Dissertations / Theses on the topic 'Transition metal complexes'
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1
Barron, Andrew Ross. "Transition metal aluminohydride complexes." Thesis, Imperial College London, 1986. http://hdl.handle.net/10044/1/37935.
2
Jasim, Naseralla. "Transition metal bifluoride complexes." Thesis, University of York, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323538.
3
Veighy, Clifford Robert. "Novel cyclopentadienyl transition metal complexes." Thesis, University of Southampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327366.
4
Zard, P. W. "Transition metal complexes with pyrimidinethiones." Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/47322.
5
Johnson, Donald Martin. "Cyanoscorpionates and Transition Metal Complexes." Digital Commons @ East Tennessee State University, 2010. https://dc.etsu.edu/etd/1725.
Abstract:
The new dihydrobis(4-cyano-3-tert-butylpyrazolylborate) ligand has been synthesized. Isolated crystals of the thallium complex were collected and structurally characterized by X-ray diffraction. Transition metal complexes of the ligand are currently under investigation.
6
Holder, Alan John. "Studies on transition metal macrocyclic complexes." Thesis, University of Edinburgh, 1987. http://hdl.handle.net/1842/10961.
7
Cheung, Wai Man. "Transition metal complexes with dichalcogenoimidodiphosphinate ligands /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202007%20CHEUNG.
8
Redfern, C. M. "Electronic structure of transition metal complexes." Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235094.
9
Mobbs, B. E. "Arene transition metal complexes in synthesis." Thesis, University of Oxford, 1985. http://ora.ox.ac.uk/objects/uuid:4c7030d4-297e-4af8-a622-d5b4963fc0a3.
Abstract:
This thesis deals with the applications of organopalladium and organochromium chemistry to the functionalisation of the benzopyran ring system, at a variety of oxidation levels. Section I demonstrates the functionalisation of 3-, 6-, and 8-bromochromones via palladium (0) insertion into the C-Br bond. The resultant arylpalladium species are shown to undergo addition to the least substituted end of a variety of olefins including methyl acrylate, acrylonitrile and styrene. Subsequent palladium-hydride elimination leads to overall palladium catalysed vinylation of the chromone and the synthesis of a number of novel compounds. Vinylation occurs regiospecifically at the site of chromone bromination and is shown to allow clean substituent introduction into each of the three sites. The palladium catalysed reaction of 3,6-dibromo-chromone with methyl acrylate leads to vinylation at both the C3 and C6 positions. Carbonylation of the 6-bromochromone in ethanol or butanol leads to the 6-ethyl or 6-butyl esters respectively. The palladium catalysed vinylation of the 6-bromochromone with ethyl vinyl ether leads to a mixture of products from addition of the chromone to either end of the olefin. With p-bromophenol or p-bromo-N,N-dimethylaniline the reaction gives exclusively the acetylated product arising from addition to the more substituted end of the olefin. This change in orientation is rationalised by considering the polarisation of the olefin and the arylpalladium species. Section II demonstrates the functionalisation of chroman and 4-chromanol via coordination to the Cr(CO)3 moiety. (η6-Chroman)Cr(CO)3 is synthesised and is shown to undergo regiospecific ring deprotonation at C8 under kinetic conditions or regiospecific benzylic deprotonation at C4 under thermodynamic conditions. The resultant anions are quenched with alkyl halides, aldehydes, Eschenmoser's salt and methyl disulphide resulting in selective functionalisation of either site. No mixed products are observed. The uncomplexed arene is shown to be totally unreactive under identical conditions. (η6-4-Chromanol)Cr(CO)3 is synthesised and is shown to undergo regiospecific C8 ring deprotonation by comparison with authentic samples of the C5 and C8 methylated alcohols. Protection of the hydroxyl group as its methyl, t-butyldimethylsilyl or methoxymethyl ethers is found not to alter the regiochemistry of deprotonation. The 4-chromanol t-butyldimethylsilyl and tri-i-propylsilyl ethers are synthesised and coordinated to the metal unit. Cleavage of the silyl ethers is shown to proceed with loss of stereochemistry, indicating C-0 bond cleavage.
10
Bridgewater, Brian Michael. "Sterically hindered chiral transition metal complexes." Thesis, Durham University, 1998. http://etheses.dur.ac.uk/5022/.
Abstract:
This thesis describes the synthesis, characterization and study of a series of organometallic compounds which all contain the same new ligand, l-phenyl-3-methyl-4,5,6,7-tetrahydroindenyl. The ligand forms a chiral complex once coordinated, and is relatively bulky when compared with ligands such as cyclopentadienyl or 4,5,6,7-tetrahydroindenyl.Chapter one of this thesis introduces cyclopentadienyl ligand chirality, cyclopentadienyl metal complex chirality and sterically demanding cyclopentadienyl systems. The synthesis and chemistry of tetrahydroindenes and some applications of chiral cyclopentadienyl metal complexes and their bulky analogues are also reviewed. Chapter two describes modifications to a literature preparation of the tetrahydroindenone precursor of the new tetrahydroindenyl ligand which lead to higher yields. The synthesis of the ligand itself is described, as well as the synthesis of a benzylidene-substituted hexahydroindene, which demonstrates a limitation in the flexibility of the synthetic route chosen. The synthesis, characterization and various properties of the following iron(II) compounds are discussed in chapter two; bis-l-phenyl-3-methyl- 4,5,6,7-tetrahydroindenyl iron (II), 2.3, l-phenyl-3-methyl-4,5,6,7-tetrahydroindenyl iron(II) dicarbonyl dimer, 2.4, and l-phenyl-3-methyl-4,5,6,7-tetrahydroindaiyl methyl dicarbonyl iron(II), 2.5. For all these iron complexes, the solid state molecular structures and the absolute configuration of the chiral ligand were determined using single crystal X-ray d iffraction. For 23 and 2.4, three isomers are possible, two enantiomers that are collectively termed the rac-isomer and a third isomer, the meso- isomer. Cyclic voltammetric studies on 2.3 indicate that it has a reversible one electron oxidation at 0.187 V (with respect to a non-aqueous Ag/AgCl standard electrode). The difference between this and the reversible one electron oxidation for (η-C(_5)H(_5))(_2)Fe (with respect to the same standard) is -0.314 V, therefore 2.3 is shown to be much more easily oxidized than (η-C(_5)H(_5))(_2)Fe. The solution-state infi-a-red spectrum of 2.4 is explained, with reference to a literature analysis of the unsubstituted analogue [CpFe(CO)(_2)](_2). The steric forces present in the various molecular environments are discussed in connection with the degree of phenyl-ring tilt relative to the cyclopentadienyl mean plane and the deviation of the other cyclopentadimyl substituents away from the metal centre. Subsequent reactions of compounds 2.4 and 2.5 are described. Attempts to make linked analogues of the new ligand are summarized in chapter two. In chapter three, two Zr(rV) compounds are prepared, bis (l-phenyl-3-methyl-4,5,6,7-tetrahydroindenyi) zirconium(fV) dichloride, 3.1, and bis (l-phenyl-3-methyl-4,5,6,7-tetrahydroindenyl) dimethyl zirconium(TV), 3.2. Upon crystallization, rac-3.1 spontaneously resolves into crystals containing only one enantiomer. The similarities and differences in the spectroscopic data for the iron(n) compounds of chapter two and the zirconium(IV) compounds of chapter three are discussed and possible explanations offered . The solid state molecular structures of 3.1 and 3.2 were determined by single crystal X-ray diffraction. Experimental details are given in chapter four, whilst the characterizing data are presented in chapter five. Details of the X-ray structure determinations are given in Appendix A.
