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Book Multidentate Phosphino alkene Ligands and Their Late Transition Metal Complexes

Download or read book Multidentate Phosphino alkene Ligands and Their Late Transition Metal Complexes written by Amanda G. Jarvis and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The synthesis and characterisation of a new class of multidentate conformationally flexible phosphino-alkene ligands, called dbaPHOS (127) and monodbaPHOS (128), are described is this PhD thesis. The related phosphine sulphide ligands, namely dbaTHIOPHOS (137) and monodbaTHIOPHOS (149), have also been prepared. The coordination chemistry of the novel ligands was investigated with a variety of late-transition metals, including Cu, Rh, Pd and Pt. X-ray crystal structure determination of the complexes containing these ligands highlights the multiple coordination modes and versatility of each ligand system. The ability of the 1,4-dien-3-one backbone to adopt different conformational geometries around metal centers is of particular note. DbaPHOS (127) was found to act as a cis- and trans-chelating bisphosphine in both square planar PdII and PtII complexes. The 1,4-dien-3-one motif is hemilabile; exchange between coordinated and non-coordinated alkenes is observed in both the Pd0 complex, 167, and the related cationic CuI complex, 193. An investigation into the CuI complexes' activity in the cyclopropanation of styrene, as catalysts, showed that they are commensurate with other recently reported systems. In addition to the coordination chemistry of the novel ligand systems, some interesting findings emerged in the ligand synthesis and characterisation studies. For example, monodbaTHIOPHOS (149) undergoes an interesting solid-state [2+2] intramolecular cycloaddition transformation, giving cycloadduct, 206. Furthermore, 2-hydroperoxytetrahydrofuran was found to be an impurity in the microwave-assisted Horner-Wadsworth-Emmons reaction of 2-(diphenylthiophosphine)benzaldehyde (136) with 1,3-bis-(ethoxyphosphonato)-acetone (130) to give of dbaTHIOPHOS (137) and an unexpected THF insertion product, 138. The latter is explained by a side reaction involving the reduced compound, tetrahydrofuran-2-ol, derived from 2-hydroperoxytetrahydrofuran.

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

Download or read book Synthesis and Coordination Chemistry of Multidentate Ligands Based on Nitrogen containing Heterocyclic Phenanthridine Moieties written by Rajarshi Mondal and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Book Coordination Chemistry of Multidentate Ligands from a Multi component Reaction

Download or read book Coordination Chemistry of Multidentate Ligands from a Multi component Reaction written by Ann Almesaker and published by . This book was released on 2009 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Book Synthesis Structure and Reactivity of the Later Transition Metal Complexes Containing a Multidentate Phosphorus nitrogen Hybrid Ligand

Download or read book Synthesis Structure and Reactivity of the Later Transition Metal Complexes Containing a Multidentate Phosphorus nitrogen Hybrid Ligand written by Steven Michael Fornara Kennedy and published by . This book was released on 2000 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Transition Metal Complexes with P N Ligands and Silylenes Synthesis and Catalytic Studies

Download or read book Transition Metal Complexes with P N Ligands and Silylenes Synthesis and Catalytic Studies written by Eva Neumann and published by Cuvillier Verlag. This book was released on 2006-02-15 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: The term ligand [latin, ligare = bind] has its origin in coordination chemistry. It denotes a molecule that is able to bind to a metal center in most cases via one or several free electron pairs.[1] Ligands can be described by the number of electron-pair donor atoms as monodentate, bidentate, tridentate etc. ligands. The latter are also called chelating ligands [greek, chele = (crab’s) claw]. A typical classification of ligands is according to their electronic properties. They serve either as a σ-donating, σ-donating/π-accepting, or σ,π-donating/π-accepting ligands.[2] A more practical, often encountered approach is the classification of ligands according to their donor atoms, especially when larger molecules and molecules containing heteroatoms are regarded (compare 1.2). Coordination chemistry was already established in the 19th century. In 1893 Alfred Werner suggested an octahedral arrangement of ligands coordinated to a central metal ion for many compounds. This explained, for example, the appearance and reactivity of four different cobalt(III) complexes (Figure 1.1), when CoCl2 is dissolved in aqueous ammonia and then oxidized by air to the +3 oxidation state. The formulas of these complexes can be written as depicted in Figure 1.1. Werner’s work was rewarded with the Nobel prize in 1913.[3]

