Electrochemical Studies on Transition Metal Complexes of Some N-heterocyclic Multidentate Ligands PDF Download
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Author: Pham Dai Hung
Publisher:
ISBN:
Category : Organometallic compounds
Languages : en
Pages : 372
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Author: Pham Dai Hung
Publisher:
ISBN:
Category : Organometallic compounds
Languages : en
Pages : 372
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Author: Samuel Ian Woodburn
Publisher:
ISBN:
Category : Transition metals
Languages : en
Pages : 392
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Author: Remi Chauvin
Publisher: Springer Science & Business Media
ISBN: 3642047211
Category : Science
Languages : en
Pages : 260
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This book is part of a series that gives the broad scientific readership a comprehensive summary and critical overview of specific topics in the field of organometallic chemistry. This text focuses on transition metal complexes of neutral eta1-carbon ligands.
Author: Sergio Santiago Rozenel
Publisher:
ISBN:
Category :
Languages : en
Pages : 256
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Abstract Transition metal complexes with multidentate phosphorous/nitrogen ligands. Synthesis, characterization and reactivity. By Sergio Santiago Rozenel Doctor in Philosophy in Chemistry University of California, Berkeley Professor John Arnold, Chair Chapter 1: Chromium complexes supported by the multidentate monoanionic ligand [N2P2] {H[N2P2] = tBuN(H)SiMe2N(CH2CH2PiPr2)2} are presented, and the activity of these complexes towards ethylene oligomerization/polymerization is examined. The complexes [N2P2]CrCl2 (1) and [N2P2]CrCl (2) polymerized ethylene after activation with MAO. Derivatives of 1 and 2 were synthesized in order to gain insights about the active species in the ethylene oligomerization/polymerization processes. The alkyl complexes [N2P2]CrMe (3), [N2P2]CrCH2SiMe3 (4) and [N2P2]Cr(Cl)CH2SiMe3 (5), the cationic species {[N2P2]CrCl}BF4 (7), {[N2P2]CrCl}BPh4 (8) and {[N2P2]CrCH2SiMe3}BF4 (9), and the Cr(II) complex [N2P2]CrOSO2CF3 (11) were not active ethylene oligomerization/polymerization catalysts in absence of an activator. Reaction of 1 with two equivalents of MeLi led to reduction to 3. However, with one equivalent of MeLi the stable mixed alkyl-halide derivative [N2P2]Cr(Cl)Me (6) was obtained. Reaction of 2 with Red-Al® produced the hydride ([N2P2]Cr)2(ì-H)2 (10), which reacted with CO to produce the Cr(I) complex [N2P2]Cr(CO)2 (12). Reduction of 2 with KC8 in the presence of p-tolyl azide produced the dimeric cis μ-imido ([N2P2]Cr)2(ì-NC7H7)2 (13). A similar reduction in the presence of ethylene resulted in the isolation of the Cr(III) metallacyclohexane compound [N2P2]CrC4H8 (14). Chapter 2: A series of Co, Ni and Cu complexes with the ligand HN(CH2CH2PiPr2)2 (HPNP) has been isolated and their electrochemical behavior investigated by cyclic voltammetry. The nickel complexes [(HPNP¬)NiOTf]OTf and [(HPNP)NiNCCH3](BF4)2 display reversible reductions, as does the related amide derivative (NP2)NiBr. Related copper(I) and cobalt(II) derivatives were isolated and characterized. Addition of piperidine to [(HNP2)NiNCCH3](BF4)2 led to the formation of the new species [(HPNP)Ni(N(H)C(CH3)NC5H10)](BF4)2. Nucleophilic addition of piperidine to acetonitrile to produce HN=C(CH3)NC5H10 was catalyzed by [(HPNP)NiNCCH3](BF4)2. Chapter 3: A series of bimetallic ruthenium complexes [HPNPRu(N2)]2(μ-Cl)2](BF4)2 (2), [(HPNPRu(H2)Cl)2(μ-Cl)2](BF4)2 (3), [(HPNPRu)2(μ-H2NNH2)(μ-Cl)2](BF4)2 (4), [(HPNPRu)2(μ-Cl)2(μ-HNNPh)](BF4)2 (5), [HPNPRu(NH3)(ç2-N2H4)](BF4)Cl (6), [(HNP2Ru)2(μ-Cl)2(μ2-OSO2CF3)]OSO2CF3 (7), [HPNPRu]2(μ-Cl)3]BPh4 (8) and [HPNPRu]2(μ-Cl)3]BF4 (9) were isolated and characterized in the course of reactions aimed at studying the reduction of N2 and hydrazine. Complex 4 produces ammonia catalytically from hydrazine, and complex 2 generates ammonia upon reaction with Cp2Co/HLuBF4. DFT calculations support the idea that the diazene complex formed is more stable than the expected