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Claudio, Mendicute Fierro. "Synthesis of nickel-thiolate complexes." Thesis, Manchester Metropolitan University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403779.
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Hou, Hongyi. "Small molecule activation by nickel complexes /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2004. http://wwwlib.umi.com/cr/ucsd/fullcit?p3142457.
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Barnes, Alan. "Studies in unsymmetrical nickel BIS(dithiolene) complexes." Thesis, University of Huddersfield, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338598.
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Charra, Valentine. "Coordination of multidentate N-heterocyclic carbene ligands to nickel." Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAF019/document.
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Le sujet de cette thèse porte sur la synthèse de ligands de type bis-NHC (carbène N-Hétérocyclique) et leur réactivité vis-À-Vis des complexes d’argent(I), de cuivre(I) et de nickel(II).Après avoir exploré les différentes méthodologies de synthèse des complexes de nickel(II) bis-NHC, le but était de tester leurs activités en catalyse d’oligomérisation de l’éthylène. Une série de nouveaux complexes d’argent(I) et de cuivre(I) fut synthétisée. Cinq voies furent testées pour la formation de complexes de nickel. Les résultats les plus probants furent obtenus par transmétallation à partir des complexes d’iodure ou de bromure d’argent(I)<br>The purpose of this work was the synthesis of bis-NHC (N-Heterocyclic carbene) ligands, theformation of the corresponding silver(I), copper(I) and nickel(II) complexes and the assessment ofthe catalytic activity of the bis-NHC nickel(II) complexes in ethylene oligomerization. A series of new bis-NHC silver(I) and copper(I) complexes was synthesized. Five different synthetic routes were tested for the formation of nickel(II) bis-NHC complexes. The most significant results were obtained by transmetalation from the silver(I) iodide or bromide complexes
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Hussain, Mazhar. "Cyclopentadienyl nickel complexes bearing a pendant phosphane tether." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=979445892.
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Jupp, Kathleen M. "Dynamically sourced intensity in octahedral nickel(II) complexes." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241013.
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Autissen, Valerie. "Studies on the protonation mechanisms of nickel complexes." Thesis, University of Newcastle Upon Tyne, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420069.
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Brechin, Euan K. "Polynuclear nickel and cobalt complexes of pyridonate ligands." Thesis, University of Edinburgh, 1997. http://hdl.handle.net/1842/15324.
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Schneck, Felix. "Proton-Coupled Electron Transfer at Nickel Pincer Complexes." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2019. http://hdl.handle.net/11858/00-1735-0000-002E-E64C-9.
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Filatre-Furcate, Agathe. "Conducteurs moléculaires neutres : complexes bis (dithiolène) d'or et de nickel." Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S143.
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Au cours de ce travail, nous nous sommes particulièrement intéressés à une classe de molécules électroactives précurseurs de matériaux moléculaires conducteurs à composant unique, les complexes bis(1,2-dithiolène) d'or et de nickel neutres. Nous avons tout d'abord développé une série originale de complexes radicalaires d'or [Au(R-thiazYdt)2] à partir de ligands dithiolène, riches en électron, les N-alkyl-1,3-thiazoline-2-chalcogénone-4,5-dithiolate (R-thiazYdt)2 avec Y = O, S, Se et R = Pr, iPr, cycloPr, NMe2. Le substituant R de l'hétérocycle joue un rôle majeur sur les propriétés des matériaux, résultant des interactions électroniques intermoléculaires entre ces complexes paramagnétiques. Les complexes de nickel diamagnétiques, [Ni(R-thiazSdt)2], des mêmes ligands dithiolène, présentent quant à eux une organisation à l'état solide très différente, conséquence de leur caractère à "couche fermée". Enfin, la réactivité originale des dérivés avec R = tBu conduit à des ligands dithiolène portés par un cycle aromatique 2-alkylthio-thiazole (RS-tzdt). Leurs complexes d'or neutres [Au(RS-tzdt)2] forment des empilements fortement dimérisés et semi-conducteurs<br>During this work, we particularly focused on one type of electroactive molecules, precursors of single component molecular conductors, the neutral gold and nickel bis(1,2-dithiolene) complexes. First we developed a series of radical gold complexes [Au(R-thiazYdt)2] derived from electron rich dithiolene ligands, the N-alkyl-1,3-thiazoline-2-chalcogenone-4,5-dithiolate (R-thiazYdt)2 with Y = O, S, Se and R = Pr, iPr, cycloPr, NMe2. The R substituent plays an important role on the properties of these materials resulting from the intermolecular electronic interactions between these paramagnetic complexes. Besides, diamagnetic nickel complexes, [Ni(R-thiazSdt)2], with the same dithiolene ligands exhibit a different organization in the solid state, a consequence of their closed shell nature. Finally, the original reactivity of the derivatives with R = tBu leads to dithiolene ligands with an aromatic 2-alkylthio-1,3-thiazole ring (RS-tzdt). Their neutral gold complexes [Au(RS-tzdt)2] form semi-conducting strongly dimerized stacks
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Mwania, Tom Muinde. "Synthesis and characterization of nickel imine/amine complexes; a possible model for nickel superoxide dismutase." Thesis, Wichita State University, 2012. http://hdl.handle.net/10057/5416.
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Superoxide dismutases are ubiquitous enzymes that efficiently catalyze the disproportionation of superoxide radical anions to protect biological molecules from oxidative damage. Several SODs have been identified having different metals at their active sites. These include Mn SOD, Fe SOD, Cu/Zn SOD and, most recently, Ni SOD. The catalytic center of Ni SOD resides in the N-terminal active-site loop, where a Ni(II) is coordinated by the amine N of His-1, the amide N of Cys-2, and two thiolate S atoms of Cys-2 and Cys-6. In the oxidized form, Ni(III) adds the imidazole N of His-1 as an axial ligand. For the past decade, we have been developing methodology using 2, 2’-dithiodibenzaldehyde (DTDB) for the synthesis of metal complexes with mixed N/S coordination. We are reporting on the application of this methodology to the synthesis of model complexes for the active site of NiSOD, in which we have successfully synthesized and characterized three NiIIN2S2 complexes of imine/amine N donors: Ni(NNS)SPh (1), Ni(NNS)SPhNO2 (2) and Ni(NNS)StBu (3). These may be used as a model for reduced NiSOD, with future plans of comparing to complexes with amide/amine N donors, thus establishing the role of the amide.<br>Thesis (M.S.)--Wichita State University, College of Liberal Arts and Sciences, Dept. of Chemistry
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Silcock, Peter J. "Nickel and palladium complexes of di-N-heterocyclic carbenes." Thesis, University of Oxford, 1999. https://ora.ox.ac.uk/objects/uuid:679dade4-1d16-4918-b155-996250516783.
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This thesis is concerned with the synthesis of two di-N-heterocyclic carbene ligands, and their reactivity towards nickel and palladium precursors in order to synthesise new organometallic pre-catalysts for a number of important reactions. The catalytic properties of a new rhodium C<sub>60</sub> compound are also investigated, with relevance to the evaluation of C<sub>60</sub> as a hydrogen storage medium. <b>Chapter 1</b> reviews the preparation and chemistry of N-heterocyclic carbenes, emphasising their organometallic reactivity and role as ancillary ligands in homogeneous transition metal catalysis. An overview of relevant nickel and palladium catalysis is also presented, including olefin polymerisation, olefm / CO copolymerisation and Heck coupling reactions. <b>Chapter 2</b> describes the synthesis and characterisation of the dicarbene ligands <sup>tBu</sup>CC<sup>meth</sup> and <sup>tBu</sup>CC<sup>eth</sup> and their reactions with various nickel precursors in attempts to prepare chelating dicarbene nickel cis-dihalide complexes. The synthesis, characterisation and chemical reactivity of the cations [Ni(<sup>tBu</sup>CC<sup>meth</sup>)<sub>2</sub>]<sup>2+</sup>, [(<sup>tBu</sup>CC<sup>meth</sup>)NiCl(PMe<sub>3</sub>)] <sup>+</sup> and [(<sup>tBu</sup>CC<sup>eth</sup>)NiCl(PMe<sub>3</sub>)]<sup>+</sup> is detailed, and their X-ray structures are compared. The unsuccessful preparation of [Ni(<sup>tBu</sup>CC<sup>eth</sup>)<sub>2</sub>] <sup>2+</sup> and the relative stability of the monocations with respect to dicarbene substitution is discussed and attributed to steric factors. <b>Chapter 3</b> describes the synthesis, characterisation, reactivity and catalytic studies of simple nickel and palladium cis-dimethyl complexes of the chelating dicarbene ligands. Variable temperature <sup>1</sup>H NMR spectroscopy showed contrasting rates of thermal hydrocarbon elimination from Ni(<sup>tBu</sup>CC<sup>meth</sup>)Me<sub>2</sub> and Ni(<sup>tBu</sup>CC<sup>eth</sup>)Me<sub>2</sub>, which has previously been observed for chelating bis-phosphine analogues with various P,P' linkages (CH<sub>2</sub>)<sub>n</sub> . These observations further corroborate the analogy between dicarbene and 6/s-phosphine ligands. It was demonstrated that the compounds Pd(<sup>tBu</sup>CC<sup>meth</sup>)Me<sub>2</sub>and Pd(<sup>tBu</sup>CC<sup>eth</sup>)Me<sub>2</sub> are effective pre-catalysts for the Heck coupling of 4-bromoanisole and n-butyl acrylate. In addition cations of the type [(<sup>tBu</sup>CC<sup>meth/eth</sup>)PdMe(L)]<sup>+</sup> (L = pyridine, THF) which are relevant to olefin / CO copolymerisation were prepared. The X-ray structures of M(<sup>tBu</sup>CC<sup>eth</sup>)Me2 (M = Ni, Pd) are discussed as well as the synthesis and structural characterisation of [(|Li-tBu CC meth){Ni(PMe<sub>3</sub>)Me<sub>2</sub>}<sub>2</sub>]. <b>Chapter 4</b> presents a brief introduction to some relevant C<sub>60</sub> chemistry and to the concept of hydrogen storage. The synthesis and characterisation of a new rhodium Ceo compound is described. The compound catalysed the hydrogenation and hydroformylation of simple alkenes as well as the hydrogenation of C<sub>60</sub> to C<sub>60</sub>H<sub>36</sub> . The recovery of hydrogen gas from C<sub>60</sub>H<sub>36</sub> was investigated in order to evaluate C<sub>60</sub> as a hydrogen storage medium. <b>Chapter 5</b> outlines the experimental details for the synthesis, characterisation, reactions and catalytic studies of the new compounds described in the preceding three chapters. <b>Chapter 6</b> presents the characterising data for the new compounds described in chapters 2 and 3. <b>Appendices</b> contain details of the crystallographic data for the eight structurally characterised compounds described in chapters 2 and 3.
