Author: Padmapriya Srinivasan
Publisher:
ISBN:
Category : Green chemistry
Languages : en
Pages : 0
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Green Chemistry initiatives have recently been at the forefront of both industrial and academic communities in order to address fundamental scientific challenges of protecting human health and the environment. The Twelve Principles of Green Chemistry, of which catalysis is a primary tenet and the main motivation for this project, has led the path to reduce waste production in the chemical industry. The principle of catalysis states that catalytic reactions necessarily produce less waste than stoichiometric reactions. Traditionally, precious and toxic heavy transition metals such as platinum and palladium have been used as metal centres in catalysts because of their stability, favourable redox properties, and ease of characterization. These concerns prompted this research in finding more environmentally friendly alternatives as metal centres in catalysis, such as main group complexes. Indium is a heavy main group metal that is environmentally benign. It is most stable in the +3 oxidation state and, notably, does not possess other readily accessible oxidation states. To make indium complexes redox-active, so-called "non-innocent" redox-active ligands are being explored. The current work seeks to synthesize a series of redox-active indium catalysts with varied steric bulk about the indium centre and different redox-active ligands. The goals of this study are to first synthesize and structurally characterize organometallic indium compounds with the redox-active ligand 2-amninobenzenethiol, and then test the reactivity of indium complexes with dithiolate ligands using mild oxidizing agents. A third goal is to use DFT methods to rationalize the synthesized complexes in terms of structure, reactivity, bonding motifs, and in interpreting the experimental spectroscopic data.
Author: Ryan A. Zarkesh
Publisher:
ISBN: 9781267171108
Category :
Languages : en
Pages : 150
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This dissertation describes the synthesis and reactivity of tantalum metal complexes containing a tridentate redox-active ligand. Fundamental studies have focused on utilizing the redox-active ligand to store multiple electron equivalents for oxidative addition and reductive elimination reactions. Chapter 1 provides an introduction to the characteristics of redox-active ligands and provides an overview of group transfer reactions involving redox-active ligands. The previous published results of bidentate redox-active ligands coordinated to Group IV d0 metals are discussed in terms of their decomposition side reactions. Chapter 2 describes the coordination of a known tridentate redox-active bis(phenoxy)amide ligand, (ONO), to a d0 tantalum(V) metal center and the examination of the redox properties of the resulting chloro oxidation products by electrochemical and spectroscopic methods. Chapter 3 examines the reactivity of the (ONO)TaR2 complexes in the general context of organometallic chemistry with a focus on protonolysis and reactivity with aryl azides, a known source of nitrene fragments upon oxidation. Chapter 4 examines the reactivity of the (ONO)TaX2 (X = Me, Cl) compounds with bulky diazoalkanes, a known carbene transfer reagent. The (ONO)TaCl2 complex proved to be a competent catalyst to generate cyclopropanes from styrene and the corresponding diazoalkane. Chapter 5 explores the utilization of the (ONO) ligand to store electron equivalents for the catalytic nitrene-nitrene coupling reactions with organoazides to afford organodiazenes. Finally, Chapter 6 addresses the electronic considerations of a related redox-active triamido ligand in an effort to tune the ligand's redox potentials.