11
Wardell, E. M. "EXAFS studies on transition metal complexes." Thesis, University of Manchester, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377729.
12
Blunden, Ralph Benedict. "Novel early transition metal cyclopropenyl complexes." Thesis, University of Sussex, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360552.
13
Atkins, Andrew J. "Studies on transition metal macrocyclic complexes." Thesis, University of Edinburgh, 1993. http://hdl.handle.net/1842/11664.
14
Usher, Peter I. "Electrochemical studies of transition metal complexes." Thesis, University of Edinburgh, 1995. http://hdl.handle.net/1842/11492.
Abstract:
This thesis is concerned with the spectroscopic, electrochemical and spectroelectrochemical investigation of a range of transition metal species, all containing the ligand 2,2'-bipyridine (bpy). All the complexes studied exhibit rich electrochemistry and electronic absorption spectra. Chapter one details the electrochemical and spectroelectrochemical techniques used in this work, and presents a brief overview of the reasons why we study transition metal complexes in this manner. Chapter two is concerned with the solvent dependent behaviour of complexes of the form [M(bpy)2(CN)2] (M = Fe, Ru or Os). The electrochemistry, UV/visible spectroscopy and spectroelectrochemistry of these complexes in a range of solvents is described, and both reduced and oxidised forms of the complex are investigated. The solvent dependent characteristics of the complexes are compared with a range of solvent parameters, and show best agreement with Acceptor Numbers. Analysis of epr data for the oxidised complexes, and spectroelectrochemical experiments suggest that the solvent interaction responsible for this behaviour is minimised on removal of an electron. Chapter three details a range of mono- and bi-metallic complexes containing Ru(bpy)2 or Fe(bpy)2 units and poly-aromatic bridging ligands. The electrochemistry UV/visible spectroscopy and spectroelectrochemistry of these complexes is described. Chapter four details the attempted synthesis of three complexes utilising cyanide ligands as a bridge between two metal centres. These complexes are based around either a [Ru(bpy)2(CN)2] or [Pt(bpy)(CN)2] centre. The electrochemistry UV/visible spectroscopy and spectroelectrochemistry of the products is reported, and the likely nature of the products is discussed.
15
Reid, Gillian. "Studies on transition metal macrocyclic complexes." Thesis, University of Edinburgh, 1989. http://hdl.handle.net/1842/12853.
16
Cooper, Glyn. "Photoelectron spectroscopy of transition metal complexes." Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.670392.
17
Chilton, Nicholas Frederick. "Magnetic anisotropy of transition metal complexes." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/magnetic-anisotropy-of-transition-metal-complexes(64b34057-8a7a-44db-a89a-22a233fdefb5).html.
Abstract:
The study of magnetic anisotropy in molecular systems permeates the physical sciences and finds application in areas as diverse as biomedical imaging and quantum information processing. The ability to understand and subsequently to design improved agents requires a detailed knowledge of their fundamental operation. This work outlines the background theory of the electronic structure of magnetic molecules and provides examples, for elements across the Periodic Table, of how it may be employed to aid in the understanding of magnetically anisotropic molecules. The magnetic anisotropies of a series of dimetallic NiII2 complexes and a RuIII2MnII triangle are determined through multi-frequency Electron Paramagnetic Resonance (EPR) spectroscopy and ab initio calculations. The magnetic anisotropy of the former is found to be on the same order of magnitude as the isotropic exchange interactions, while that of the latter is found to be caused by large antisymmetric exchange interactions involving the RuIII ions. An intuitive electrostatic strategy for the prediction of the magnetic anisotropy of DyIII complexes is presented, allowing facile determination of magnetic anisotropy for low symmetry molecules. Through the presentation of the first near-linear pseudo-two-coordinate 4f-block complex, a new family of DyIII complexes with unprecedented Single Molecule Magnet (SMM) properties is proposed. Design criteria for such species are elucidated and show that in general any two-coordinate complex of DyIII is an attractive synthetic target. The exchange interaction between two DyIII ions is directly measured with multi-frequency EPR spectroscopy, explaining the quenching of the slow magnetic relaxation in the pure species compared to the SMM properties of the diluted form. The interpretation of this complex system was achieved with supporting ab initio calculations.
18
Nazir, Ruqia. "Chemistry of transition metal fluoride complexes." Thesis, University of York, 2012. http://etheses.whiterose.ac.uk/2660/.