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Karim, Salma. "Preparation and characterization of supported and unsupported nickel complexes." Thesis, Brunel University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.290951.
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Brehin, E. K. "Polynuclear nickel and cobalt complexes of substituted pyridone ligands." Thesis, University of Edinburgh, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.641920.
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This thesis presents routes to several high nuclearity nickel and cobalt complexes of pyridonate ligands. Solution reactions of simple metal salts and the sodium salts of 6-methyl-6-bromo- and 6-chloro-2-pyridone produced compounds whose nuclearities range from three to twenty four. Among these is [Co<SUB>24</SUB>(OH)<SUB>18</SUB>(OMe)<SUB>2</SUB>(Cl)<SUB>6</SUB>(mhp)<SUB>22</SUB>], the highest nuclearity complex containing cobalt, which consists of cubic-close packed planes of hydroxide, methoxide and chloride anions bridging cobalt centres. Preliminary magnetic studies indicate the presence of a high spin ground state and the possibility of superparamagnetic behaviour. Thermolysis reactions of protonated pyridones produced the first nickel and cobalt complexes which contain M<SUB>4</SUB>O<SUB>6</SUB> adamantane units. They are also the first examples of vertex- and face-sharing adamantanes. Introduction of rigid linking carboxylate ligands to the reactions of 6-methyl-2-pyridone produced a family of deca- to dodecanuclear nickel and cobalt complexes whose structures are based on centred-tricapped-trigonal prisms which contain either zero, one or two additional caps on the 'upper' and 'lower' triangular faces. The nuclearity and structure of these complexes can be controlled through variation of pyridonate, carboxylate and solvent. Similar reactions involving 6-chloro-2-pyridone produced, amongst others, a series of trimers of general formula [M<SUB>3</SUB>(O<SUB>2</SUB>CR)<SUB>2</SUB>(xhp)<SUB>4</SUB>(R'OH)<SUB>6</SUB>] and a dodecanuclear cobalt metallocycle. Replacement of binucleating with tetranucleating carboxylates led to the synthesis of two large polymetallic complexes : a cobalt tridecamer and a nickel-sodium supracage. The supracage assembly in which four nickel cubanes are linked through a sodium octahedron appears to be unprecedented. The synthetic procedures used to produce homometallic species have been expanded to give a number of bimetallic 3d-3d and 3d-4f complexes.
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Henderson, William. "Four-membered metallacyclic complexes of platinum, palladium and nickel." Thesis, University of Leicester, 1987. http://hdl.handle.net/2381/33732.
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Chapter 1 reviews the literature concerning the principal synthetic routes to metallacyclobutane, metallacyclobutan-3-one (?3-oxodimethyl-enonethane), and four-membered cyclic ylide complexes of platinum, palladium, and nickel, which contain the M-C-X-C ring system (X=C,S, or P). The preparation and characterisation of the first examples of metallathietane-3, 3-dioxide complexes of platinum, palladium, and nickel, [M{CHRS (O) 2CHR}L2], are presented in Chapter 2. The molecular structures of three of these complexes establish the presence of puckered four-membered rings, together with the presence of a hetero-allylic contribution to the bonding. Preliminary investigations into the reactivity of these metallathietane- 3, 3-dioxide complexes are detailed in Chapter 3. Ligand substitution reactions of the complex [Pt{CHPhS(O)2CHPh}(SEt2)2] afford a range of platinathietane-3,3-dioxide complexes. A study of the reactions of platinathietane-3,3-dioxide complexes with alkyl isocyanides shows that phenyl substituted complexes undergo ligand substitution, whereas benzoyl or methoxycarbonyl substituted complexes undergo a ring insertion reaction to afford the zwitterionic complexes [Pt{CH(C0R)S(O)2C(COR)C:- NHR'}(CNR')(L) ]. Chapter 4 describes the synthesis of platinathietane-3-oxide complexes, crystallographic and n.m.r. data indicating the presence of puckered and non-fluxional four-membered ring systems, with the sulphinyl oxygen in an equatorial environment. The sulphoxide and equatorial benzoyl groups of the complex [Pt{CH(COPh)S (O)CH(COPh)} (PPh3)2] co-ordinate to palladium (II) or rhodium (I) centres to afford five-membered chelate ring products. The final Chapter describes the synthesis of diphenyl-substituted oxo- dimethylenemethane (metallacyclobutan-3-one) complexes of platinum and palladium using the dianion K2[PhCHC(O)CHPh]. The molecular structure of the complex [Pt{?3-CHPhC(O)CHPh} (AsPh3)2] establishes the presence of an n3-oxodimethylenemethane ligand. The fluxional behaviour of these diphenyl oxodimethylenemethane complexes is shown to be dependent on the mode of substitution of the phenyl rings on the oxodimethylene methane ligand, with cis-diequatorial complexes being rigid in solution, and the trans-disubstituted complex trans- [Pt{?3 -CHPhC (O) CHPh} (PPh3)2] being fluxional.
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Wilson, Gleason. "Hydrogen Transfer Reaction Involving Nickel POCOP-Pincer Hydride Complexes." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1447688935.
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Wang, Ruiping. "Indenyl nickel complexes bearing alkynyl, alkenyl and triflate ligands." [Montréal] : Université de Montréal, 2003. http://wwwlib.umi.com/cr/umontreal/fullcit?pNQ82764.
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Thèse (Ph. D.)--Université de Montréal, 2003.<br>"NQ-82764." "Thèse présentée à la faculté des études supérieures en vue de l'obtention du grade de philosophiae doctor (Ph. D.) en chimie." Version électronique également disponible sur Internet.
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Jiang, Bing. "Nickel and cobalt bis (imino)pyridine complexes as catalysts for the hydrogen evolution reaction." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/667777.
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El subministrament d'energia sostenible és un desafiament crític que enfronta la humanitat. La dependència dels combustibles fòssils ha despertat l'interès en el desenvolupament de fonts d'energia lliures de carboni, entre les quals el dihidrogen que té una alta densitat d'energia seria un dels més prometedors sempre que es generi a partir d'alternatives renovables. En aquest context, dissociar l'aigua per produir hidrogen com a combustible és de gran interès i, per tant, s'estan desenvolupant una gran quantitat de catalitzadors per accelerar la velocitat d'aquesta reacció, preferiblement obtinguts a partir de metalls de transició abundants. Amb l'objectiu d'optimitzar l'economia de l'àtom de metall i facilitar l'anàlisi mecanístic, els complexos moleculars són una bona opció com a catalitzadors homogenis. En aquest tipus de compostos, els centres metal·lics que generalment es requereixen poden accedir a múltiples estats d'oxidació, de vegades a través d'intermedis de tipus metall-hidrur. No obstant això, el disseny de catalitzadors per a la reacció d'evolució de l'hidrogen (HER) inclou també una família de complexos amb lligands no innocents que poden operar com un reservori d'electrons i / o un lloc de protonació. El primer capítol d'aquesta tesi doctoral introdueix la necessitat i les tècniques per a la producció d'hidrogen per recolzar la demanda d'energia, incloent els electrocatalitzadors per HER basats en els metalls no nobles, níquel i cobalt. El segon capítol descriu els objectius d'aquesta Tesi, és a dir, la síntesi i caracterització dels lligands basats en diiminpiridina (PDI), actius en redox, juntament amb els complexos de níquel i cobalt obtingut a partir d'aquests lligands. Es presenten també com a objectius la seva avaluació electrocatalítica en HER així com la descripció dels processos des del punt de vista mecanístic. El tercer capítol presenta la preparació d'un conjunt de lligands PDI pentadentats, juntament amb la síntesi i caracterització completa de complexos de Ni(II) de hexacoordinats [Ni(Ph2PPrPDI)(Cl)](Cl) (1(Cl)) i [Ni(Ph2PPrPDI)(p)Cl)(Cl)](Cl) (2(Cl)). La ubicació dels electrons després de la reducció electroquímica d'1(Cl) es va examinar mitjançant càlculs de la teoria del funcional de la densitat (DFT) juntament amb la ressonància paramagnètica electrònica (EPR), la qual cosa va mostrar que la primera reducció d'un electró es produeix en el metall i la segona en el lligand. Es van estudiar també les propietats redox i catalítiques d'ambdós complexos. D'una banda, es va observar un potencial redox més positiu i, per tant, un sobrepotencial més baix per a 2(Cl), el que indica que la presència del substituent electroatraient Cl al lligand PDI millora l'activitat electrocatalítica. D'altra banda, 1(Cl) és més actiu per al HER en termes de TOF i constant de velocitat. Els estudis d'estabilitat a curt termini per a 1(Cl) i 2(Cl) en condicions de HER per CV indiquen que la catàlisi és homogènia sense descomposició, mentre que l'estabilitat a llarg termini analitzada per electròlisi potencial controlada mostra la generació d'una nova espècie transitòria que pot desencadenar la reacció d'oxidació d'hidrogen i al seu torn reduir el sobrepotencial per a la HER. El quart capítol s'enfoca en la síntesi i caracterització de complexos de Co coordinats de cinc amb els lligands aplicats en el tercer capítol ([CoI(Ph2PPrPDI](BF4), 3(BF4) i [CoI(Ph2PPrPDI(p)Cl](BF4), 4(BF4)). Les dades de l'electroquímica mostren que aquests complexos són actius per a la HER en medi orgànic, passant després de la reacció amb protons per espècies d'hidrur de Co(III) que es van identificar mitjançant espectroscòpia UV-vis i RMN. Sobre la base de l'espectroscòpia RMN, el compost de Co(I) inicial es va recuperar després d'un cicle de reacció catalític, el que demostra un mecanisme homolític per HER. Finalment, el cinquè capítol enumera les conclusions més rellevants extretes del treball realitzat.