Book Synthesis of Multidentate Ligands and Their Coordination to Metals

Download or read book Synthesis of Multidentate Ligands and Their Coordination to Metals written by Steven Eric Twaddle and published by . This book was released on 1995 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Coordination Chemistry of Late Transition Metals with PCP Ligands

Download or read book Coordination Chemistry of Late Transition Metals with PCP Ligands written by Daniel Olsson and published by . This book was released on 2007 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Synthesis of Polydentate Ligands and TheFormation of Heterometallic and CircularHelicates

Download or read book Synthesis of Polydentate Ligands and TheFormation of Heterometallic and CircularHelicates written by Martina Whitehead and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Described herein, is the synthesis and coordination chemistry of seven novel ligands L1 - L7. These ligands form metallosupramolecular assemblies upon coordination of transition metal ions resulting in heterodi- and hetreotrimetallic double helicates and penta- and tetranuclear cyclic helicates. Described in Chapter 2 is a new class of ditopic segmental pyridyl-thiazole(py-tz) N-donor ligands L1 - L3. Reaction of L1 with ZnII ions results in the formation of a dinuclear double helicate [Zn2(L1)2]4+. Reaction of L2 with either ZnII or HgII results in the formation of the L2-containing dinuclear double helicates [Zn2(L2)2]4+ and [Hg2(L2)2]4+. However, reaction with both ZnII or HgII results in the sole formation of the heterodimetallic helicate [HgZn(L2)2]+. Both metal ions are 6-coordinate but the HgII ion is coordinated by the two py-tz-py units whereas the ZnII ion is coordinated by the py-py-tz domain. The reason that these isomeric sites have different preferences for each of the metal ions is due to the position of the thiazole unit within the terdentate domains, as in the central position the thiazole unit increases the?bite angle? of the donor unit making it more suitable for the larger HgII. Conversely the py-py-tz domain has a smaller bite angle and it more suited to the smaller ZnII ion. Reaction of L3 with ZnII, HgII and CuII results in the formation of a heterometallic trinuclear double helicate [HH-[HgCuZn(L3)2]5+. In a similar fashion to L2, the ZnII ion coordinated by the terdentate py-py-tz domain and the HgII coordinated by the py-tz-py domain. The central bipyridine unit coordinates the tetrahedral CuII ion resulting in the first reported example of a heterotrimetallic double helicate. Described in Chapter 4 is a potentially hexadentate N-donor ligand L4, which upon reaction with CdII results in the formation of a dinuclear double helicate [Cd2(L4)2]4+. In this structure the ligand partitions into two tridentate tz-py-py domains each of which coordinate a different metal ion. However, reaction of L4 with ZnII results in the formation of a pentanuclear circular helicate [Zn5(L4)5]10+, with all the five zinc ions adopting a octahedral coordination geometry arising from the coordination of the two tridentate tz-py-py domains from two different ligand strands. This difference in structure is attributed to unfavourable steric interactions which prevent the formation of [Zn2(L4)2]4+ but these unfavourable interactions are not present with the larger Cd2+ ion. Described in Chapter 5 are the potentially pentadentate and tetradentate ligands L5 and L6, respectively. The ligand L5 contains both a bidentate and tridentate binding site separated by a phenylene spacer unit. Reaction of L5 with CuII results in the formation of a pentanuclear circular helicate [Cu5(L5)5]10+. Each of the CuII ions adopts a 5-coordinate geometry formed by coordination of the bidentate domain of one ligand strand and the tridentate domain of a different ligand. As a result this gives a head-to-tail pentanuclear double helicate. Reaction of L6 and L4 (Chapter 4) with CuII results in the formation of a heteroleptic pentanuclear circular helicate [Cu5(L4)3(L6)2]10+. The cyclic array consists of five copper(II) ions, coordinated by three strands of L4 and two strands of L6. In this species four of the CuII adopt a 5- coordinate geometry arising from coordination of a tridentate domain from L4 and a bidentate domain from L6. The remaining copper ion is coordinated by two tridentate domains from L4 resulting in an octahedral coordination geometry. Described in Chapter 6 is the potentially hexadentate N-donor ligand L7 which comprises of two identical tridentate py-py-tz N3 binding domains separated by a pyrene unit. Reaction of L7 with ZnII results in the formation of a tetranuclear circular helicate [Zn4(L7)4]8+ with all four zinc metal ions adopting a six-coordinate geometry arising from the coordination of two tridentate pypy- tz units from two different ligand strands. The formation of this lower nuclearity species (e.g. tetranuclear rather than pentanuclear) is attributed to the p-stacking between the pyrene unit and the py-py-tz domain.