Abstract:
Metal fluoride complexes that are extremely sensitive to air and water have been characterized by liquid injection field desorption/ionization (LIFDI) mass spectrometry. Dilute solutions of fluoride complexes of nickel, rhodium, titanium, zirconium, hafnium and ruthenium in toluene and tetrahydrofuran were examined by LIFDI methods on a time-of-flight mass spectrometer. All the spectra of nickel, titanium zirconium and hafnium complexes exhibited the molecular ion as base peak. The ruthenium and rhodium complexes showed loss of HF from the molecular ion as base peaks but the molecular ions were easily detected. Two new nickel fluoride complexes are formed by C-F activation reactions with 2,3,5,6-tetrafluoro-4-dimethylaminopyridine and 2,3,5,6-tetrafluoro-4-methoxypyridine yielding 3,5,6-trifluoro-4-dimethylaminopyridine nickel fluoride and 3,5,6-trifluoro-4-methoxypyridine nickel fluoride, respectively. The crystal structure of 3,5,6-trifluoro-4-dimethylaminopyridine nickel fluoride shows typical square planar coordination at nickel with an Ni-F distance of 1.8521(9) Å. pentamethylcyclopentadienyl metal difluoride (metal = Ti, Zr, Hf) complexes were synthesized from the reaction corresponding metal dichloride with NaF. N,N-dimethylethylene-1,2-diamine metal difluoride complexes (metal = Zn, Co, Ni) were synthesized from the reaction of metal difluoride with N,N-dimethylethylene-1,2-diamine. Ruthenium difluoride complexes were prepared from the reaction of ruthenium bis bifluoride complexes with TMAF. The compounds were characterized by multinuclear NMR spectroscopy and LIFDI mass spectrometry. The nickel monofluoride complexes do not provide useful mass spectra by EI or ESI methods. Only the difluoride complexes of titanium, zirconium, hafnium, ruthenium, zinc, cobalt and nickel species showed evidence of the fluoride ligands in the ESI spectra. Collision induced dissociation (CID) was used to investigate the fragmentation pattern of the ions formed in the ESI mass spectrum. It was observed that the ligand attached to the metal has an effect on the fragmentation pattern of complex and the presence of phosphine strengthens the metal fluoride bond. A modified quadrupole mass spectrometer was used to carry out gas phase ion molecule (I-M) reaction of metal ions with liquid and gaseous neutral molecule. Transition metal fluoride complexes did not show evidence of I-M reactions while Re and Mn tricarbonyl complexes have shown 100% conversion to the product. The decay pathway of multiply charged anions (MCAs) of Ti and Zr was also investigated and it was found that these ions decay through ionic fragmentation rather than electron detachment. Hydrogen bonding of pentamethyl cyclopentadienyl difluoride complexes of Ti and Zr with indole and 1,1,1,3,3,3 hexafluoroisopropanol was studied using fluorine NMR spectroscopy. Change in entropy and change in enthalpy were calculated from the equilibrium constant values (K) using Van’t Hoff’s equation.
19
Humphrey, Paul Andrew. "A study of transition metal complexes /." Title page, contents and summary only, 1990. http://web4.library.adelaide.edu.au/theses/09PH/09phh9262.pdf.
20
TOSOLINI, MASSIMO. "Transition Metal Complexes as Anion Carriers." Doctoral thesis, Università degli Studi di Trieste, 2019. http://hdl.handle.net/11368/2962375.
Abstract:
La regolazione del trasporto del cloruro attraverso le membrane biologiche è un processo fondamentale coinvolto in molte vie metaboliche, il cui squilibrio porta a gravi malattie genetiche come la fibrosi cistica. In Natura, il trasporto del cloruro è regolato da complesse proteine di membrana, tuttavia esistono anche alcuni esempi di piccole molecole che fungono da trasportatori di anioni. I trasportatori di cloruro hanno mostrato attività biologiche interessanti (ad esempio antitumorale ed antibiotica) e ne è stato proposto l’utilizzo nella terapia di sostituzione dei canali del cloruro per i pazienti affetti da fibrosi cistica. Quindi, la capacità di sviluppare molecole semplici che siano in grado di promuovere il trasporto del cloruro in membrane biologiche appare molto promettente. In letteratura sono presenti numerosi esempi di trasportatori di cloruro, che generalmente utilizzano (tio)uree come elementi di riconoscimento per l’anione. Al contrario, nonostante sia il riconoscimento che il trasporto di ioni siano tipici processi supramolecolari, ci sono pochi esempi dell'uso di complessi di coordinazione come trasportatori di anioni. Recentemente il nostro gruppo di ricerca ha dimostrato che il complesso di palladio dpppPdCl2 è in grado di promuovere il trasporto di cloruro in liposomi e il progetto di ricerca di questa tesi intende approfondire lo studio dell'attività ionoforica di questi complessi.
Le due proprietà principali che influenzano l'efficienza del trasporto sono la lipofilicità dei trasportatori e la loro affinità per gli anioni. E’ stato quindi condotto uno studio di relazione struttura-attività riguardante questi due parametri sui complessi Pd(II) dppp. La lipofilicità dei complessi di Pd(II) è stata modificata inserendo sostituenti alchilici, mentre l'effetto dell’affinità per il cloruro è stato valutato introducendo gruppi elettron-attrattori e donatori. Inoltre, è stato preso in considerazione il bite angle del legante, un parametro importante che influisce sulla reattività dei complessi di coordinazione. L'attività ionoforica dei complessi è stata studiata utilizzando liposomi come modelli di membrane. I risultati ottenuti indicano che il fattore principale che influenza l'efficienza di trasporto degli ioni è la lipofilicità. Invece, per quanto riguarda il bite angle e la costante di affinità, i loro effetti si sono rivelati più complessi da analizzare. Inoltre, è stato possibile ottenere informazioni sul meccanismo di trasporto promosso da questi ionofori, che è stato confermato essere di tipo carrier elettrogenico o non elettrogenico, a seconda del saggio di trasporto. Lo studio dell’attività ionoforica è stato esteso ad altri metalli, come rame, nichel e platino. Tra questi complessi, quello di Cu(I) si è dimostrato il più efficiente, seppure inferiore a quello di palladio. Ciò ha dimostrato la validità generale dell'approccio aprendo la strada a ulteriori studi. Una seconda parte della tesi si è concentrata sullo studio delle proprietà biologiche di questa nuova classe di ionofori. In collaborazione con la dr.ssa M. Benincasa, la loro attività antimicrobica è stata studiata su batteri Gram-positivi e negativi, mostrando efficacia antibatterica a concentrazioni micromolari contro S. Aureus. Per investigare il meccanismo di interazione degli ionofori con le cellule, sono stati sviluppati ionofori fluorescenti basati su complessi di naftalimmidi o acenaftene con Cu(I) e Pd(II), la cui emissione di fluorescenza sarà utilizzata per avere informazioni circa la loro localizzazione nelle cellule.