<br>Sustainable energy supply is a critical challenge humanity is facing. The dependence of fossil fuels have ignited interest in the development of carbon-free energy sources, among which energy-dense dihydrogen would be one of the most promising when generated from renewable alternatives. In this context, splitting water to produce hydrogen as fuel is of great interest, and hence a large number of catalysts made from earth-abundant transition metals have been developed to accelerate the reaction rate. For the purpose of effectively using metal-atom economy and facilitating mechanistic analysis, molecular complexes as homogenous catalysts got much attention. In this kind of compounds, metal centres are usually required to accommodate multiple redox states and experience metal-hydride intermediates. However, there has been a renaissance in catalysts’ design for the hydrogen evolution reaction (HER) by coordinating the metal centre with non-innocent ligands who can operate as an electron reservoir or/and protonation site. The first Chapter of this PhD Thesis generally introduce the need and techniques for hydrogen production to support the energy demand, reviewing electrocatalysts for the HER based on the non-noble metals nickel and cobalt. The second Chapter describes the objectives of this Thesis, i.e., the synthesis and characterization of redox-active pyridine diimine (PDI)-based ligands and the corresponding nickel and cobalt complexes. Their electrocatalytic evaluation in HER is aimed, as well as the description of the processes from the mechanistic point of view. The third Chapter presents the preparation of a set of pentadentate PDI ligands, synthesis and full characterization of six-coordinated Ni(II) complexes [Ni(Ph2PPrPDI)(Cl)](Cl) (1(Cl)) and [Ni(Ph2PPrPDI(p)Cl)(Cl)](Cl) (2(Cl)) using techniques including mass spectroscopy, UV-vis spectroscopy, X-ray crystallography and elemental (C, H, N) analysis. The electron location upon electrochemical reduction of 1(Cl) was examined by density functional theory (DFT) calculations along with electron paramagnetic resonance (EPR), revealing the metal-based nature for the first one-electron reduction and ligand-based for the second one. The redox and catalytic properties of both complexes were studied. On the one hand, more positive redox potential and therefore lower overpotential were observed for 2(Cl), indicating that the presence of the electron-withdrawing Cl substituent in the PDI ligand scaffold improves the electrocatalytic activity. On the other hand, 1(Cl) is more active for the HER in terms of turnover frequency and rate constant. Short-term stability studies for 1(Cl) and 2(Cl) in the course of HER by CV indicates homogenous catalysis without decomposition, whereas long-term stability analysed by controlled potential electrolysis shows the generation of a new transitory species which can trigger the hydrogen oxidation reaction and reduce the overpotential for the HER. The fourth Chapter focus on the synthesis and characterization of five-coordinated Co complexes bearing the ligands applied in the third Chapter ([CoI(Ph2PPrPDI](BF4), 3(BF4) and [CoI(Ph2PPrPDI(p)Cl](BF4), 4(BF4)). Electrochemistry data shows that these complexes are active for the HER in organic media, undergoing protonation to form Co(III) hydride species which were identified by UV-vis and NMR spectroscopy. On the basis of NMR spectroscopy, the initial Co(I) compound was recovered after a catalytic reaction cycle, demonstrating a homolytic mechanism for HER by this system. Finally, the fifth Chapter lists the most relevant conclusions extracted from the work carried out.
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Heydenrych, Greta. "A DFT study of the catalytic hydrocyanation of ethylene with nickel complexes." Thesis, Stellenbosch : Stellenbosch University, 2005. http://hdl.handle.net/10019.1/21456.
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Dissertation (PhD)--University of Stellenbosch, 2005.<br>ENGLISH ABSTRACT: DFT calculations employing the B3LYP functional were done to investigate the mechanism for the Ni-catalyzed hydrocyanation of ethylene as proposed by Tolman. Although this reaction is an important industrial process, its mechanism has never been studied computationally, apart from calculations pertaining to ligand tailoring.
This study comprises a detailed configurational analysis of each step of the reaction cycle, charge decomposition analysis of pertinent species and analysis of the activation barriers involved at each step. A model ligand, PH3, is employed, due to its electronic similarity to the experimental ligand most widely used, P(O-o-tolyl)3, and its small size, which makes it amenable for calculations at this level.
It was found that oxidative addition of HCN to the precursor complex (ethylene)NiL2 (L=PH3) can take place in one step and that it is the rate-determining step in the gas phase. The resulting adduct has H+ (which becomes a hydride) and CN- coordinated in the cis configuration. Ligand dissociation yields three configurations of (ethylene)-NiHCNL, of which only two can participate in the catalytic cycle. It is shown that this is because migration-insertion of ethylene into the Ni-H bond takes place before, or concomitant with, association of a second ethylene molecule, contrary to expectation. This path therefore requires that ethylene and hydrogen are coordinated in the cis configuration, something only possible for two of the three isomers of (ethylene)NiHCNL. The calculations support the mechanism of associative reductive elimination and shows that elimination can only take place if the ethyl and cyanide groups are in the cis configuration.
Analysis of the energetic profile of the reaction shows that entropy effects play a very important role in the propagation of the cycle, at least in the gas phase.
Preliminary work on the effect of Lewis acids the catalytic cycle is presented, with structural and energetic analysis.
An important general conclusion is that the standard way of representing the energy profile of reactions where intermolecular transitions (as opposed to intramolecular transitions only) take place can be misleading. It will be argued that the implicit assumption that two species which are minimum energy structures on distinct potential energy surfaces will also be an energy minimum on one potential energy surface skews the energy profile of the reaction. The consequence of this is that care must be taken in representing energy profiles for reactions where more than one distinct species participates.<br>AFRIKAANSE OPSOMMING: Die meganisme, soos deur Tolman voorgestel, van die Ni-gekataliseerde hidrosianering van etileen word ondersoek met behulp van Kohn-Sham elektrondigtheidsteorie (density finctional theory, DFT) berekeninge waarin die B3LYP-funksionaal gebruik word. Alhoewel die reaksie ‘n belangrike proses is in die industrie, is die volle me-ganisme nog nooit met behulp van berekeninge bestudeer nie. Daar is egter wel al werk gedoen aangaande sekere aspekte van die reaksie, byvoorbeeld ligandontwerp.
Hierdie studie behels ‘n noukeurige konfigurasionele analise van elke stap van die reaksie-siklus, ladingsverdelingsanalise (charge decomposition analysis, CDA) van sekere belangrike spesies asook die analise van die energiestappe betrokke by elke stap. Fosfien is gekies as ‘n modelligand, omdat dit elektronies ooreenstem met P(O-o-toliel)3, die ligand wat meestal in eksperimentele werk gebruik is. Die klein grootte van fosfien maak dit ook geskik vir be-rekeninge op hierdie vlak.
Daar is bevind dat die oksidatiewe addisie van HCN aan die voorgangerkompleks (etileen)-NiL2 (L=PH3) in een stap kan plaasvind en in die gasfase snelheidsbepalend is. Die adduk (ettileen)NiHCNL2 bevat H+ (wat ‘n hidried word) en CN- in die cis-posisie relatief tot mekaar. Liganddissosiasie lewer drie isomere van (etileen)NiHCNL. Daar is bevind dat slegs twee van dié isomere aan die katalitiese reaksie kan deelneem, omdat die migrasie-inplasing (migration-insertion) van etileen in die Ni-H-binding voor, of saam met, die assosiasie van ‘n tweede etileen-molekule plaasvind. Dit is slegs moontlik indien waterstof en etileen cis teenoor mekaar is, wat geld vir twee van die isomere. Die meganisme van assosiatiewe reduktiewe eliminasie word deur die berekeninge gerugsteun. Voorts blyk dit vanuit die berekeninge dat die etiel- en sianiedgroepe cis teenoor mekaar moet wees voordat reduktiewe eliminasie van propionitriel kan plaasvind.
Analise van die energetiese profiel van die reaksie toon dat entropie-effekte ‘n belangrike rol speel in die voortsetting van die reaksie in die gasfase.
Die invloed van Lewissure op die katalitiese siklus word, met behulp van strukturele en energetiese analise bespreek.
‘n Belangrike algemene gevolgtrekking is dat die standaardvoorstelling van die energetiese profiel van reaksies waarin intermolekulêre oorgange (teenoor slegs intramolekulêre oorgange) voorkom, misleidend kan wees. Dit word gestel dat die implisiete aanname dat twee spesies wat minumum-energiestrukture verteenwoordig op twee verskillende potensiële energie-oppervlaktes ook ‘n minimum-energiestruktuur voorstel op een potensiële energie-oppervlakte, die energieprofiel skeeftrek. Gevolgtrekkings vanuit hierdie energieprofiele van reaksies waar meer as een onderskeibare spesie deelneem, moet dus met omsigtigheid gemaak word.