Chatt-type intermediate. Chapter 4: The reduction chemistry of cobalt complexes with the PNP ligand was explored. Reaction of (HPNP)CoCl2 (1) with n-BuLi generated the deprotonated Co(II) product (PNP)CoCl (2), and the Co(I) reduced species (HPNP)CoCl (3). The reaction of complex 2 with KC8 was investigated, where it was found that the products obtained depended upon the inert gas used to carry out the reaction: (PNP)CoN2 (4) under N2, bimetallic complex [(PNP)Co]2 (5) under Ar, and (HPNP)Co(H)3 (8) under H2. Complex 5 reacted with H2 to generate the bimetallic complex [(PNP)CoH]2 (6). With H2, H3SiPh and AgBPh4 complex 3 generated the species (HPNP)CoCl(H)2 (9), (HPNP)CoCl(H)SiH2Ph (10) and [(HPNP)CoCl]BPh4 (11) respectively. DFT calculations were performed to gain insights about the transformations observed.
Author: Ashleigh Lauren Ward
Publisher:
ISBN:
Category :
Languages : en
Pages : 113
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Chapter 1: A series of actinide-transition metal heterobimetallics have been prepared, featuring thorium, uranium and cobalt. Complexes incorporating the binucleating ligand N[o-(NHCH2PiPr2)C6H4]3 with either Th(IV) (1.4) or U(IV) (1.5) and a carbonyl bridged [Co(CO)4]- unit were synthesized from the corresponding actinide chlorides (Th: 1.2; U: 1.3) and Na[Co(CO)4]. Irradiation of the resulting isocarbonyls with ultraviolet light resulted in the formation of new species containing actinide-metal bonds in good yields (Th: 1.6; U: 1.7); this photolysis method provides a new approach to a relatively unusual class of complexes. Characterization by single-crystal X-ray diffraction revealed that elimination of the bridging carbonyl and formation of the metal-metal bond is accompanied by coordination of a phosphine arm from the N4P3 ligand to the cobalt center. Additionally, actinide-cobalt bonds of 3.0771(5) Å and 3.0319(7) Å for the thorium and uranium complexes, respectively, were observed. The solution-state behavior of the thorium complexes was evaluated using 1H, 1H-1H COSY, 31P and variable-temperature NMR spectroscopy. IR, UV-vis/NIR, and variable-temperature magnetic susceptibility measurements are also reported. Chapter 2: The first examples of actinide complexes incorporating corrole ligands are presented. Thorium(IV) and uranium(IV) macrocycles of Mes2(p-OMePh)corrole were synthesized via salt metathesis with the corresponding lithium corrole in remarkably high yields (93% and 83% respectively). Characterization by single-crystal X-ray diffraction revealed both complexes to be dimeric, having two metal centers bridged via bis([mu]-chlorido) linkages. In each case, the corrole ring showed a large distortion from planarity, with the Th(IV) and U(IV) ions residing unusually far (1.403 Å and 1.330 Å respectively) from the N4 plane of the ligand. 1H NMR spectroscopy of both the Th and U dimers revealed dynamic solution behavior. In the case of the diamagnetic Th corrole, variable-temperature, DOSY and EXSY 1H NMR spectroscopy was employed, and supported that this behavior was due to an intrinsic pseudorotational mode of the corrole ring about the M-M axis. Additionally, the electronic structure of the actinide corroles was assessed using UV-visible spectroscopy, cyclic voltammetry and variable-temperature magnetic susceptibility. This novel class of macrocyclic complexes provides a rich platform in an underdeveloped area for the study of non-aqueous actinide bonding and reactivity. Chapter 3: A series of divalent first row triflate complexes supported by the ligand tris(2-pyridyl(methyl))amine (TPA) have been investigated as oxygen reduction catalysts for fuel cell applications. [(TPA)M2+]n+ (M= Mn, Fe, Co, Ni and Cu) derivatives were synthesized and characterized by X-ray crystallography, cyclic voltammetry, NMR spectroscopy, magnetic susceptibility, IR spectroscopy and conductance measurements. The stoichiometric and electrochemical O2 reactivity of the series were examined. Chapter 4: Complexes of the ligand tris(2-pyridyl(methyl))amine (TPA) {[(TPA)M2+]n+ (M= Mn, Fe, Co and Cu)} presented in chapter 3 were evaluated as electrocatalysts for oxygen reduction. Rotating-ring disk electrode (RRDE) voltammetry was used to examine the catalytic activity of the series of complexes on a carbon support in acidic media, emulating fuel cell performance. The iron complex displayed a selectivity of 89% for four-electron conversion and demonstrated the fastest reaction kinetics, as determined by a kinetic current of 7.6 mA. Additionally the Mn, Co and Cu complexes all showed selective four-electron oxygen reduction (