Durante il dottorato ho contribuito allo studio dell'attività ionoforica di nuovi peptoidi sintetici preparati dai gruppi di ricerca del prof. F. De Riccardis e la prof.ssa I. Izzo ed ho partecipato allo sviluppo di nuovi materiali elettrocromici basati su naftalimmidi in collaborazione con il prof. J. Parola, dell’Universidade Nova de Lisboa.The regulation of transmembrane chloride transport is a fundamental process involved in many metabolic pathways and its imbalance leads to serious genetic diseases like cystic fibrosis. In Nature, chloride transport is regulated by complex membrane proteins but there are also a few examples of small molecules which act as anion carriers. Chloride transporters have shown interesting biologic activity (e.g. anticancer, antibiotic) and it has been proposed that they could be used in channel replacement therapy for cystic fibrosis patients. In this context, the ability to develop simple molecules able to efficiently promote chloride transport in biological membranes appears really promising. Several examples of artificial chloride carriers are present in literature, usually based on (thio)ureas. On the contrary despite the fact that ion recognition and transport is a typical supramolecular process, there are only a few examples of the use of coordination complexes as anion transporters. Recently our research group reported that a simple bis-phosphine palladium complex, dpppPdCl2, is able to promote chloride transport in liposomes with a carrier mechanism. This represents a completely new class of ionophores and the research project of this Thesis focus on the design and study of the ionophoric activity of Pd(II) based metal complexes. Knowing from literature studies that the lipophilicity of the carrier and its affinity for the anion are the two main properties affecting the transport efficiency, a structure activity relationship study was done on dppp based Pd(II) complexes. The lipophilicity of the Pd(II) complexes was tuned inserting alkyl substituents on the ligands, while the effect of the chloride association constant of the complexes was evaluated by introducing electron-withdrawing and electron-donor substituents on the phenyl rings of the ligand. Moreover, we took into consideration the bite angle of the ligand, which is an important parameter that determines the reactivity of bis-phosphine metal complexes. The ionophoric activity of the compounds was studied with liposomes-based assays. The results indicate that the main factor affecting the ion transport efficiency is lipophilicity. On the other hand, the effects of the bite angle and of the association constant resulted to be more elusive. Moreover, it was possible to gain information on the mechanism of transport promoted by this new class of ionophores, which was confirmed to be an electrogenic or non-electrogenic carrier type mechanism depending on the experimental conditions. The scope of the study was expanded to other transition metals, like copper, nickel and platinum, among which Cu(I) showed the best activity, although lower than palladium. This proved the general validity of the approach and opened the way to further studies on different type of ligands and metal complexes. A second part of the work was focused on the study of the biological properties of this new class of ionophores. In collaboration with dr. M. Benincasa, their antimicrobial activity was tested on Gram-positive and negative bacterias, showing low micromolar efficacy against S. Aureus. With the aim of obtaining information on the mechanism of interaction of the metal-based anionophores with cells, fluorescent ionophores based on naphthalimide or acenaphthene complexes with Cu(I) and Pd(II) were developed. The fluorescence emission of the complexes will be used to localize the complexes inside living cells. Parallel to the development of metal complex based anion carriers, during the course of the Ph.D. period, I have contributed in the study of the ionophoric activity of new synthetic peptoids prepared by professor F. De Riccardis and professor I. Izzo research groups. I have also participated in the development of new electrochromic materials based on naphthalimide phosphine oxides in collaboration with professor J. Parola of the Universidade Nova de Lisboa.
21
Sze-To, Lap, and 司徒立. "The structural chemistry of coordination compounds containing d-block or f-block metals." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B45204470.
22
Getty, April D. "Syntheses and reactivity studies of hydroxo-palladium(II) and amido-platinum(IV) complexes /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/8653.
23
Olson, Michael David. "Pyrazolyl based ligands in transition metal complexes." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/27610.
Abstract:
Several uninegative/ multidentate pyrazolyl based ligands were synthesized [eg. HBPZ₃₋, HBpz”₃₋, MeGapz₃₋/ MeGapz” ₃₋, H2BpZ₂₋/ Me2Bpz₂₋/ Me2GapZ₂₋/ Me2Gapz"₂₋/ Me₂Gapz(OCH₂CH₂NH₂)⁻Me₂Gapz(OCH₂CH₂CH=CH₂)⁻ ; pz pyrazolyl/ pz" = 3, 5 dimethylpyrazolyl].
These ligands were reacted with the sterically hindered metal complex, HBpz*₃MCl (M = Co, Ni; pz* = 3-iPr-4-Br-pyrazolyl) and the mixed-ligand transition metal complexes of general formulae, HBpz*₃ML, were isolated. The X-ray crystal structure of one such complex, HBpz*₃Nipz"₃BH was determined showing a near octahedral arrangement of ligands about the nickel centre. The electronic spectra of the nickel complexes were recorded and compared to predicted transitions. The electronic spectra of the four coordinate nickel complex, HBpz*₃NiCl, fit a d⁸, tetrahedral, ligand field model. The six coordinate complexes, HBpz*₃NiL (L = HBPZ₃, HBpz"₃, MeGapz₃, MeGapz”₃), fit a d⁸, octahedral, ligand field model.
The unsymmetrical pyrazolylgallate ligands were reacted with the rhodium dimer [Rh(CO)₂CI]₂ to give the square planar complexes, LRh(CO) [L = Me2Gapz(OCH₂CH₂NH₂), Me₂Gapz(OCH₂CH₂CH=CH₂)]. These rhodium[I] complexes appeared to undergo oxidative additions of Mel, allylbromide and I₂. Furthermore these rhodium[I] complexes appeared to bind the small gas molecules, CO and ethene.
A number of heterobimetallic complexes, with direct metal-metal bonds, were prepared and isolated from the reaction of the molybdenum anion, HBpz"₃(CO)₃MO⁻ with the transition metal halides, [CuPPb₃Cl]₄, SnR₃Cl (R = Me, Ph) and GePh₃Cl.Science, Faculty of
Chemistry, Department of
Graduate
24
Hyde, Timothy I. "Studies on transition metal tetraaza macrocyclic complexes." Thesis, University of Edinburgh, 1987. http://hdl.handle.net/1842/28273.
25
Skinner, Michael E. G. "Transition metal complexes of diamide-diamine ligands." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365390.
26
Warner, P. "Asymmetric synthesis via transition metal acyl complexes." Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355823.
27
Hyde, T. I. "Studies of transition metal tetraaza macrocyclic complexes." Thesis, University of Edinburgh, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.652780.
Abstract:
A macrocyclic ligand can be regarded as a protecting group for a metal centre, controlling its stereochemical, electronic and redox properties. These properties were examined byulilizing ten 14 membered neutral macrocycles with varying ring substituents and donor groups. A study into the insertion of the platinum metals into four tetraaza 2, 6-pyridyl macrocycles with varying carbon and nitrogen alkylation was instituted. The single crystal X-ray structures of Pd(II), Rh(III), Ru(II) and Ir(III) metal inserted complexes were determined including the species [RuL3(CO)Cl]+ and [IrL4(H)Cl]+ that may be regarded as catalytic intermediates. A comparison of the redox properties of seven Ni(II) and Pd(II) tetraaza macrocycles was studied. Controlled potential electrolysis of [Pd(TMC)]2+, (TMC = 1,4,8,11-tetramethyl 1,4,8,11-tetraazacyclo-tetradecane) at a Pt gauze in acetonitrile afforded a reduction product assigned as a mononuclear Pd(I) complex, [Pd(TMC)]+. The effect of varying one hetero atom donor of a 2,6-diimino pyridyl macrocycle was studied by structural and electrochemical techniques for a series of nickel (II) complexes containing tetraaza, triazaphosphorus and triazathia donor sets. The first reduction product of the triazaphosphorus complex is metal based whereas for the tetraaza complex previous studies had shown the reduction to be ligand based. Reaction of the nickel (I) tetraaza macrocycles (NiL)+, (L = TMC, C rac HMC) with dioxygen in acetonitrile gave the same product as the reaction of [NiL]2+with superoxide ion. With use of isotopic labelling experiments the reactive product was assigned as a nickel (III) - peroxo species, [Ni(III)L(O2)]+.