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Speiser, Fredy. "Oligomerisation of ethylene with Ni-complexes." Université Louis Pasteur (Strasbourg) (1971-2008), 2002. http://www.theses.fr/2002STR13221.
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Au cours de ce travail de thèse des nouvelles familles de ligands P-N, N-O bidentates et P-N tridentates ont étés préparés pour les utiliser en synthèse de complexes de Ni et Fe. Ces ligands possèdent un hétérocycle azoté à cinq ou six chaînons qui peut porter un groupement stériquement encombré et une fonctionnalité phosphorée dont la basicité peut être variée. La synthèse des complexes de Ni est réalisée dans des conditions très douces en faisant réagir des quantités équimolaires de ligand avec [NiCl2(DME)]. Les complexes préparés sont paramagnétiques de sorte qu'un grand nombre d'entre eux à dû être caractérisé par diffraction de rayons X. Leurs moments magnétiques en solution on été déterminés à l'aide de la méthode d'Evans. Les propriétés catalytiques des précatalyseurs de Ni mis au point se rapprochent à un système de dimérisation de l'éthylène, de sorte que le [NiCl2(PCy3)2], un catalyseur de dimérisation typique, a été choisi comme référence. On obtient une fréquence de rotation de 25108 mol C2H4 / mol Ni·h-1 avec une sélectivité de 75% pour les C4 (10% a-oléfine). Au-dessous de 6 équivalents d'AlEtCl2, le [NiCl2(PCy3)2] est inactif. Pour tous les complexes synthétisés, pendant ce travail, on observe des fréquences de rotation de 40000 à 174330 mol C2H4 / mol Ni·h-1 et des sélectivités pour les C4 de 65 à 92% (8 à 60% a-oléfine). La plupart des complexes de Ni préparés montrent de bonnes activités en présence de seulement 1,3 ou 2 équivalents d'AlEtCl2. Avec des cocatalyseurs non-halogénes, comme p. Ex. Le MAO, des sélectivités pour les a-oléfines de 60% peuvent être obtenues<br>New families of bidentate P-N, N-O and tridentate P-N ligands were prepared and used in the synthesis of nickel and iron complexes. These ligands posses a five or six membered heterocycle which carries a sterically demanding substituent and a phosphorous moiety whose basicity can be varied. The synthesis of the complexes was realised under very mild conditions by reacting equimolar quantities of the ligand and [NiCl2(DME)]. All complexes were paramagnetic and therefore had to be characterised by X-ray diffraction. Their magnetic moments in solution were determined with the help of the Evan's method. [NiCl2(PCy3)2] a typical dimerisation catalyst, was chosen as reference as the catalytic properties of the prepared complexes were comparable to those of a typical dimerisation system. For the reference complex turnover frequencies of 25108 mol / C2H4 / mol Ni·h-1 with a selectivity of 75% for butenes (10 % a-olefin) were observed. Below 6 equivalents of AlEtCl2 [NiCl2(PCy3)2] was inactive. For all complexes which were synthesised turnover frequencies between 40000 and 174330 mol / C2H4 / mol Ni·h-1 and selectivities for C4 oligomers of 65 to 92% (8 to 60% a-olefin) were obtained. Most of the synthesised complexes show good activities in the presence of only 1,3 or 2 equivalents of AlEtCl2. When non-halogenated cocatalysts as e. G. MAO were applied a-olefin selectivities of 60% were obtained
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Hawkins, I. M. "New transition metal complexes containing phosphine and sulphur ligands." Thesis, University of East Anglia, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235225.
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Perry, Richard John. "Structural studies on high oxidation state nickel complexes and their nickel(II) precursors using EXAFS spectroscopy." Thesis, University of Southampton, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358484.
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Barker, James. "Studies of amidines and their complexes with the nickel elements." Thesis, Durham University, 1985. http://etheses.dur.ac.uk/7591/.
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Amidines [RNC(R')NR, I] and their complexes of the nickel group metals have been studied. Accurate mass spectrometry applied to (R'=H, R=Ph; R'=CH(_3), R=Ph; R'=Ph=R) have given detailed fragmentation patterns which form the basis for the interpretation of related amidines. Differences in skeletal fragmentation patterns were noted between formamidines and acetamidines/benzamidines, (^1)H, (^13)C and (^19)F n.m.r. and mass spectroscopy of lithioamidines indicate a bidentate symmetrically bonded amidine. The reactions of amidines [RN(X)C(R^)NR] X=H, Li) with compounds of the nickel group metals, results in a wide variety of complexes; their nature depending on the amidine substituents, the metal and the synthetic route used. Complexes with N,N'chelate, or't/20-metallated, and bridging groups were prepared and characterised together with complexes containing new N,N'chelate and bridging groups, resulting from nucleophilic attack of an amidine at a coordinated nitrile. The reactions of M(PhCN)(_2)C1(_2) (M=Pd, Pt) and anhydrous NiC1(_2) with lithioamidines result in yellow Pt(Am)(_2), where Am = RNC(R')NR, red Pd(_2)(Am)(_4) and dark green Ni(_2)(Am)(_4) complexes. The platinum complexes are monomeric for the acetamidine (R'=CH(_3)), and benzamidine (R(_6)H(_5)) ligands, though for palladium the benzamidine complexes are dimeric. The nickel complexes are dimeric for the acetamidine,and benzamidine ligands. Spectroscopic studies indicate that the amidino-groups adopt a carboxylate type mode of bonding through the two nitrogen atoms, and the structure of one of the complexes, bis, N,N'diphenylbenzamicline-platinum(II) has been characterised by X-ray crystallography. The structure showed a monomeric PtN(_4) square planar unit. N.m.r. ((^19)F and (^13)C) studies have indicated fluxionality when M=Pd, R'=C(_6)H(_5), R=C(_6)H(_4)-F-p. With K(_2)MCl(_4)(M=Pd, Pt) and NiC1(_2), N,N'diarylamidines form polymeric ortho-metallated complexes, N,N' diarylformamidines and acetamidines form six-membered rings, benzamidines five-membered. Treatment of Pt(PhCN)(_2)C1(_2) with HN(Li)(C(_6)H(_5))NH results in nucleophilic attack at the nitrile and formation of Pt[HNC(C(_6)H(_5))NC(C(_6)H(_5))NH](_2). A similar reaction occurred with Pd(PhCN)(_2)C1(_2) and HNLiC(C(_4)(_9))NH.
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Branscombe, Neil D. J. "Studies on binuclear compartmental Schiff-base thiolate complexes." Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299550.
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Garrido, Barros Pablo. "Molecular Water Oxidation Catalysts Based on Copper and Nickel Complexes." Doctoral thesis, Universitat Rovira i Virgili, 2018. http://hdl.handle.net/10803/665124.
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Aquesta Tesi Doctoral es centra en l’estudi de catalitzadors moleculars per a l’oxidació d’aigua basats en coure i níquel, ja que la seva gran abundància i baix cost els fa potencials candidats pel seu ús en sistemes catalítics. Tot i així, avui en dia hi ha una important mancança d’informació respecte als seus mecanismes de reacció i els factors que influeixen la seva activitat.
Per això, en primer lloc, es desenvolupen nous catalitzadors moleculars basats en el coure com a centre metàl·lic. L’estudi mecanístic d’aquests catalitzadors revela l’important rol que té l’oxidació del lligand en el cicle catalític a l’hora de controlar el sobre-potencial de la reacció. Al mateix temps, en col·laboració amb el grup del Professor Maseras (ICIQ) es descobreix un nou mecanisme per a la formació de l’enllaç oxigen-oxigen que opera en diferents tipus catalitzadors de coure. Aquest nou mecanisme sense precedents permet redefinir l’escenari mecanístic per a l’oxidació d’aigua.
Posteriorment, es realitza el disseny de nous lligands amb diferents propietats redox que permeten estudiar factors que influeixen en l’activitat i el mecanisme de reacció. Això proporciona informació rellevant per al disseny de nous catalitzadors més actius, estables i eficients.
També s’aborda la immobilització dels catalitzadors desenvolupats sobre els elèctrodes basats en grafè. D’aquesta manera es descobreix el paper essencial que té la deslocalització d’electrons en els orbitals π, que permet incrementar la cinètica de la reacció per més de dues ordres de magnitud.
Finalment, el coneixement generat en coure s’intenta expandir per a la seva aplicació en els catalitzadors de níquel. Això permet estudiar el caràcter làbil dels complexos de níquel en medis bàsics, que determina la presència de dos mecanismes d’operació basats en espècies moleculars i òxids de níquel respectivament.<br>Esta Tesis Doctoral se centra en el estudio de catalizadores moleculares para la oxidación de agua basados en cobre y níquel, ya que su gran abundancia y su bajo coste los hace potenciales candidatos para su uso en sistemas catalíticos. A pesar de esto, hoy en día hay una importante carencia de información con respecto a sus mecanismos de reacción y los factores que determinan su actividad.
Por ello, en primer lugar, se desarrollan nuevos catalizadores moleculares basados en cobre como centro metálico. El estudio mecanístico de dichos catalizadores revela el importante rol que tiene la oxidación del ligando en el ciclo catalítico a la hora de controlar el sobre-potencial de la reacción. Al mismo tiempo, en colaboración con el grupo del Profesor Maseras (ICIQ) se descubre un nuevo mecanismo para la formación del enlace oxígeno-oxígeno que opera en diferentes tipos de catalizadores de cobre. Este nuevo mecanismo sin precedentes permite redefinir el escenario mecanístico para la oxidación de agua.
Posteriormente, se realiza el diseño de nuevos ligandos con diferentes propiedades redox que permiten estudiar los factores que influyen en la actividad y el mecanismo de reacción. Esto proporciona información relevante para el diseño de nuevos catalizadores más activos, estables y eficientes.