Book Rational Ligand Design for Potential Applications in Transition Metal Catalysis

Download or read book Rational Ligand Design for Potential Applications in Transition Metal Catalysis written by Sergey L. Sedinkin and published by . This book was released on 2011 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: Strategies to influence the steric and electronic properties of three classes of ligands were investigated. First, a compound class known as amino-dithiaphospholanes was studied. It is structurally related to phosphoramidites, which have been successfully applied in catalysis. The synthesis of amino-dithiaphospholanes was envisaged as an approach to electronically tuned phosphoramidites. General access to a variety of structurally modified amino-dithiaphospholanes from commercially available starting materials was developed. The electron donating properties of the new ligands were characterized by NMR. They were found to be more electron-donating than the corresponding phosphoramidites. The coordination chemistry of amino-dithiaphospholanes was investigated by synthesis of a series of iridium and rhodium complexes. Analysis of the physical data obtained for the complexes confirmed the increase in the electron density at the metal centers as a consequence of the increased basicity of the ligands. Second, a series of new, as well as known, phosphinooxazoline (PHOX) ligands was synthesized. A systematic study of structure-property relationships was performed with the PHOX ligands. It was shown that electronic tuning of the ligands is possible by varying the substituents on the phenyl ring. However, the tuning was seen to have unexpected, and often only minor influence on the electronic properties of the metal complexes. The efficiency of steric tuning was investigated by evaluation of X-ray structure analysis data of new iron PHOX complexes synthesized for the study. It was shown that the presence of substituents in the position a to the nitrogen atom of the oxazoline ring had the most profound impact on the geometries of the corresponding metal complexes. Finally, five new multidentate N, O donating ligands (L) were synthesized and characterized. Their coordination chemistry was investigated by preparation of new iron complexes mimicking naturally occurring non-heme enzymes. The general formulation [Fe(L)2](OTf)2, [Fe(L)(OTf)2] or [Fe(L)(OTf)](OTf) was established for the new complexes, and formation of only one isomer was confirmed for one of the complexes. The catalytic activity of the new compounds was demonstrated in the oxidation of activated methylene groups and alcohols to the corresponding ketones.

Book Proton responsive Pyridine based Ligands

Download or read book Proton responsive Pyridine based Ligands written by Sandra Yvette Boer and published by . This book was released on 2016 with total page 163 pages. Available in PDF, EPUB and Kindle. Book excerpt: Catalysts are in dispensable for society as they are applied in the majority of industrial processes. Catalysts can increase the rate at which a reaction proceeds, but can also selectively produce only one product, thereby preventing side reactions and the production of side products or waste, resulting in more efficient, atom-economical and environmentally benign processes. In homogeneous catalysis, the catalyst often consists of a transition metal that is surrounded by ligands. Reactive or proton-responsive ligands may be envisioned to operate in a synergistic way with the metal to facilitate a chemical process. This concept of metal-ligand cooperation (MLC) has gained a lot of interest over the past decade and is currently a rapidly expanding field of homogeneous catalysis. The research described in this thesis is focused on the development of new metal complexes bearing different proton-responsive ligand systems. More specifically, several bidentate and tridentate types of pyridine-based ligands are described, based on phosphinomethylpyridines, pyridones and pyrazoles. They all exhibit a cooperative character in their own specific way. The coordination to mainly 2nd row late-transition metals (Ru, Rh, and Pd) is successfully demonstrated, along with the behavior of their bifunctional character. Application in several catalytic transformations is studied, including various dehydrogenative coupling reactions and the intramolecular hydroamination of aminoalkenes and -alkynes.