28
Ball, R. J. "Redox-geometry relationships in transition metal complexes." Thesis, Queen's University Belfast, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273126.
29
Poyraz, Mehmet. "Valence localisation in transition metal cluster complexes." Thesis, University of East Anglia, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389271.
30
Grieves, R. A. "Multinuclear NMR spectroscopy of transition metal complexes." Thesis, University of Bradford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372167.
31
Quelch, Geoffrey E. "Theoretical studies of some transition metal complexes." Thesis, University of Manchester, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329083.
32
Gathergood, Nicholas Keith Peter. "Chiral cyclopentadienyl lanthanide and transition metal complexes." Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284648.
33
Maah, M. J. "Transition metal complexes derived from phospha-alkynes." Thesis, University of Sussex, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381631.
34
Sheridan, J. B. "The reactions of transition metal hydrocarbon complexes." Thesis, University of Bristol, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356238.
35
Green, G. "Transition metal oxo-complexes as organic oxidants." Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/37711.
36
Keane, Theo. "Non-adiabatic effects in transition metal complexes." Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/15948/.
37
Sadler, Andrew John. "Transition metal complexes for solar fuels applications." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/22826/.
38
Seidel, Scott William 1971. "Transition metal complexes containing chelating amido ligands." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/47411.
39
Geary, Elaine A. M. "Transition metal complexes as solar cell dyes." Thesis, University of Edinburgh, 2005. http://hdl.handle.net/1842/12198.
Abstract:
Dye-Sensitised Solar Cells (DSSC) were first reported in the early 1990’s and function by the sensitisation of a semiconductor using a dye molecule such as organic and transition metal organometallic dyes. This thesis reports the synthesis and characterisation of transition metal dyes with applications as sensitisers in DSSC. Complexes of Ni, Pd and Pt were investigated for use in standard liquid electrolyte cells and Donor-Acceptor type solid-state solar cells. A family of [Pt(II)(diimine)(dithiolate)] complexes of general formula [Pt{X,X’(CO2R)2-bpy}(mnt)] (where X=3, 4 or 5; R=H or Et, bpy = 2,2’-bipyridyl and mnt = maleonitriledithiolate), have been synthesised, spectroscopically and electrochemically characterised and attached to a TiO2 substrate to be tested as solar cell sensitisers. A single crystal X-ray structure showing a large torsion angle between the bipyridyl rings was determined for [Pt{3,3’(CO2Et)2-2,2’-bpy}(mnt)].MeCN. The effect of changing the position of the bpy substituents from 3,3’ to 4,4’ and 5,5’ is discussed with reference to structural and electronic changes seen within the different members of the family of molecules. The UV/Vis/NIR and in-situ EPR spectroelectrochemical studies of the family and its related precursor molecules are discussed. All three complexes (where R=H) were tested as solar cell sensitisers with the 3,3’-disubstituted bpy complex giving an intermediate dye loading value but superior photovoltaic performance to those of the other two. The performance of this sensitiser is then compared with that of a well known Ru(polypyridyl) sensitiser. A family of unsymmetrical [Ni(II)(dithione)(dithiolate)] complexes of general formula, [Ni(R1R2pipdt)(dmit)], where R = Me, Bz and Pri, pipdt = 1,4-disbustituted-piperazine-3,2-dithione and dmit = 1,3-dithiole-2-thione-4,5-dithiolate, have been synthesised and characterised and investigated for use in solid-state solar cells. electrochemistry and UV/Visible spectroscopy results show that the reduction potential of a complex is related to the number of aromatic substituents on the pipdt ligand. The dibenzyl substituted complex shows the largest absorption wavelength in the NIR which is attributed to it having the smallest HOMO-LUMO gap of the complexes studied. In-situ EPR results show the reduction electron to be located on the R1R2pipdt ligand which confirms previous proposals that the LUMO is in part located on this part of the complex. Raman spectroscopy confirms the dmit ligand to be formally dianionic with the R1R2pipdt having a formally neutral charge.
40
Halcrow, Malcolm A. "Studies on transition metal polythia macrocyclic complexes." Thesis, University of Edinburgh, 1991. http://hdl.handle.net/1842/14961.
Abstract:
An introduction to macrocyclic coordination chemistry is presented and the general aims of the project are discussed. The syntheses and structural characterisation of the dimeric bi-octahedral complexes [Ni2(S4)2(μ-Cl)_2]^2+ (S_4 = [12]aneS_4, [14]aneS_4, of [Ni(H_2O)_6)]^2+ by [12]aneS_4 and [16]aneS_4 is discussed: [Ni[16]aneS_4)-(OH_2)_2]^2+ exhibits a trans-octahedral stereochemistry by x-ray crystallography. The syntheses and characterisation of the five-coordinate complexes [Ni([9]aneS_3)(PP)]^2+ (PP = diphosphine chelate) are presented. Four complexes in the series have been shown to adopt square-pyramidal geometries by single crystal x-ray analysis. The synthesis and single crystal structure of the square-pyramidal species [Ni([15]aneS_5)]^2+ is also described. [Ni([15]aneS_3)]^2+ forms six-coordinate adducts with Cl^-, CH_3CN and pyridine. An electrochemical study of the complexes [Ni([9]aneS_3)(PP)]^2+ is given. The reduction products [Ni([9]aneS_3)(PP)]^+ and [Ni([9]aneS_3)(PP)]^0 can be generated reversibly from the Ni^II precursors, and were assigned as square-pyramidal d^9 Ni^I and tetrahedral d^10 Ni^0 species respectively. The reaction of [Ni([9]AneS_3)(PP)]^+ with CO is investigated. The characterisation of the redox products of [Ni([9]aneS_3)_2]^2+ is also discussed: [Ni([9]aneS_3)_2]^3+ was formulated as an octahedral d^7 Ni^III complex. The synthesis and characterisation of the compounds [Rh([9]aneS_3)-(L)(L')]^+ (L,L' = C_2H_4, 0.5C_7H_8, 0.5C_8H_12, 0.5C_4H_6, CO, PR_3) is given. Single crystal x-ray analyses on four of these complexes show them to adopt a variety of five-coordinate geometries. The [Rh([9]aneS_3)]^+ fragment is shown to have high electrophilic character. Reactions of [Rh([9]aneS_3)-(L)(L')]^+ with electrophilic and nucleophilic substrates are discussed. The preparation and properties of the complexes [Ir([9]aneS_3)(L)(L')]^+ (L,L' = C_2H_4, C_8H_14, 0.5C_8H_12, 0.5C_4H_6, CO, PPh_3) are described. Three of these species are shown to have five-coordinate structures by x-ray crystallography. The electronic character of the species [M([9]aneS_3)(L)_2]^+ (M &61 Rh, Ir; L = C_2H_4, 0.5C_4H_6) is discussed. X-ray structural analyses of [16]aneS_4 show this ligand to adopt a rectangular conformation in the solid state. Molecular mechanics calculations on [16]aneS_4 and C_16H_32 are presented.