También se aborda la inmovilización de los catalizadores desarrollados sobre electrodos basados en grafeno. De esta forma se descubre el papel esencial que tiene la deslocalización de electrones en orbitales π, que permite incrementar la cinética de reacción por más de dos órdenes de magnitud.
Finalmente, el conocimiento generado en cobre se intenta expandir para su aplicación en catalizadores de níquel. Esto permite estudiar el carácter lábil de los complejos de níquel en medios básicos, que determina la presencia de dos mecanismos de operación basados en especies moleculares y óxidos de níquel respectivamente.<br>This Doctoral Thesis focuses on the study of molecular catalysts for water oxidation based on copper and nickel since their high abundance and inexpensive character make them potential candidates for their use in catalytic systems. Despite that, there is a current lack of information regarding their reaction mechanism and the factors that determine their activity.
Therefore, we first develop new molecular catalysts based on copper as metal center. Their mechanistic study reveals the essential role that the ligand oxidation has in the catalytic cycle as tool to control the reaction overpotential. In collaboration with Prof. Maseras group (ICIQ) a new mechanism for the oxygen-oxygen bond formation is found to operate in different copper catalysts. This unprecedented mechanism allows us to redefine the mechanistic scenario in water oxidation.
Later on, the design of new ligands with different redox properties is addressed. That allows to study the factors that have influence on the activity and reaction mechanism and provide valuable information for the design of more active, stable and efficient new catalysts.
Moreover, the immobilization of the molecular catalyst on the surface of graphene-based electrodes is also studied. We discover the essential role of the π-delocalization in increasing the reaction kinetic by more than two orders of magnitude.
Finally, the knowledge developed with copper complexes is applied in nickel catalysis. This allows to study the labile character of nickel complexes in basic media that determine the presence of two different operating mechanism based on molecular species and nickel oxides respectively.
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Le, Page Matthew Derek. "The synthesis, characterization, and reactivity of nickel 2-pyridylphosphine complexes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0018/NQ56574.pdf.
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Van, Wyk Shane Cedrick. "Some new bimetallic nickel and palladium complexes for catalysis applications." University of the Western Cape, 2015. http://hdl.handle.net/11394/4873.
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>Magister Scientiae - MSc<br>This thesis reports on the syntheses of new bimetallic iminopyridyl nickel(II) and
palladium(II) complexes as catalyst precursors for ethylene ligomerization/polymerization. Tetrahydrophenyl-linked iminopyridyl ligands, pyridin-2-ylmethyl-{4-[(pyridin-2-ylmethylimino)-methyl]-benzylidene}-amine (L1) and (2-pyridin-2-yl-ethyl)-{4-[(2-pyridin-2-yl-ethylimino)-methyl]-benzylidene}-amine (L2) were prepared via condensation from terephthaldehyde and 2 molar equivalents of a primary pyridylamine. Alkyl-linked iminopyridyl ligands N,N'-bis-pyridin-2-ylmethylene-propane-1,3-diamine (L3), N,N'-bispyridin-
2-ylmethylene-butane-1,4-diamine (L4) and N,N'-bis-pyridin-2-ylmethylenepentane-
1,5-diamine (L5) were prepared by condensation of 2 equivalents of 2-
pyridinecarboxaldehyde and a primary diamine. The ligands were obtained as either red oils or orange solids. These ligands were characterized using Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), mass spectrometry (MS), elemental analysis (EA), ultraviolet-visible spectrophotometry (UV-Vis) and thermal gravimetric analysis (TGA) where applicable. The tetrahydrophenyl-linked iminopyridyl ligands were subsequently used to prepare their corresponding homobimetallic palladium(II) and nickel(II) complexes. A 1:2 reaction of the ligands with PdCl2(COD), NiCl2(DME) and NiBr2(DME) gave palladium(II) and nickel(II) complexes C1-C6 in moderate to very good yields (58-94%). The palladium(II) complexes were found to be stable, but light-sensitive solids while the nickel(II) complexes were found to be stable, but light and air sensitive solids. These complexes were characterized using FTIR, NMR, EA, MS, UV-Vis and TGA. These complexes were then tested for catalytic activity of ethylene oligomerization. It was found that complexes C1 and C5 were highly active when activated by the cocatalysts methylaluminoxane (MAO) as well as ethyl aluminium dichloride (EADC). It was found that EADC gave the highest activity so the remaining catalysts (C3 and C6) were tested exclusively with EADC. All four complexes were active for ethylene oligomerization with yields of between 2.7-6.5 g, with C5 providing the highest activity and C1 the lowest. These catalysts were highly selective towards C4 oligomers with percentages ranging from 71-81%.
Optimization studies were then carried out with C3 by varying the pressure and Al:Ni ratio.
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Adhikary, Anubendu. "Synthesis and Catalytic Applications of Nickel and Palladium Pincer Complexes." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439281406.
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Wang, Ding. "Redox reactivity of original nickel complexes combined with divalent lanthanides." Thesis, Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAX100.
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Le but de ce travail a été de concevoir des structures hétérobimétalliques originales combinant une espèce réactive de nickel et un fragment organolanthanide divalent en présence d'un ligand central rédox non-innocent. Au sein de celles-ci, d’une part, le fragment lanthanide divalent joue le rôle crucial de réducteur mono-électronique. D’autre part, les propriétés de non-innocence rédox du ligand permettent de transférer une partie de la densité électronique vers le second centre métallique, et ainsi de moduler sélectivement la réactivité du métal de transition. Dans ce contexte, l'activation du monoxyde de carbone a été étudiée en utilisant un complexe hétérobimétallique particulier, dont les deux centres métalliques sont liés à l’aide d’un ligand 2,2'-bipyridimine pontant. Dans son état fondamental, ce complexe présente un comportement multiconfigurationnel. Une étude cinétique minutieuse a d’ailleurs montré que cette configuration électronique particulière était responsable de la stabilisation des espèces acyles intermédiaires. Des variations de la structure des complexes hétérobimétalliques ont été progressivement effectuées afin d'explorer l’influence des configurations électroniques spécifiques, induites par les fragments de lanthanides divalents, sur la réactivité des complexes. Tout d’abord, diverses espèces de trifluorométhyle de nickel ont été étudiées, permettant une activation de la liaison C–F facilitée par la présence de l'ion lanthanide. Par la suite, cette réactivité a pu être appliquée à l’étude de complexes métalliques de type difluorocarbènes. Par ailleurs, l’utilisation d’un ligand rédox non-innocent, cette fois dissymétrique, a permis de dévoiler une réaction de couplage radicalaire entre deux ligands, induite par la présence du fragment lanthanide réducteur. En particulier, une transformation inhabituelle entre une forme dimère et trimère a été observée. Le couplage entre deux unités de complexe de nickel a ensuite été réalisé par réduction avec du potassium-graphite. Dans ce composé couplé, une modulation de la densité de spin au niveau du système rédox-actif est induite par le fragment lanthanide divalent. Enfin, des travaux préliminaires à partir d’un ligand tridenté ont été entrepris de façon à étudier des complexes de nickel rédox-actifs possédant des états d'oxydation peu communs, et laissant entrevoir une réactivité intéressante impliquant des processus radicalaires<br>This work aimed at designing an original heterobimetallic framework combining a reactive nickel species and a divalent organolanthanide fragment in the presence of a redox non-innocent ligand. The crucial role of the divalent lanthanide moiety is to act as a single-electron transfer reductant. As redox non-innocent ligands are able to allow strong electron correlation, the reactivity of the reactive transition metal center can be selectively modulated. In this context, carbon monoxide activation was investigated using a special heterobimetallic complex bridged by a 2,2’-bipyridimine ligand. A multiconfigurational ground state behavior was observed and found responsible for the stabilization of the intermediate acyl species, as evidenced by kinetic analysis. Structural modifications on the heterobimetallics were progressively performed in order to explore the influence of the specific electronic configurations, induced by the divalent lanthanide fragments, on the reactivity of the complexes. Trifluoromethyl nickel species were first studied, yielding a facile C-F bond activation triggered by the lanthanide ion, and such reactivity could be further applied to study difluorocarbene metal complexes. A dissymmetric, redox-active ligand was used afterwards, resulting in a radical coupling transformation between two ligands in the presence of the reductive lanthanide fragment. An intriguing dimer-trimer transition was especially observed. The coupled nickel species was isolated by reduction with potassium graphite and revealed a modulation of the spin density on the redox-active system induced by the divalent lanthanide fragment. Finally, a tridentate ligand scaffold was investigated in an attempt to study redox-active nickel complexes with uncommon oxidation states, which led to interesting reactivity insights involving radical processes
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Alshmimri, Sultan. "The behaviour of β-triketimine nickel complexes in ethylene polymerization". Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/the-behaviour-of-triketimine-nickel-complexes-in-ethylene-polymerization(3374d8ea-3d60-46ea-a51a-6a6b5239a1c2).html.
