scaffold of a pentafoil knot and presents an extensive study of the factors influencing the assembly process. Chapter IV reports the study of the self-sorting behaviour of a molecular Solomon link and a molecular pentafoil knot and their related non-interlocked systems. Chapter V the dynamic nature of pentameric circular helicates and a pentafoil knot is investigated, bringing insights on the subtle balance of thermodynamic and kinetic parametres involved in their self-assembly process. Chapter VI describes the halide binding properties of a synthetic molecular knot and doubly- and triply-entwined [2]catenanes based on circular Fe(II)-double-helicate scaffolds.

Single-Molecule Magnets (SMMs) are discrete molecules that exhibit slow relaxation of magnetization. Unlike conventional magnets that rely on the long range magnetic ordering in the form of domains, these molecules act as magnets independently, that is without the influence of neighbouring molecules. SMMs have intrigued physicists and chemists alike for over twenty years with their potential future applications in data storage quantum computing, and with this communal interest there has been significant collaboration between the two fields of research. SMMs have brought forth an opportunity for coordination chemists to muster their creativity and synthetic expertise in the rational design and development of these magnetic materials. From these new and fascinating compounds, both experimental and theoretical physicists have sought to develop and refine our understanding of the aspects of these molecular magnets in order to improve their performance at higher temperatures. In this work, new topologies for lanthanide complexes are explored using a novel Schiff base ligand. The magnetic properties of dinuclear, tetranuclear and octanuclear lanthanide complexes are discussed and correlated to their structural properties. The rational design of tetrazine-based Schiff base ligands for magnetic studies is also discussed in hopes of developing high performance SMMs.