41
Taylor, Anne. "Studies of transition metal thioether macrocyclic complexes." Thesis, University of Edinburgh, 1991. http://hdl.handle.net/1842/14528.
Abstract:
Chapter 1: A general discussion of macrocyclic co-ordination chemistry is given, with particular emphasis on the biological and catalytic relevance of macrocyclic systems. Chapter 2: Reproducible high yield synthesis of [Au ([9]aneS3)2](PF6) and [Au([9]aneS3)2](BF4)2 have been established. [Au([9]aneS3)2]2+ undergoes a one-electron oxidation to Au(III) and an irreversible reduction to Au(I). The solution e.p.r. spectrum of [Au([9]aneS3)2]2+ shows an isotropic signal with hyperfine coupling to 197Au. The frozen glass e.p.r. spectrum depicts a complicated anisotropic signal. Attempted e.p.r. spectrum simulation suggested that the quadrupole and nuclear Zeeman interactions are significant in [Au([9]aneS3)2]2&43 , consistent with the 197Au Mossbauer data recorded for Au(II) complex. The stable Au(I) complex, [Au(PPh3)([9]aneS3)](PF6) was also prepared. Chapter 3: [Au([18]aneS6)[(PF6) was isolated and structurally characterised; [18]aneS6 binds the Au(I) centre in a [2+ 2] distorted tetrahedral co-ordination. This complex exhibits two quasi-reversible oxidations, which were assigned as being largely metal-based processes by e.p.r. spectroscopy. Electrogenerations of the Au(II) and Au(III) species were monitored by electronic absorption spectroscopy, which demonstrated the absence of any transient intermediates. The electron-transfer rate constant determined for the [Au([18]aneS6)]+ /2&43 couple indicates that a large stereochemical change accompanies the oxidation of Au(I) and Au(II). Direct synthesis of [Au([18]aneS6)](PF6)2 was carried out. The solution e.p.r. spectrum of [Au([18]aneS6)](PF6)2 in MeNO2, at 293K shows an isotropic signal; a complicated isotropic signal is observed at 77K. On the basis of e.p.r. and electronic absorption spectra the geometry of [Au([18]aneS6)]2+ was proposed to be distorted octahedral. Chapter 4: The Au(I) complex of [15]aneS5 was isolated. [Au([15]aneS5)](B(C6F5)4) and [Au(15]aneS5)](PF6) are both dimeric in the solid-state, with the Au(I) centres in [2+ 2] distorted tetrahedral stereochemistries and bound in an exocyclic manner between the two facial macrocycles. [Au([15]aneS5]2+ exhibits two solvent dependent quasi-reversible oxidations, which were assigned as largely metal-based processes. The electron-transfer rate constant, ks, for the first oxidation was determined. Electrogenerations of the Au(II) and Au(III) species were monitored using the O.T.E. technique. [Au([15]aneS5)](PF6)2 was synthesised and was found to be monomeric in solution. An isotropic e.p.r. spectrum was observed for [Au([15]aneS5)]2+ in MeNO2 solution. A solvent independent rhombic signal was recorded at 77K, the d9 centre is therefore in an unsymmetrical environment. The dimeric [Au([15]aneS5)]+ solid must either immediately dissociate on solvation or prior to or on oxidation to [Au([15]aneS5)]2+ .
42
Nilchi, A. "Selective hydrogenation catalysed by transition metal complexes." Thesis, Kingston University, 1988. http://eprints.kingston.ac.uk/20518/.
Abstract:
This work is an investigation of the mechanism by which norbornadiene, methyl oleate and methyl linoleate are hydrogenated in acetone at 30[sup]oC, 1 atmosphere or 3 atmospheres pressure, using rhodium complexes of the type [Rh(diene)L[sub]n][sup]+A[sup]-(where diene = norbornadiene , L = tertiary phosphine, phosphite, A = CIO[sup]-[sub]4 or PF[sup]-[sub]6). The results were interpreted assuming three active catalyst species, (Rh(diene)L[sub]2)[sup]+, (RhH[sub]2L[sub]2)[sup]+ and RhHL[sub]2. Also investigated were the effects of adding acid (HClO[sub]4) or base (Net[sub]3) and how this altered the equilibrium (RhH[sub]2L[sub]2)[sup]+<--> H[sup]+ + RhHL[sub]2. At atmospheric pressure, the rate of hydrogenation of norbornadiene and norbornene varies with ligand in the order PPh[sub]3 < PPh[sub]2Me < PPhMe[sub]2, suggesting that oxidative addition of hydrogen is an important first stage of the catalysis. The addition of acid, slowed the rate of hydrogenation for catalysts containing more electron donating ligands (relative to triphenyl phosphine), indicating that the monohydride was a more active specie than the dihydride. With triphenylphosphine or less electron donating ligands in the catalyst, the rate remains constant or increase slightly, indicating that an "unsaturate route" emanating from a diene complex is probably important. The catalyst containing cyclohexylphosphine ligands which are strongly electrondonating but sterically crowded is ineffective in hydrogenation, suggesting that steric crowding may cause an alternative route to operate. Higher pressure (3 atm.) causes faster hydrogenation and provided other mechanistic insights. For methyl oleate at atmospheric pressure, the rate of hydrogenation varies with ligand in the order PPh[sub]3 > PPh[sub]2Me > PPhMe[sub]2, but this order is reversed at 3 atm. pressure. The rate of isomerisation of methyl oleate varies with ligand in the order PPh[sub]3 < PPh[sub]2Me < PPhMe[sub]2, at both pressures. The rate of isomerisation of methyl oIeate and methyl linoleate is lowest, when there is no or a slight excess of acid present but is highest in presence of a base (especially for the catalyst containing diphenylmethylphosphine ligand). Mechanistic interpretations were made.
43
Wilson, F. I. C. "Reactions of some dinuclear transition metal complexes." Thesis, Kingston University, 1988. http://eprints.kingston.ac.uk/20522/.