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Seven β-triketimine nickel complexes C1-C7 with composition [L1-7Ni(μ-Br)2NiL1- 7][BArF4]2, where L1 = HC{C(Me)=N(2,4,6-Me3C6H2)}3, L2 = HC{C(Me)=N(2,6- Me2C6H3)}3, L3 = HC{C(Me)=N(2,4-Me2C6H3)}3, L4 = HC{C(Me)=N(2-MeC6H4)}3, L5 = HC{C(Me)=N(2,4,6-Me3C6H2)}2{C(Me)=N(2,6-Me2C6H3)}, L6 = HC{C(Me)=N(2,4,6-Me3C6H2)}{C(Me)=N(2,6-Me2C6H3)}2, and L7 = HC{C(Me)=N(2,4,6-Me3C6H2)}{C(Me)=N(2,6-iPr2C6H3)}2 were synthesized from the interaction of nickel(II) bromide with L1-7 in the presence of NaBArF (BArF = [(3,5- (CF3)2C6H3)4B]−). These complexes were then fully characterized by single-crystal X- ray diffraction (XRD), MALDI-MS and elemental analysis. From XRD results, they were found to be five-coordinated dimeric bromide-bridged species [LNi(μ- Br)2NiL][BArF]2. The geometry at nickel was distorted square pyramidal, with the τ parameter in the range 0.05 to 0.28. In addition, an enamine-diimine nickel complex C8: (L2-NiBr2) was synthesized from triketimine ligand L2 and nickel dibromide in THF, thus lacking the weakly co-ordinating BArF anion. This complex was found to be pseudotetrahedral, where only two of the three imine nitrogen atoms co-ordinated. These two nitrogen atoms and two bromine atoms formed the coordination shell of Ni(II). The six-membered ring [Co-N1-C2-C3-C4-N2] adopted a boat conformation. These complexes (C1-C7) were screened in the polymerization of ethylene monomer using methylaluminoxane (MAO) as cocatalyst in toluene as solvent at 30°C. It was observed that the steric and electronic variations conferred on the complexes by ligands L1-7 had a strong influence on the activity and also on the properties of the produced polyethylene. The catalytic activity decreased in the order C2 > C1 > C6 > C5 > C7 in the range 3229 to 271 kg PE (mol Ni)-1 h-1 for a standard set of conditions (3 bar ethylene, 30 ̊C, Al:Ni 2000), while the catalysts C3 and C4, bearing only a single ortho substituents, were inactive under identical conditions. Those conditions also had strong influences on catalyst activity and polymer properties: Al:Ni ratio in the range 500 to 3000 maximized activity at 2000. For the polymerization temperature in the range 20 to 50 °C, the activity was maximized at 30 °C, while the number of branches increased with temperature while Mn decreased due to increased chain transfer. Increasing the polymerization pressure resulted in fewer branches while the molecular weight increased because of high concentration of ethylene monomer. The effect of the nature of the counterion on polymerization activity and on the polymer properties was investigated when ethylene was polymerized by C8 (N,N-Ni) and C2 (N,N,N-Ni). It was found that polyethylene produced by C8 had significantly greater crystallinity (Tm 59 ̊C, 35 branches per 1000 carbons) than that produced by C2 (Tm 36 ̊C, 53 branches per 1000 carbons). The presence of the weakly nucleophilic counterion (BArF) as in C2, may have facilitated chain walking, resulting in a branched polymer, whereas [MeMAO]- (C8) was a slightly more nucleophilic counterion impeding chain walking. Furthermore, activity was also much greater for C2 than for C8. This is the first report of an anion effect on branching.
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Thangavadivale, Vargini. "The application of nickel complexes to halogen bonding and hydrofluoroarylation." Thesis, University of York, 2015. http://etheses.whiterose.ac.uk/10781/.
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The N-heterocyclic carbene complex, (1,5-hexadiene)Ni(IPr) (IPr = 1,3-bis(2,6-diisopropylphenyl)-4,5-dihydro-2H-imidazol-2-ylidene) was found to catalyse the hydrofluoroarylation reaction of alkynes at lower temperatures and more cleanly compared to the Ni(PR3)2 (R =Cyp and Cy) catalysts reported in the literature. Kinetic studies of the hydrofluoroarylation reaction using the above catalyst was carried out to obtain more information of the mechanism, which is addressed in chapters 2 and 3. The reaction followed in-situ by 1H-NMR spectroscopy using 4,4-dimethylpentyne and C6F5H as the substrates catalysed by (1,5-hexadiene)Ni(IPr), suggested saturation kinetics with respect to the alkyne and first order dependence on the fluoroarene and the catalyst. The results also suggests an initial coordination of the alkyne to nickel Ni(IPr)(alkyne), the active species that reacts with the fluoroarene. The mechanistic understanding gained from this study, is similar to that proposed in the literature based on the DFT calculations using Ni-PR3 as the catalyst. Chapter 4 details the synthesis and study of two series of self-complementary nickel complexes Ni(X)(PEt3)2(y-C6F4I) (X=F-, Cl-, Br- and I- and y = ortho and para) exhibiting intermolecular halogen bonding interactions. X-ray crystallographic studies revealed the strength of the halogen bonding interaction decreases in the following order, with different XB acceptors; F->Cl-≈Br->I-. The XB interaction occurs at an angle of 180° for Ni-F…I and ranges from 139° to 147° for Ni-X…I, where X=Cl, Br and I). When PEt3 ligand were substituted with PEt2Ph ligand the halogen bonding interaction was observed to weaken. The higher number of fluorines ortho to the halogen bond donor strengthened the interaction. Investigation of the Ni-F…I interactions by solid state NMR spectroscopy upon the 19F nuclei showed a downfield shift in the fluoride resonance when compared to its analogous complex without the halogen bonding interaction. The thermodynamic study of the halogen and hydrogen bonding interactions of nickel fluoride complexes, ligated to N-heterocyclic carbene ligands are reported in chapter 5. Interactions of indole and C6F5I have been studied with Ni(F)(i-Pr2Im)2(C6F5) using 19F-NMR spectroscopic titrations (For C6F5I, K300 =7.2; change in S° =-50.2±1.2 J/(mol.K); change in H° =-23.9±0.3 kJ/mol and for indole K300 =33; change in S°= 53.6±1.7 J/ (mol.K); change in H° =-32.7±0.5 kJ/mol).
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Nambukara, Wellala Nadeesha P. "Synthesis and Catalytic Activities of Nickel Complexes Bearing Flexible Tridentate Ligands." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1491561548324255.
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Townsend, James Alan. "Synthesis, characterization and application of N-substituted and C-substituted nickel cyclam cataylsts in hydrodehalogenation reactions." Diss., Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/1469.
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Sivade, Alain. "EVALUATION DE PHOSPHINO-TRIS(m-METAPHENYLSULFONATES) EN CATALYSE D'OLIGOMERISATION ET DE TELOMERISATION AU CONTACT DE COMPLEXES DU NICKEL OU DU PALLADIUM." Toulouse 3, 1987. http://www.theses.fr/1987TOU30221.
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Zimmerman, Joshua R. "Model complexes for nickel containing enzymes: Carbon monoxide dehydrogenase/ acetyl coenzyme a synthase and nickel superoxide dismutase." Diss., Wichita State University, 2009. http://hdl.handle.net/10057/2555.
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Carbon Monoxide Dehydrogenase / Acetyl CoA Synthase (CODH/ACS) is a bifunctional enzyme that catalyzes the reduction of CO₂ to CO and the assembly of Acetyl CoA. The A-cluster active site, which catalyzes the Acetyl CoA synthesis, contains a Fe-S cubane bridged by a cysteine thiolate to a dinuclear Ni(µ-S)₂Ni cluster (Fig. 1). The proximal nickel, Nip, has S₃X coordination, while the distal nickel, Nid, has N₂S₂ coordination. This project focuses on the synthesis of model complexes for the asymmetric dinuclear metal center in order to understand the electronic characteristics of this cluster and investigate the feasibility of proposed intermediates. The initial target compound is shown in Figure 2. We have developed an efficient method for synthesizing metal complexes with mixed N/S coordination through the use of 2-2'-dithiodibenzaldehyde, DTDB. Symmetric nickel complexes with NS₃ coordination have previously been synthesized using DTDB and various bidentate NS ligands. Herein we present our results upon incorporating N,N-dimethylethylenediamine into this methodology.<br>Thesis (Ph.D.)--Wichita State University, College of Liberal Arts and Sciences, Dept. of Chemistry
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Sampson, Claire Louise. "Construction of dinuclear complexes using multidentate ligands." Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311744.
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Digua, Abdelouafi. "Electrosynthèse de poly(paraphenylène) en poudre et en films catalysée par des complexes du nickel." Paris 13, 1986. http://www.theses.fr/1986PA132012.
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Réduction électrochimique catalytique de dérivés aryles dihalogènes en presence de catalyseurs à base de nickel(0). Structure regulière; la masse moléculaire moyenne est de l'ordre des plus hauts polyparaphenylenes prépares jusqu'à présent. Réduction ou oxydation réversibles avec changement de couleur
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Dougherty, William G. Jr. "Synthesis, structure and reactivity of nickel-nickel complexes for understanding the A cluster in acetyl coenzyme A synthase." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 167 p, 2007. http://proquest.umi.com/pqdweb?did=1464120791&sid=6&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Ruan, Zhixiong. "C−H Alkylations and Alkynylations Using Ruthenium, Nickel and Manganese Complexes." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2017. http://hdl.handle.net/11858/00-1735-0000-0023-3F33-6.
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Piga, Francesco. "Magnetostructural correlations in iron(II)- and nickel(II)-based cluster complexes." Thesis, University of Nottingham, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604299.