Author: Maddie Greatorex
Publisher:
ISBN:
Category : Analytical chemistry
Languages : en
Pages : 0
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Author: Nicole Annette Ketterer
Publisher:
ISBN:
Category :
Languages : en
Pages : 368
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Author: Baixin Qian
Publisher:
ISBN:
Category : Aluminum compounds
Languages : en
Pages : 362
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![Synthesis, Characterization, and Reactivity Studies of Iron Complexes Supported by the Redox-active [ONO] Ligand PDF](https://books.google.com/books/content/images/frontcover/pBHwrQEACAAJ?fife=w80-h100)
Author: Janice Lin Wong
Publisher:
ISBN: 9781321094466
Category :
Languages : en
Pages : 123
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The work reported herein primarily focuses on the development of new platforms for multi-electron reactivity using iron complexes supported by a redox-active pincer-type ligand. This dissertation details the synthesis, characterization, and reactivity of iron complexes coordinated to the redox-active [ONO] ([ONO]H3 = bis(3,5-di-[tert]-butyl-2-phenol)amine) ligand. Chapter 1 provides a general background on ligand-centered and metal-centered redox reactivity. Specifically, the characteristics of redox-active ligands and their ability to promote multi-electron reactivity at redox-inert metal centers is presented. In addition, iron-catalyzed organic transformations in which the metal center undergoes redox changes is also discussed. Finally, ligand-enabled redox reactions mediated by iron complexes containing redox-active ligands is described. Chapter 2 reports on the complexation of bis(3,5-di-[tert]-butyl-2-phenoxy)amine, [ONHO], and the redox-active [ONO] ligands by iron centers to afford a new family of iron complexes. Characterizations of each compound through a battery of analytical techniques reveal the oxidation states of the metal center and ligand. Furthermore, the electronic properties of each complex were investigated in order to evaluate their potential to facilitate multi-electron reactivity. Chapter 3 details the reactivity of the [ONO]Fe platform. Metathesis reactions are conducted with [ONO [superscript q] Fe [superscript III] X2 (X = Cl, N[SiMe3]2 complexes, demonstrating the capability of the fully-oxidized [ONO [superscript q]−1 to act as a two-electron acceptor to generate the fully reduced [ONO [superscript cat]3− that is coordinated to an iron(III) center. Similarly, oxidation of [ONO[superscript cat] Fe [superscript III] (py)3 (py = pyridine) using dihalogens result in two-electron oxidations of the tridentate ligand while the metal oxidation state remains the same. These redox reactions showcase the ability of the [ONO] ligand platform to undergo reversible two-electron oxidation state changes, allowing multi-electron reactivity to occur at the iron center. The synthesis and characterization of two novel bimetallic complexes of the form [ONO]M'[ONO]2 M (M' = Fe, Zn; M = Fe) are presented in Chapter 4. The rich redox profiles of both complexes suggest that they can potentially impart unique cooperative bimetallic reactivity. The synthetic techniques developed to prepare these complexes lay the foundation for a general method to access new bimetallic combinations that could be promising for multi-electron reactivity. Finally, Chapter 5 discusses the synthesis, characterization, and electronic comparisons between two homoleptic tris-iminosemiquinonate chromium(III) compounds. While one is coordinated to three N,N'-bis(3,5-dimethylphenyl)acenapthenediimino-semiquinonate, (dmp-ADI [superscript sq])1−, ligands, the other contains three N,N'-bis(3,5-dimethylphenyl)phenanthrenediimino-semiquinonate, (dmp-PDIsq)1− ligands. The differences in the electronic properties between each complex likely stems from variation in the diimine ligand backbones. However, further investigation is required to completely understand the complicated behaviors of such complexes, both of which apparently exhibit intramolecular anti-ferromagnetic properties.
Author: Michael Mosher
Publisher:
ISBN:
Category : Catalysts
Languages : en
Pages : 0
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Author: Rachel Vanderkloet
Publisher:
ISBN:
Category : Green chemistry
Languages : en
Pages : 80
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Author: Aaron M. Hollas
Publisher:
ISBN: 9781369227055
Category :
Languages : en
Pages : 188
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The work described herein focuses on the ability of redox-active ligands to enable multi-electron reactivity at transition metal centers. A parallel theme is the effect of ancillary ligands on controlling and modulating the electronic structure of the redox-active ligand and metal center in addition to ancillary ligand effects as they relate to controlling the primary coordination sphere of the metal. (Abstract shortened by ProQuest.).
Author: David B.S. MacDonald
Publisher:
ISBN:
Category : Indium compounds
Languages : en
Pages : 80
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