Abstract:
The work in this thesis consists of three related studies. (i) Further investigations have been made into the mechanism of the photochemical reaction between (Mn[sub]2(CO)[sub]8{PBu[sub]3}[sub]2) and benzyl halides, equation 1. A previous study in these laboratories, which included an (Mn[sub]2(CO)[sub]8{PBu[sub]3}[sub]2) + PhCH[sub]2Cl -->(MnCl(CO)[sub]4PBu[sub]3) + (Mn(PhCH[sub]2)(CO)[sub]4PBu[sub]3) 1 examination of reaction kinetics, led to the suggestion that the mechanism involved CO dissociation from the manganese dimer, followed by metal-metal bond homolysis and subsequent reaction of the 15-electron intermediate, (Mn(CO)[sub]3PBu[sub]3, with benzyl chloride. The present work begins with the realisation that the previous data is also compatible with a radical chain process. In an attempt to distinguish between these two mechanisms, studies have been make of the variation in the quantum yield for the formation of (MnCl(CO)[sub]4PBu[sub]3) with benzyl chloride concentration. An examination of the reaction between (Mn[sub]2(CO)[sub]8DPPM) and benzyl chloride has also been carried out. Unfortunately, these studies still do not provide an unambiguous distinction between the mechanisms. (ii) A study has been made of the thermal reaction between (Mn[sub]2(CO)[sub]8a{PBu[sub]3}[sub]2) and benzyl and other halides. At 40 C the reaction is first order in both manganese dimer and benzyl choride and is not inhibited by added CO. This contrasts with that previously reported for the photochemical reaction and indicates that the thermal reaction follows a different pathway. Reaction of the metal dimer with 6-bromo-hex-1-ene suggests a free radical process and reactions with substituted benzyl bromides indicate an electron transfer step. Thus a mechanism is proposed involving electron transfer from the dimer to the organic halide, as the first step. Subsequent fission of the radical anion so formed into a halide ion and an organic radical, such as PhCH2, is followed by reaction of the dinuclear radical cation with the halide ion generating (MnCI(CO)[sub]4PBu[sub]3) and (Mn(CO)[sub]4PBu[sub]3). The manganese-centered radical then combines with the benzyl radical to yield (MnBz(CO)[sub]4PBu[sub]3). This reaction is thus a non-chain process. (iii) In view of the findings detailed above that (Mn[sub]2(CO)[sub]8{PBu[sub]3}[sub]2) reacts with benzyl chloride according to equation 1, it was deemed appropriate to examine the reactions between benzyl halides and a range of dinuclear metal complexes. The complexes studied were (M[sub]2(CO)[sub]10) (M = Mn, Re), (Mo[sub]2(CO)[sub]6Cp[sub]2), (Fe(CO)[sub]2Cp)[sub]2, (Fe[sub]2(CO)[sub]3PBu[sub]3Cp[sub]2), (Fe(CO){P(OMe)[sub]3}Cp)[sub]2 and (Co[sub]2(CO)[sub]6{PBu[sub]3}[sub]2), (Cp = D[sup]5-C[sub]5H[sub]5). Only (Fe[sub]2(CO)[sub]3PBu[sub]3Cp[sub]2) reacted with benzyl chloride under thermal conditions. All the dimers, except (M[sub]2(CO)[sub]10) (M = Mn, Re), reacted with benzyl bromide giving the corresponding bromo-complexes. Photochemical reactions with benzyl chloride were observed for all dimers except (Co[sub]2(CO)[sub]6{PBu[sub]3}[sub]2) and all, including the cobalt complex, reacted with benzyl bromide. In all cases, halo-complexes were formed, however, the observation of the associated benzyl complexes depended on both the benzyl halide and the metal dimer.
44
Holmes, Kathryn E. "Structural diversity within transition metal-sulfimide complexes." Thesis, Loughborough University, 2003. https://dspace.lboro.ac.uk/2134/35645.
Abstract:
S,S'-diphenylsulfimide, Ph2SNH, 1, is an excellent ligand that readily forms N-bound complexes with a range of transition metals. Its importance as a ligand is enhanced by two significant features of the resulting complexes: (1) the strong hydrogen bonding interactions between the NH unit and the counterions; and (2) the ligand's ability to stabilise unusual structural combinations. By varying the counterions, the hydrogen bonding pattern can be changed and this affects the geometry at the metal centre. The anion also plays an important role in determining the coordination number of the metal. The hydrogen bonding interactions have been utilised to prepare extended arrays by the inclusion of appropriate outer sphere, bridging ligands, such as terephthalate and fumarate into the system. The fixation of atmospheric CO2 has been observed in a number of systems leading to the formation of both a bicarbonate dimer and a metal-bound carbonate ligand. These act as hydrogen bonding acceptors to give extended 2-D networks.
45
Silber, Georg Thomas. "Molecular semiconductors based on transition metal complexes." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/18018.
Abstract:
The field of organic, or molecular, electronics is currently dominated by both polymeric and molecular organic materials, while considerably less research efforts are devoted to transition metal based complexes. Despite this, such compounds can offer advantages including additional tuneability of the spatial distribution and energy levels of the frontier orbitals or stable paramagnetic species by manipulating the metal-ligand interactions which may be accomplished selectively modifying the ligand framework or changing the central metal. A series of Ni(II) and Cu(II) acenaphthenequinone bis(thiosemicarbazonato) complexes were prepared and characterised using X-ray diffraction, cyclic voltammetry, UV/Vis and EPR spectroscopy, as well as magnetic susceptibility and field effect transistor measurements and computational calculations. The observed charge transport properties are discussed in terms of the structural and electronic trends both within the series and in the context of the two more established analogue series, namely the bis(3-thiosemicarbazonato) and the diacetyl bis(3-thiosemicarbazonato) metal complexes. The Ni(II) analogues of the acenaphthenequinone bis(thiosemicarbazonato) family were found to exhibit p-type charge transport with mobilities between 10¯9 and 10¯5 cm2V¯1s¯1 depending on the exocyclic substitutent and resulting packing pattern. The observed results were rationalised in terms of the reorganisation energy and the charge transfer integrals. A series of 4,4`-phenyl-substituted nickel dithiolene complexes was synthesised and characterised. Initially with the aim of investigating the effect of varying the para-substituent of the phenyl ring on the charge transport properties, these efforts were undermined by the poor processability of these molecules by both vapour and solution phase methods. As a result, n-type charge transport could be observed under ambient conditions only for the phenyl and 4-bromo-phenyl substituted analogues, but the device performance was extremely poor. Nonetheless, the calculated reorganisation energies, charge transfer integrals and predicted mobilities were encouraging and may prompt further work on these materials. An all-organic analogue series of 4,4`-(4-halogen-phenyl)-substituted tetrathiafulvalenes was also investigated. The hole transport materials displayed mobilities of between 10¯3 and 10¯7 cm2V¯1s¯1 for both solution and vapour processed devices, depending on the nature of the halogen. These results are discussed in terms of their molecular properties and the calculated charge transport parameters and put in context of the performance of the 4,4`-bis(phenyl)-substituted benchmark analogue. Interestingly, the obtained crystal structure of the bromo-substituted analogue showed the molecule to be in the cis conformation, an observation that is unprecedented for simple, 4-phenyl,5-hydrogen substituted tetrathiafulvalenes, and indicates that both conformers are initially formed. Finally, a series of 4,4`-(2-alkyl)thienyl substituted nickel dithiolene salts and tetrathiafulvalenes was synthesised and characterised. While the charge transport properties of the former were not further investigated due to the low solubility of the neutral species, the tetrathiafulvalenes were incorporated into FET devices via solution processing. All exhibited comparatively high conductivity at room temperature (1.6x10¯3S m¯1), exceeding that of their quarterthiophene analogues. This masked the observed gate effects but indicates potential applications as conducting or charge transfer materials. While the two resolved analogues displayed trans geometry in the single crystal structures, powder diffraction and preliminary DSC measurements indicate that the materials displayed at least one additional phase, which once again likely corresponded to the cis conformer.