Book Inorganic Nanoparticles

Download or read book Inorganic Nanoparticles written by Claudia Altavilla and published by CRC Press. This book was released on 2017-12-19 with total page 885 pages. Available in PDF, EPUB and Kindle. Book excerpt: Among the various nanomaterials, inorganic nanoparticles are extremely important in modern technologies. They can be easily and cheaply synthesized and mass produced, and for this reason, they can also be more readily integrated into applications. Inorganic Nanoparticles: Synthesis, Applications, and Perspectives presents an overview of these special materials and explores the myriad ways in which they are used. It addresses a wide range of topics, including: Application of nanoparticles in magnetic storage media Use of metal and oxide nanoparticles to improve performance of oxide thin films as conducting media in commercial gas and vapor sensors Advances in semiconductors for light-emitting devices and other areas related to the energy sector, such as solar energy and energy storage devices (fuel cells, rechargeable batteries, etc.) The expanding role of nanosized particles in the field of catalysis, art conservation, and biomedicine The book’s contributors address the growing global interest in the application of inorganic nanoparticles in various technological sectors. Discussing advances in materials, device fabrication, and large-scale production—all of which are urgently required to reduce global energy demands—they cover innovations in areas such as solid-state lighting, detailing how it still offers higher efficiency but higher costs, compared to conventional lighting. They also address the impact of nanotechnology in the biomedical field, focusing on topics such as quantum dots for bioimaging, nanoparticle-based cancer therapy, drug delivery, antibacterial agents, and more. Fills the informational gap on the wide range of applications for inorganic nanoparticles in areas including biomedicine, electronics, storage media, conservation of cultural heritage, optics, textiles, and cosmetics Assembling work from an array of experts at the top of their respective fields, this book delivers a useful analysis of the vast scope of existing and potential applications for inorganic nanoparticles. Versatile as either a professional research resource or textbook, this effective tool elucidates fundamentals and current advances associated with design, characterization, and application development of this promising and ever-evolving device.

Book Studies on the Synthesis of Main Group and Late Transition Element Frameworks

Download or read book Studies on the Synthesis of Main Group and Late Transition Element Frameworks written by Christian Samanamu and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal organic frameworks (MOFs) are metal-ligand compounds that extend into one, two or three dimensions via metal-ligand bonding that have found numerous technological applications, associated with their open pores and large internal surface area. The work developed in this doctoral thesis consists in the study of methodologies and systematic development of ligands or organic spacers for the synthesis of novel metal organic frameworks. An introduction to the chemistry, structural features and diverse applications of metal organic frameworks is provided in Chapter 1. The following chapter, chapter 2 involves the synthesis of gallium, indium and thallium metal organic frameworks using pyrazine, and pyrazine-2-carboxylic acid as organic spacers. The change in the pore size of the synthesized frameworks was studied in correlation with the atomic radii of the selected triel elements. Chapter 3 describes the work with the flexible, multidentate heteroelemental dipodal ligands: bis(2-pyridylthio)methane, bis(2-pyrimidylthio)methane and bipyrimidyldisulfide. These ligands were reacted with a series of copper halides or pseudo halides for the isolation of cubane clusters and polymers depending on the flexibility of the selected ligands, the stereochemical requirements of the metal center and the preferred coordination modes of the corresponding halide or pseudo halide. The fourth chapter deals with the use of 2-pyridinephosphonic acid (2PyPOH2), 4-pyridinephosphonic acid (4PyPOH2) and 4-pyridinemethylphosphonic acid (4PyCH2PO3H2) for the synthesis of aluminum and gallium phosphonate cages. The isolation of these cages was achieved under careful control of the hydrolytic conditions of the corresponding reaction media. Chapter 5, details the results of the studies with the ligand aminomethylphosphonic acid (ampa) for the construction of MOFs. The reaction of ampa with salts of Zn, Cd, Hg, Pb, Ag, Cu and Pb afforded new metal-phosphonate polymers with unique structural features and includes the synthesis of a bimetallic MOF containing Ag and Cu. Finally, chapter 6 analyzes the ligand 5-pyrimidyl phosphonic acid (5-PymPO3H2) in the synthesis of homo and heteroelemental MOFs based on its possession of a phosphonate moiety for coordination and two heterocyclic nitrogen atoms at the opposite end to the PO3H2 to promote multi-site coordination. As a consequence it was possible to synthesize six coordination polymers, including a two dimensional, Cu/Ag polymer. All of the MOFs obtained throughout these studies have been characterized by X-ray crystallography along with other spectroscopic techniques, including NMR, IR, UV/Vis, and MS.

Book Metallocenes in Regio and Stereoselective Synthesis

Download or read book Metallocenes in Regio and Stereoselective Synthesis written by Marko Hapke and published by Springer Nature. This book was released on with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book The Synthesis and Structural Characterisation of the Lanthanide and Transition Metal Coordination Polymers Formed with Novel Multidentate Ligands

Download or read book The Synthesis and Structural Characterisation of the Lanthanide and Transition Metal Coordination Polymers Formed with Novel Multidentate Ligands written by D. A. Grachvogel and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: