Coordination Chemistry of Multidentate Ligands from a Multi-component Reaction

Coordination Chemistry of Multidentate Ligands from a Multi-component Reaction
Author: Ann Almesaker
Publisher:
Total Pages: 250
Release: 2009
Genre:
ISBN:

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The application of a multi-component reaction approach has been explored in the synthesis of intricate ligands incorporating the commonly employed ligand motifs bis(2-pyridylmethyl)amine (bPMA) and tris(2-aminoethyl)amine (tren). The synthesis of these ligands demonstrates that multi-component reactions can be an area with high exploratory power in ligand syntheses as they have the potential to afford ligands with a diverse variety of structures by a simple methodology.The coordination chemistry of one bPMA based ligand has been examined with a range of transition metal ions (i.e. MnII, CoII and CuII). The structures of several of these products have been determined by X-ray crystallography and their properties examined by various spectroscopic methods. The complexes are discussed in terms of similarities and differences in the solid state between the different metal ions in combination with different counter ions. Mononuclear and dinuclear complexes, and one case of a 1D coordination polymer were isolated.The spectroscopic properties of copper(II) complexes formed by two analogous tren based ligands were studied. From these studies, it could be concluded that the two ligands formed analogous complexes in both solution and in the solid state. Data on three of the copper(II) tren complexes were collected using synchrotron radiation due to the small size of the isolated crystals. These complexes were found to have trigonal bipyramidal coordination geometry around the mononuclear copper(II) centre. Two isomeric copper(II) nitrate complexes with minor differences in the copper(II) geometries were isolated. In addition, a copper(II) fluoride complex [CuLF]BF4·THF (L = tren based ligand) was studied which interestingly exhibited a very short Cu-F bond, in fact theshortest reported to present time.The copper(II) complexes were further investigated in catalytic oxidation reactions and small ion stabilisation studies. The complexes had poor catalytic activity in catechol oxidation and in oxidative coupling of 2,6-di-tert-butylphenol. However, the bPMA based copper(II) complex showed an initially relatively high catalytic activity in the oxidative coupling reaction, but underwent deactivation. The complexes were not worthy of further investigation in these reactions due to the low catalytic activity. Preliminary results pointed to the fact that the tren based ligands were able to stabilise Cu-OOH species in the solution at low temperatures (-60 and -80 °C). Such complexes are of interest in the elucidation of enzymatic mechanisms of monooxygenases such as peptidylglycine [alpha]-hydroxylating monooxygenases and dopamine [beta]-monooxygenases. These Cu-OOH complexes also demonstrated evidence of partial ligand oxidation upon warming the solutions containing the complexes.Overall a range of ligands structures with intricate structures have been synthesised by a multi-component approach and used to prepare transition metal complexes (CuII, CoII and MnII) which display interesting properties due to the unusual ligand frameworks with large pendant substituents.

Reactions of Coordinated Ligands

Reactions of Coordinated Ligands
Author: P.S. Braterman
Publisher: Springer Science & Business Media
Total Pages: 419
Release: 2012-12-06
Genre: Science
ISBN: 1461307554

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This, the second and final volume of Reactions of Coordinated Ligands, describes the chemistry of ligands bound through non-carbon atoms, and of coordinated carbon dioxide. As before, emphasis is on the underlying mechanisms, which provide a unity of understanding for superficially disparate processes. The wide range of topics covered illustrates well both the versatility and the usefulness of coordination chemistry in the controlled activation of ligands. Looking to the future, carbon dioxide is the feedstock of last resort. The homogeneous reduction of dinitrogen to ammonia now seems unlikely to replace the Haber process, but solution reactions also lead to more complex, varied, and valuable products. Nitrogen monoxide, a "non innocent" ligand, impinges as pollutant and reagent. Its rich chemistry stems from its linked roles as three-electron donor, and as extremely powerful -acceptor. In the hydrolysis and condensation of complexed amides, esters etc. , metals act both as templates and as tunable and poly functional Lewis acids. Here the control of hydrophobic and steric interactions begins to model the subtle mechanisms of biological specificity. Finally, phosphorus and sulfur are imporant both as ligand atoms in themselves, and as anchors for other functionalities. I would like to thank all those who have been involved in the writing and production of this work, and also my colleagues old and new, at Glasgow and the University of North Texas, for their support. Paul S. Braterman v CONTENTS 1. Reactions of Coordinated Carbon Dioxide 1 J. D. Miller 1.

Synthetic Coordination and Organometallic Chemistry

Synthetic Coordination and Organometallic Chemistry
Author: Alexander D. Garnovskii
Publisher: CRC Press
Total Pages: 559
Release: 2003-04-25
Genre: Science
ISBN: 0203911520

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This reference describes standard and nonstandard coordination modes of ligands in complexes, the intricacies of polyhedron-programmed and regioselective synthesis, and the controlled creation of coordination compounds such as molecular and hn-p-complexes, chelates, and homo- and hetero-nuclear compounds. It offers a clear and concise review of modern synthetic techniques of metal complexes as well as lesser known gas- and solid-phase synthesis, electrosynthesis, and microwave and ultrasonic treatment of the reaction system. The authors pay special attention to o-hydroxyazomethines and their S-, Se-containing analogues, b-diketones, and quinines, among others, and examine the immediate interaction of ligands and metal salts or carbonyls.

Multi-component Reactions in Molecular Diversity

Multi-component Reactions in Molecular Diversity
Author: Jean-Philippe Goddard
Publisher: John Wiley & Sons
Total Pages: 151
Release: 2019-12-19
Genre: Science
ISBN: 1119687438

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While very useful for studying syntheses of molecular diversity, multi-component reactions also offer rapid access to a variety of complex molecules that are relevant for biological applications. Multi-component Reactions in Molecular Diversity analyzes these reactions, whether they are realized by organometallic, ionic or even radical processes. It highlights popular methods based on monotype reactions (cascade, tandem, domino) and their efficiency and academic industrial domain are illustrated. This book also investigates the most efficient ways to prepare complex molecules. Multi-component reactions are in tune with the concepts of atom and steps economy, which are of prior importance in all the reported processes ? from the laboratory to the pilot scale. The essential criteria for green chemistry are also examined in the book in detail.

Synthetic Coordination Chemistry: Principles And Practice

Synthetic Coordination Chemistry: Principles And Practice
Author: Julian A Davies
Publisher: World Scientific
Total Pages: 472
Release: 1996-09-20
Genre: Science
ISBN: 9814501131

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Although coordination chemistry naturally centers on the synthesis of coordination compounds, the synthesis of these materials is typically not an end in itself. Coordination compounds are utilized in all branches of chemistry; from theoretical modeling to industrial and consumer products. While a large amount of information is available on coordination chemistry in general and synthetic methods in particular, no comprehensive work has been presented on the preparation of coordination compounds with an emphasis on synthetic strategies rather than on detailed descriptions of specific syntheses. The goal of this book is to provide an approach to coordination chemistry that is based upon preparative strategies.The main aim of the authors is to present a systematic classification of synthetic reactions rather than an encyclopedic listing of experimental results. Hence, the coverage is more selective than exhaustive. Despite this, the book provides access to the original literature with ca. 2000 references. The edition is well-illustrated and contains almost 250 schemes, figures and illustrations of crystal structures of selected complexes.

Variety in Coordination Modes of Ligands in Metal Complexes

Variety in Coordination Modes of Ligands in Metal Complexes
Author: Shinichi Kawaguchi
Publisher: Springer Science & Business Media
Total Pages: 129
Release: 2012-12-06
Genre: Science
ISBN: 3642501486

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Metal complexes play important roles as catalysts or other participants in synthetic and biological reactions. Substrates and sometimes attacking reagents also are activated through coordination with metal atoms or ions. In these events the natures not only of the central metals but also of ancillary ligands exert important influences on the stability and reactivity of the coordinated substrates. A ligand in general can adopt various coordination modes depending on its chemical environment, thus functioning as a probe. The number of coordination modes increases with increasing complexity of the ligand. In this book it is shown that even the simplest mono- and diatomic ligands such as H, CO, and N2 exhibit a variety of coordination modes, which are related to their reactions. The thiocyanate anion is taken up as a representative of the triatomic ambidentate ligands, and factors influencing the preferences for N- und S-bonding are summarized. Coordination chemistry of ß-dicarbonyl compounds is a highlight of this book. Acetylacetone, one of the most familiar Werner ligands, is shown to favor -carbon and n-allylic bonding in many instances. Its versatile behaviour in changing coordination modes is revealed.

Reactions of Coordinated Ligands

Reactions of Coordinated Ligands
Author: P.S. Braterman
Publisher: Springer
Total Pages: 1064
Release: 2011-11-10
Genre: Science
ISBN: 9781461290001

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This book is aimed at graduate students and research workers in aU branches of ohemistry, who wish to gain insight into what continues'to be one of the fastest growing areas of the subject. Aonding to a metal center may stabilize a ligand towards some reagents, activate it towards others, or modify its chemical behavior in more subtle ways. AU these effects have their uses, and aU invite understanding in terms of mechanism. Thus mechanistic insight is linked to control of reaction pathways. The detailed working out of this relationship provides the central theme of the book. The effect of the metal may be electronic or steric, and may involve the energy or the entropy of activation. It may depend on changes induced in the initial state of the ligand, or on those that only arise further along the reaction pathway. It may involve one coordination site or several, and the effects may be more, or less, specific to the metal involved and more, or less, amenable to control through the other Jigands. These remarks apply equaUy strongly to the carbon-bound ligands which occupy the major part of this work, and to those attached by other atoms. Thus the reactions discussed here are relevant in such diverse areas as bulk homogeneous catalysis, stereoselective stoichiometric synthesis, and bioinorganic chemistry.

Synthesis and Coordination Chemistry of Multidentate Ligands Based on Nitrogen-containing Heterocyclic Phenanthridine Moieties

Synthesis and Coordination Chemistry of Multidentate Ligands Based on Nitrogen-containing Heterocyclic Phenanthridine Moieties
Author: Rajarshi Mondal
Publisher:
Total Pages: 0
Release: 2020
Genre:
ISBN:

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This project explored the synthesis of bi-functional neutral donor ligands using pi-extended phenanthridine system which can stabilize the late transition metals. My interest would be the phenanthridine ring of 14 pi-electron polycyclic heteroaromatic system, which is the building block of my ligands and the properties of this extended aromatic system while binding with late transition metals and comparing with smaller congener quinoline precursor for understanding the effect of site dependent pi extension. The application and properties of designed metal complexes have been extensively studied. The study of using pi-extended phenanthridine as a ligand and its metal complexes would open a new window of opportunities. A synthetic route to bromo functionalization of benzo-fused N-heterocyclic phenanthridine, enabling the constructions of both phosphinophenanthridine and NHC carbene-phenanthridine have been devised, which are heterobifunctional Lewis base containing both phosphine/carbene and phenanthridine donors. The coordination chemistry for both phosphine/carbene ligands with ions of late first-row transition metals has been explored. 4-Bromophenanthridine was synthesized by Suzuki cross-coupling/condensation, 6-substitution was conducted by reaction between phenanthridinone and phosphine(V) oxyhalide. The installation of phosphine was directed by lithium-halogen exchange of 4-bromophenanthridine. The carbenes were placed by the reaction between 6-halophenanthridine and corresponding imidazole in high temperature. A series of halide bridge Cu complexes were synthesized using phosphino-phenanthridine ligand to check the effect of site selective pi-extension on emission property by comparing with smaller congener quinoline based Cu complexes. Further study leads to design of sterically encumbered phenanthridine for diminishing the excited state geometric orientation. A relative effect of counterion in solid-state emission lifetime has also been studied. A group of octahedral d8 metal complexes were synthesized by using both phosphine/carbene ligands to study the metal to ligand charge transfer and its lifetime. The potential of these complexes for use in the field of photosensitizer was also discussed. Phosphino ligand based Fe complexes have been synthesized and their use in the filed of hydrogenation catalysis has also been discussed.