46
Lin, Bing. "Organometallic chemistry of transition metal polyyne complexes." Thesis, University of Cambridge, 1993. https://www.repository.cam.ac.uk/handle/1810/272565.
47
Meade, Thomas Joseph. "Inclusion complexes of molecular transition metal hosts /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487262513406675.
48
Chappell, Sarah. "Transition metal terpyridine complexes for molecular electronics." Thesis, University of Liverpool, 2014. http://livrepository.liverpool.ac.uk/2011084/.
Abstract:
Currently there is a huge amount of interest in the synthesis and electrical characterisation of single molecules that have the potential for use in electronic devices. In order for this technology to move forward it is necessary to gain insights into structure-property relationships at the nanoscale, as well as a basic understanding of the charge transport through various molecular architectures. It has previously been demonstrated that the electrical properties of redox active single molecules can be investigated as a function of potential. This thesis investigates the single molecule conductance properties of molecules incorporating a transition metal centre. The research presented in this thesis investigates two major studies. The first is a study into the electrochemical and conductance properties of a variety of transition metal based complexes. Initial electrochemical and conductance investigations of a series of pyterpy transition metal complexes showed a similar conductance for all the series, this was investigated in two different environments. The ligand was then varied and several ruthenium complexes were investigated, to investigate the anchoring group effect and to examine the length and conductance relationship. The data presented here demonstrates a higher conductance for methyl sulphide anchoring group than the pyridyl anchoring group. The data presented showed a low dependence on molecular length, suggesting a hopping transport mechanism. The conductance behaviour of two [M(pyterpy)2](PF6)2 complexes were investigated as a function of potential in an ionic liquid medium. The data presented exhibited an increase in conductance as the redox potential was reached. The second study investigated the conductance behaviour of two 6-porphyrin nanorings. This is the first conductance study on these porphyrin based complexes. The study investigated a ‘complete’ and ‘broken’ nanoring and showed a smaller than expected difference in conductance between them. This preliminary study has allowed for the development of the structure to investigate possible quantum interference effects.
49
Merle, Nicolas. "Transition metal complexes of chelating phosphine boranes." Thesis, University of Bath, 2006. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426296.
50
Fuse', M. "CHIRAL TRANSITION METAL COMPLEXES: SYNTHESIS, CHARACTERIZATION, APPLICATIONS." Doctoral thesis, Università degli Studi di Milano, 2015. http://hdl.handle.net/2434/332272.
Abstract:
The main target of this thesis was the investigation of different
aspects of the chirality at the metal centre. In particular we studied
stereo-specific synthesis of octahedral transition metallic complexes
or their resolution in enantiomeric pure form, in order to evaluate
the influence of the chirality at the metal centre in different fields
such as: catalysis, emission or interaction with chiral environment.
The use of chiral-at-metal complexes in catalysis is somewhat less
common than that of other chiral organometallic architectures. Via
stereospecific reaction, we were able to obtain ruthenium(II) complexes
of general formula [Ru(NN)(PP)Cl2] in optically pure form,
where NN was a chiral diamine and PP was a chelating or two
mono phosphines. These complexes, after the activation into the hydride
species, were active catalysts for the reduction of ketones via
asymmetric transfer hydrogenation. We observed that, in complexes
where two chiral ligands were simultaneously present, the third chirality
that located at the metal centre was prevalent in the definition
of the configuration of the products.
In order to introduce the planar chirality, we synthesised different
complexes of the types [h6-arene-Ru(NN)Cl], however in the most
cases intractable complex mixture of stereoisomers were obtained.
This results prompted us to explore different techniques able to describe
complex mixtures of complexes with several type of chirality
involved.
VCD in tandem with DFT calculation is powerful technique for
the determination of the absolute configuration and conformational
analysis; despite new results concerning transition metal complexes
are coming out, their application in the study of metallorganic compounds
are not common. The strength of IR and VCD spectroscopy
lies in the fact that the spectra of a chiral molecule contain sufficient
stereochemical details to be consistent with only a single absolute
configuration and an unique solution-state conformation, or distribution
of conformations, of the molecule; moreover compared with
ECD the DFT calculation is more reliable.
For our purpose we selected three common motifs in organometallic
chemistry never investigated by VCD spectroscopy. We decided to investigate the carbon monoxide as the first chromophore;
carbon monoxide is one on the most common ligand for
transition metal complexes; the carbonyl complexes found application
as catalysts, precatalysts or stoichiometric reagents in many different
reactions. Therefore we synthesised and resolved a series of
of heteroleptic ruthenium (II) cyclopentadienyl complexes.
The second chromophore was a metal-hydride, which has important
role in catalytic reduction. We were able to synthesis one
Ru(II) hydride complex as single enantiomer that was completely
and whose metal chirality was highlighted by VCD.
The third class of compounds was the cyclometallated iridium(III)
complexes that due to their photophysical properties have been extensively
studied in the last years, founding application in several
fields. Here the chromophore was constituted by two orthometalled
phenylpyridine coordinated at the metal in helical shape.
In this latter case, our interest was also adressed to study the photophysical
properties of the different diastereomers and in order to
verify if the emission could be influenced by the diastereomeric nature
of the complexes. In spite of that in solution no differences were
highlighted, we found that the different packing of the enantiomers
and stereoisomers produces aggregates with different emitting properties.
By VCD spectrometry integrated with DFT calculation we were
able to identify the characteristic features of the different stereogenic
centre present in the complexes. In the CO and Ir(III) complexes we
also investigated the origin of the VCD sign. VCD spectroscopy
proved to be a valuable and powerful technique when applied to
metallorganic chromophores, moreover the results of these investigations
appear in the literature and here for the first time.