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This thesis presents a study of the magnetic properties of cluster complexes of nickel and iron, with a focus on the relationships between structure and magnetism. Chapter 1 gives an introduction to the concepts involved in molecular magnetism, with particular attention to single-molecule magnets (SMMs). The main types of SMMs are outlined, and the origin of magnetic anisotropy and its role in the single-molecule magnetism phenomena are discussed, as well as the potential applications of SMMs as data storage devices. The chapter also describes the experimental techniques employed for the characterisation of the complexes studied. Chapter 2 deals with three Ni(II)-based, cubane-like complexes with formula [Ni(hmp)(MeOH)CI]4 (complex 1), [Ni(hmp)(dmb)CI]4 (2) and [Ni(hmp)(dmp)Clh (3), where hmp- is the anion of 2- (hydroxymethyl)pyridine, dmb is 3,3-dimethylbutan-l -01 and dmp is 2,2-dimethylpropan-l -ol. A magnetostructural study was carried out on these complexes, employing X-ray crystallography, SQUID magnetometry, FDMRS and MCD spectroscopy.l MCD spectra allowed for determining the signs of superexchange interactions and magnetic anisotropy parameters, and simulations on FDMRS data yielded zerofield splitting parameters values consistent with those previously obtained for 1 and 2 from simulations of EPR data, corroborating the validity of the FDMRS-MCD approach. 2 ·1 In chapter 3, three Fe(II)-based, cubane-like complexes are presented, with formula [Fe(hmp)(MeOH)Cl]4 (complex 4), [Fe(hmp)(EtDH)Cl]4 (complex 5) and [Fe(hmp)(EtXan)]4 (complex 6). A study of the magnetic anisotropy and of the spin-spin coupling interactions in these complexes is described, which employed X-ray crystallography, Mossbauer spectroscopy and SQUID magnetometry. In addition, a detailed study was carried out on 4 and 5 by means of W-band EPR and MCD spectroscopies.2 Complexes 4-6 have been found to have a spin ground state S = 8 arising from ferromagnetic superexchange interactions, and a large positive anisotropy which has been estimated by means of simulations of the EPR and SQUID data. The fourth chapter deals with a heptanuclear, mixed-valence cluster complex with formula [FeII6FelII(hmp)12][BF4h (complex 7), which displays SMM behaviour. A preliminary study of the magnetic properties of this species is presented and correlated with its structural parameters. Two distinct relaxation processes have been detected in the solid state AC susceptibility measurements, while only one relaxation process is observed in solution as highlighted by ColeCole plots. Chapter 5 presents a series of compounds (8-17) that have been obtained serendipitously during the timeframe of this project. The preparation of these compounds is described, as well as a preliminary description of their structures. The sixth and final chapter draws final conclusions on the results presented in Chapters 2-5 and suggests desirable 3 ! :1 developments for the research outlined in this work, as well as the potential challenges and requirements for such developments. The crystallographic information files for complexes 3, 4, 5, 6 and 7 are included in electronic format on a DVD attached to the thesis. Two journal articles have also been published1,2 presenting the findings that we discuss here in chapter 2 and 3, and will be referred to in the text. References
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Jarvis, A. P. "Nickel complexes of acrylic monomers : mode of coordination and polymerisation studies." Thesis, University of Warwick, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246180.
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Chen, Chang-Nan. "Structure, characterization and kinetics of nickel complexes and reactions with biomolecules." Scholarly Commons, 2003. https://scholarlycommons.pacific.edu/uop_etds/2615.
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The macrocyclic square planar nickel complex, [Ni II CR] 2+ , has been shown to be a useful DNA or RNA structure probe due to its highly site- and conformation specific ability to induce cleavage on exposed guanine residues via the formation of a direct guanine N7-Ni III bond. Since the postulated intermediate [Ni III CR] 3+ is unstable, the detailed mechanism is unknown. In this study, the nature of the interaction of NiCR 2+ and its oxidized products with biomolecules was investigated. A study of the conversion of [Ni II CR] 2+ between a diamagnetic square planar structure and a paramagnetic tetragonal structure in aqueous solution has shown that the conversion is affected by the identity and the concentration of the counter anion. Of the anions studied, it is clear that Br − , ClO 4 − , and CF 3 SO 3 − have a higher ability to promote the conversion to the square planar form for [NiCR] 2+ than Cl − or CF 3 COO − . The oxidation reaction of [NiCR] 2+ with either KHSO 5 or Na 2 S 2 O 8 in a molar ratio of 1/1 resulted in the same stable complex [Ni(CR-2H)] 2+ . A single crystal x-ray diffraction study gave the structure of Ni(CR-2H)(ClO 4 ) 2 . In addition, kinetic studies revealed the oxidation reaction to be first order. The six protons on the two methyl groups of the macrocyclic ligand were also found to be sufficiently labile to exhibit hydrogen/deuterium exchange. The [Ni(CR-2H)] 2+ displays a higher acidity than [NiCR] 2+ by H/D exchange. This observation supports the conjecture that there is an enhanced dπ-pπ* back-bonding effect associated with the presence of the additional imine formed in [Ni(CR-2H)] 2+ . The [NI(CR-2H)] 2+ species with KHSO 5 also displays an oxidation ability similar to [NiCR] 2+ with KHSO 5 in the reaction with a 17 base pair synthetic oligonucleotide. This implies that [Ni(CR-2H)] 2+ is not just an oxidation product of [NiCR] 2+ , but may also play an important role in the reaction with guanine residues in oligonucleotides. The reactions of [NiCR] 2+ or [Ni(CR-2H)] 2+ with linoleic acid under a high concentration of Ni complexes (3.21 × 10 −3 M, 200 fold over linoleic acid) resulted in the unexpected reduced nickel complexes, (Ni 0 (CR-4H)-H + ) − - m/z 311.1 and (Ni 0 (CR-2H)-H + ) − - m/z 313.1, instead of the hydroperoxide product (HpODE-H + ) − - m/z 311.2.
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TASCEDDA, PATRICIA. "Electrocarboxylation d'heterocycles a trois chainons catalysee par des complexes de nickel." Nice, 1999. http://www.theses.fr/1999NICE5328.
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La methode electrochimique a anode soluble, combinee a une catalyse homogene par des complexes organometalliques, a ete utilisee pour l'electrocarboxylation d'heterocycles a trois chainons. Dans le cas de la reactivite des epoxydes, l'influence des differents parametres mis en jeu a montre que l'utilisation d'un complexe de nickel associe a un ligand tetraazote, tel que le cyclam, ainsi que du couple d'electrodes magnesium/inox, dans une solution de dmf contenant du kbr comme electrolyte support, s'averait tres efficace pour la carboxylation d'epoxydes monosubstitues par divers groupements fonctionnels, aboutissant aux carbonates cycliques correspondants dans de bons rendements. Toutefois, ces conditions reactionnelles se sont montrees moins efficaces pour l'electrocarboxylation des epoxydes disubstitues. Ce constat nous a amene a envisager une reactivite alternative de carboxylation en partant d'epoxydes aromatiques disubstitues portant un halogene en position ortho du noyau aromatique. L'acces a des derives d'isocoumarines ou a d'autres lactones a cinq chainons, selon le choix du catalyseur employe, constitue une nouvelle voie de synthese efficace et interessante. Les thiiranes, pouvant laisser presager une reactivite proche de celle des epoxydes, se sont montres tres peu reactifs en ce qui concerne leur electrocarboxylation mais ont abouti a la formation des alcenes correspondants. Dans le cas des aziridines, la methode electrochimique a permis d'acceder a des carbamates cycliques avec de bons rendements, dans des conditions reactionnelles tres proches de celles utilisees pour les epoxydes. Neanmoins, l'etude par voltametrie cyclique permet de supposer que les mecanismes de reaction de ces deux heterocycles a trois chainons sont relativement differents.
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EDISON, SARA ELIZABETH. "INVESTIGATION OF NICKEL (II)-OXIMATE COMPLEXES THAT REACT WITH MOLECULAR OXYGEN." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1085526904.
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Nelwamondo, Aubrey Ndifelani. "Solid state thermal decomposition of amide complexes of nickel(II) chloride." Thesis, Rhodes University, 1997. http://hdl.handle.net/10962/d1005008.
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The thermal decompositions of a series of amide complexes of nickel(II) chloride have been studied. Thermochemical, kinetic, structure and solid-state stability correlations have been investigated. Complexes containing homologous amide ligands (L) of the form NiLCℓ₂, Ni₃L₂Cℓ₆, Ni₃LCℓ₆, NiL₂Cℓ₂(2H₂0) and ML₂Cℓ₂ (where M = Ni(II), Co(II) or Cu(II)) have been prepared. Chemical analysis, spectral and thermogravimetric measurements were used to characterize the complexes and their decomposition stoichiometries. Three sets of reactions were identified as yielding stable products in a single step: (i) NiLCℓ₂ (s) → NiCℓ₂ (s) + L (g) (ii) Ni₃LCℓ₆ (s) → 3NiCℓ₂ (s) + 2L (g) (iii) Ni₃LCℓ₆ (s) → 3NiCℓ₂ (s) + L (g) Characterization of the processes in the ML₂Cℓ₂ and NiL₂Cℓ₂(2H₂0) complexes was not straightforward. Reaction enthalpies (ΔH) were determined using DSC. The orders of the reaction onset temperatures (Tc), peak temperatures (Tmax) and ΔHL values for the NiCℓ₂ system were: N-methylacetamide < acetamide < N-methylformamide, suggesting the importance of steric hindrance of the methyl-substituent groups in the amide skeleton. In the Ni₃LCℓ₆, NiL₂Cℓ₂(2H₂0) and ML₂Cℓ₂ systems no simple orders could be deduced. The Te and Tmax sequences obtained from analogous metal(II) chloride complexes indicated that the copper(II) complexes were the least stable. The kinetics of the loss of L from NiLCℓ₂ complexes were investigated using isothermal TG, non-isothermal TG and DSC measurements. The contracting geometry models described the course of the decompositions in the most satisfactory manner. Apparent activation energies ( Ea) were estimated from Arrhenius plots of rate coefficients from: (i) an approximate zero-order relationship, (ii) the contracting-area (R2) and contracting-volume (R3) equations, (iii) a new empirical (B2) expression, (iv) the half-life ( 1/t₀.₅) and (v) the characteristic feature of the rate-time curve ( 1/tmax/2 ). The non-dependence of Ea on the rate equation used supports the reliability of the kinetic parameters. Non-isothermal experiments were analyzed by the Coats-Redfern, the modified BorchardtDaniels and the Kissinger methods. Arrhenius parameters were in keeping with results from the isothermal kinetic measurements. The values of Ea obtained for the NiLCℓ₂ system increased with an increase in basicity of the amide ligands. No straightforward correlation was found between Ea and Te, Tmax, ΔHL or spectral properties.