Author: Eleanor Magdzinski
Publisher:
ISBN:
Category :
Languages : en
Pages : 214
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The synthesis of transition metal complexes containing redox-active ligands or ligands with redox-active substituents have been areas of ongoing interest in chemical research. To date, only a handful of examples involving redox-active ligands containing main group centres have been reported. This thesis presents work on the development of novel redox-active ligands utilizing an assortment of nitrogen-based frameworks (diiminopyridine (DIMPY), 1,4-diaza-1,3-butadiene (DAB), N-heterocyclic carbene (NHC)) that contain metallocene substituents (ferrocene and an understudied redox-active Co(III) moiety). Initially the syntheses of an N, N'-differocenyl diiminopyridine and its low-valent chalcogen (S2+, Se2+, Te2+) and pnictogen (P+) complexes are discussed. These complexes represent the first such examples of utilizing low-valent main group systems containing redox-active ligands with pendant ferrocenyl substituents. Other work focuses on the synthesis of the above listed nitrogen-based ligands containing novel mixed sandwich Co(III) substituents, and include comparative reactivity studies (SnCl2 and GeCl2.dioxane for DIMPY and SnCl4 and Pt2Me4(SMe2)2 for DAB) of those ligands to their ferrocene derivatives. Electrochemical studies reveals an instability of the Co(III) containing complexes, leading to the continuous variation in the ligand framework towards a more stable compound.
Author: John L Burmeister
Publisher: World Scientific
ISBN: 9814488003
Category : Science
Languages : en
Pages : 654
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This invaluable book distils the research accomplishments of Professor Fred Basolo during the five decades when he served as a world leader in the modern renaissance of inorganic chemistry. Its primary focus is on the very important area of chemistry known as coordination chemistry.Most of the elements in the periodic table are metals, and most of the chemistry of metals involves coordination chemistry. This is the case in the currently significant areas of research, including organometallic homogenous catalysis, biological reactions of metalloproteins, and even the solid state extended structures of new materials. In these systems, the metals are of primary importance because they are the sites of ligand substitution or redox reactions. In the solid materials, the coordination number of the metal and its stereochemistry are of major importance.Some fifty years of research on transition metal complexes carried out in the laboratory of Professor Basolo at Northwestern University is recorded here as selected scientific publications. The book is divided into three different major research areas, each dealing with some aspect of coordination chemistry. In each case, introductory remarks are presented which indicate what prompted the research projects and what the major accomplishments were. Although the research was of the academic, curiosity-driven type, some aspects have proven to be useful to others involved in projects that were much more applied in nature.
Author: Githa Susan Srivatsa
Publisher:
ISBN:
Category : Bioelectrochemistry
Languages : en
Pages : 432
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Author: Mohammad Sorour El-Saeed El-Shahawi
Publisher:
ISBN:
Category : Transition metals
Languages : en
Pages : 598
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Author: Satcher, Jr. (Joe Harold)
Publisher:
ISBN:
Category :
Languages : en
Pages : 622
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