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Edison, Sara E. "Invesitgation of nickel(II)-oximate complexes that react with molecular oxygen." Cincinnati, Ohio : University of Cincinnati, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=ucin1085526904.
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Manuel, Antonio David. "Dioxygen activation with Bis(arylimino)pyridine radical anion complexes of nickel." Diss., University of Iowa, 2014. https://ir.uiowa.edu/etd/4686.
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Complexes of redox-active ligands have received increasing attention, in part, because they have been shown to facilitate a variety of bond-forming and bond-breaking reactions, including the activation of small molecules. Unique attributes of redox-active ligands include that they influence the electronic properties of transition metal complexes and may participate in their multielectron redox chemistry. In this work, the utility of Ni complexes of redox-active bis(arylimino)pyridine ligands for the activation of dioxygen was explored. A series of bis(arylimino)pyridine complexes [Ni{2,6-(ArN=CMe)2C5H3N}Cl2](where Ar = 4-X-2,6-iPr2C6H2 and X = H, Cl, Br, NO2, or N(CH3)2) were synthesized along with the deuterium-labeled complex [Ni{2,6-(ArN=CCD3)2C5H3N}Cl2](where Ar = 2,6-iPr2C6H3).Characterization by X-ray crystallography of three complexes confirmed coordination of the Ni center by the three nitrogen donor atoms of the bis(arylimino)pyridine ligand and two chloro ligands. The structural analyses further revealed a distorted square pyramidal geometry of the Ni centers. The reduced complexes[Ni{2,6-(ArN=CMe)2C5H3N}Cl](where Ar = 4-X-2,6-iPr2C6H2 and X = H, Cl, or Br) and [Ni{2,6-(ArN=CCD3)2C5H3N}Cl](where Ar = 2,6-iPr2C6H3) were synthesized by reaction of the corresponding dichloride complexes with a sodium amalgam. These are four-coordinate complexes with distorted square planar geometry and are best characterized as ligand-radical complexes of NiII as opposed to NiI complexes on the basis of X-ray crystallography and electron paramagnetic resonance spectroscopy of Ni{2,6-(2,6-iPr2C6H3N=CMe)2C5H3N}Cl]. Reactions of the ligand-radical NiII complexes with dioxygen were studied by UV-Vis spectroscopy, and the overall course of the reaction was similar for all four complexes. The half-life of the reaction was not affected by deuterium labeling of the acetimino methyl groups but was affected by different substituents in the 4-position of the phenyl groups of the ligand. The reactions caused intraligand C-C bond cleavage with formation of a new C=O double bond, resulting in the complexes [Ni{6-(ArN=CMe)C5H3N-2-C(O)NAr}Cl] (where Ar = 4-X-2,6-iPr2C6H2 and X = H, Cl, or Br) and [Ni{6-(ArN=CCD3)C5H3N-2-C(O)NAr}Cl](where Ar = 2,6-iPr2C6H3). The structures of the complexes [Ni{6-(ArN=CR)C5H3N-2-C(O)NAr}Cl] (where Ar = 2,6-iPr2C6H3 and R = CH3 or CD3) were determined by X-ray crystallography. For all four complexes, the carboxamidato group was identified by a strong band in the infrared spectra assignable to the CO stretching vibration. Furthermore, the new carboxamidato ligands were removed from the metal center and isolated in their neutral form as 6-(ArN=CMe)C5H3N-2-C(O)NHAr (where Ar = 4-X-2,6-iPr2C6H2 and X = H, Cl, or Br) and 6-(ArN=CCD3)C5H3N-2-C(O)NHAr(where Ar = 2,6-iPr2C6H3). Taken together, these results indicate that the activation of dioxygen occurs at the ligand and without an overall oxidation state change at the Ni center. The observed ligand-centered oxygenation in these reactions contrasts with the prevailing metal-centered chemistry of redox-active bis(arylimino)pyridine complexes and demonstrates that they can be directly involved in the activation and conversion of a small molecule.
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Travers, Guy. "New bis(benzimidazol-2-ylidene)pyridine-nickel complexes as homogeneous catalysts." Thesis, Curtin University, 2015. http://hdl.handle.net/20.500.11937/450.
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New nickel-based catalysts for carbon-carbon bond formation reactions were synthesized and tested. The catalysts were found to be effective, but not strongly influenced by changes in the catalyst structure. During the course of this work, an organic precursor was found to catalyse the decomposition of dimethylsulfoxide. A product of the decomposition was isolated in good yield and identified. This product was found to be a useful reagent for epoxidation reactions.
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Lourak, Mouhsine. "Couplages symétriques et mixtes de dérivés halogènes aromatiques et hétéroaromatiques par les réducteurs complexes." Nancy 1, 1990. http://www.theses.fr/1990NAN10140.
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Il a été montré au cours de ce mémoire que les réducteurs complexes sont des agents performants pour le couplage symétrique de dérivés halogènes aromatiques, surtout les dérivés chlorés, ce qui n'est pas le cas avec la plupart des méthodes de la littérature. Nous avons montré : 1) Que les substituants tels que : hydroxyle, nitrile, thiométhyle, cétone et aldehyde bloqués sont tolérés par cette méthode ; 2) Que la position du substituant sur le noyau aromatique n'influe pratiquement pas sur la réaction ; 3) Que la présence d'un iodure alcalin accélère cette réaction dans tous les cas et permet aux dérivés chlorés une meilleure réactivité. Ces résultats ont permis de proposer des hypothèses d'un mécanisme que l'expérience a vérifiée qui tient compte à la fois des structures supposées des réducteurs complexes, des observations au cours de l'étude et des mécanismes proposés dans la littérature. Un système très efficace a été mis au point par la suite permettant le couplage mixte de dérivés halogènes aromatiques dans de bonnes conditions. Il a été montré également que les réducteurs complexes présentent d'excellentes propriétés pour le couplage de dérivés halogènes hétéroaromatiques azotés et sulfurés. Les réducteurs complexes au nickel permettent de réaliser le couplage de dérivés hétéroaromatique sulfurés. Enfin, dans le but d'étendre le champ d'application des réducteurs complexes, les essais de couplage mixte aromatique-hétéroaromatique et hétéroaromatique-hétéroaromatique montrent que ce type de couplage est possible et qu'ils pourraient constituer une nouvelle application des Réducteurs Complexes au nickel
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Werhun, Peter. "Nuclear Magnetic Resonance of Low-Receptivity Nuclides: The First Demonstration of 61Ni SSNMR as Applied to Structural and Crystallographic Characterization of Diamagnetic Nickel Complexes." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36525.
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Nuclear magnetic resonance (NMR) spectroscopy has proven to be an invaluable tool for the modern chemist, despite being a relatively insensitive spectroscopic technique. However, it is precisely this insensitivity that limits characterization of low-receptivity nuclides, which make up the bulk of transition metal nuclides, in particular. In this work, high-fields were used to collect the first 61Ni solid-state NMR (SSNMR) spectra of diamagnetic nickel compounds, specifically, bis(1,5-cyclooctadiene)nickel(0) (Ni(cod)2), tetrakis(triphenylphosphite)nickel(0) (Ni[P(OPh)3]4), and tetrakis(triphenylphosphine)nickel(0) (Ni(PPh3)4). This was complemented by NMR study of the co-ordinated ligands and 61Ni density functional theory (DFT) computations.
61Ni SSNMR spectra of Ni(cod)2 were used to determine its isotropic chemical shift (δiso = 965 ± 10 ppm), span (Ω = 1700 ± 50 ppm), skew (κ = -0.15 ± 0.05), quadrupolar coupling constant (CQ = 2.0 ± 0.3 MHz), quadrupolar asymmetry parameter (η = 0.5 ± 0.2), and the relative orientation of the chemical shift and EFG tensors. Solution study of Ni(cod)2 saturated in C6D6 yielded a narrow 61Ni signal, and the temperature dependence of δiso(61Ni) was assessed (δiso being 936.5 ppm at 295 K). The solution is proposed as a secondary chemical shift reference for 61Ni NMR in lieu of the extremely toxic Ni(CO)4 primary reference. For Ni[P(OPh)3]4, 61Ni SSNMR was used to infer the presence of two distinct crystallographic sites and establish ranges for δ¬iso in the solid state, as well as an upper bound for CQ (3.5 MHz for both sites). For Ni(PPh3)4, fitting provided a δiso value of 515 ± 10 ppm, Ω of 50 ± 50 ppm, κ of 0.5 ± 0.5, CQ of 0.05 ± 0.01 MHz, and η of 0.0 ± 0.2. Ni(cod)2 was chosen for study as it is a ubiquitous source of nickel(0), used for both further synthesis of nickel(0) compounds and directly as a catalyst. The study of Ni[P(OPh)3]4 and Ni(PPh3)4 demonstrated the utility of 61Ni SSNMR given the lack of a previously reported crystal structure for both and the transient nature of Ni(PPh3)4 in solution.
The work begins in Chapter 1 by introducing the interactions fundamental to NMR spectroscopy, before moving on to briefly review the field of transition metal nuclide NMR, the chemistry of nickel (with an emphasis on homogeneous catalysis with nickel(0)), and the literature with respect to nickel NMR up to this point. In Chapter 2, the theory and practice of NMR are explained, including solid-state NMR, as well as the basic principles of density functional theory NMR computations. The specific experimental and computational methods of this work are also introduced. Lastly, in Chapter 3 the results are discussed in the context of the concepts presented and literature reviewed, and highlight the use of 61Ni NMR as a means to gain novel information about the chemistry of the compounds studied.