Synthesis and Coordination Chemistry of Multidentate Ligands Based on Nitrogen-containing Heterocyclic Phenanthridine Moieties PDF Download
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Author: Rajarshi Mondal
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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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.
Author: Rajarshi Mondal
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
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.
Author: Bryan Kenneth Shaw
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Nate C. Schultheiss
Publisher:
ISBN:
Category : Ligands
Languages : en
Pages : 254
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Author: NILOOFAR. ZARRABI
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Jelena Jenter
Publisher: Cuvillier Verlag
ISBN: 3736933428
Category : Science
Languages : en
Pages : 134
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Book Description
Bis(phosphinimino)methanide rare earth metal bisborohydrides, as illustrated in Scheme I, were successfully synthesized by salt metathesis reactions of [K{CH(PPh2NSiMe3)2}] with [Ln(BH4)3(THF)n] (Ln = Sc (n = 2); Ln = La, Nd, Lu (n = 3)) or in the case of yttrium by the reaction of [{(Me3SiNPPh2)2CH}YCl2]2 with NaBH4. Interestingly, the BH4- anions are ?3-coordinated in the solid state structures of 3, 4, 6 and 7, while for the scandium complex 5 two different conformational polymorphs were identified, in which either both BH4- groups are ?3-coordinated or one BH4- anion shows an ?2-coordination mode. Furthermore, complexes 3, 6 and 7 showed high activities in the ring-opening polymerization (ROP) of e-caprolactone (CL). At 0 °C, the molar mass distribution reached the narrowest values ever obtained for the ROP of CL initiated by a rare earth metal borohydride species. In collaboration with N. Meyer, rare earth metal chlorides and borohydrides of the 2,5-bis{N-(2,6-diisopropylphenyl)iminomethyl}pyrrolyl ligand were synthesized, as shown in Scheme II. The reaction of [(DIP2pyr)K] (10) with anhydrous neodymium trichloride afforded [(DIP2pyr)NdCl2(THF)]2 (12) which is dimeric in the solid state. Excitingly, the reaction of [(DIP2pyr)K] (10) with [Ln(BH4)3(THF)n] (Ln = Sc (n = 2); Ln = La, Nd, Lu (n = 3)) depends on the ionic radii of the center metals. For the larger rare earth metals lanthanum and neodymium, the expected products [(DIP2pyr)Ln(BH4)2(THF)2] (Ln = La (13), Nd (14)) were obtained; while for the smaller rare earth metals scandium and lutetium, an unusual redox reaction of a BH4- anion with one of the Schiff-base functions of the ligand was observed and the products [{DIP2pyr*-BH3}Ln(BH4)(THF)2] (Ln = Sc (15), Lu (16)) were formed (Scheme II). Moreover, the two neodymium containing complexes 12 and 14 were investigated as Ziegler-Natta catalysts for the polymerization of 1,3-butadiene to form poly-cis-1,4-butadiene, by using various cocatalyst mixtures. Very high activities and good selectivities were observed for 12. The 2,5-bis{N-(2,6-diisopropylphenyl)iminomethyl}pyrrolyl ligand was successfully introduced into the coordination chemistry of the divalent lanthanides and the alkaline earth metals. As shown in Scheme III, salt metathesis reactions of [(DIP2pyr)K] (10) with either anhydrous lanthanide diiodides or alkaline earth metal diiodides afforded the corresponding heteroleptic iodo complexes [(DIP2pyr)LnI(THF)3] (Ln = Sm (19), Eu (20), Yb (21)) or [(DIP2pyr)MI(THF)n] (M = Ca (24), Sr (22) (n = 3); Ba (23) (n = 4)). Surprisingly, all complexes 19-24 are monomeric in the solid state, independently from the ionic radii of their center metals. Instead of forming dimers, the coordination sphere of each metal center is satisfied by additionally coordinated THF molecules, which is a very rare structural motif in the chemistry of the larger divalent lanthanides and alkaline earth metals. While the (DIP2pyr)- ligands in 19-23 are ?3-coordinated in the solid state, for the calcium complex 24 an ?2-coordination mode was observed (Scheme III). Interestingly, the calcium complex 24 and the analogous ytterbium compound 21 show different structures in the solid state. In order to obtain catalytically active species, [(DIP2pyr)M{N(SiMe3)2}(THF)2] (M = Ca (25), Sr (26)) were prepared by the reaction of [(DIP2pyr)MI(THF)3] (M = Ca (24), Sr (22)) with [K{N(SiMe3)2}] (Scheme IV). Compounds 25 and 26 were investigated for the intramolecular hydroamination of aminoalkenes and one aminoalkyne. Unfortunately, both catalysts exhibit a limited reaction scope, caused by the formation of undesired side products by alkene isomerization and imine-enamine tautomerism. However, both compounds are active catalysts and show high yields and short reaction times. The highest activities were observed for the calcium complex 25 and can be compared to the results obtained with the ß-diketiminato calcium amide [{(DIPNC(Me))2CH}Ca{N(SiMe3)2}(THF)] as a catalyst. Finally, imidazolin-2-imide and cyclopentadienyl-imidazolin-2-imine rare earth metal alkyl complexes, synthesized by M. Tamm et al., were investigated for the intramolecular hydroamination of non-activated aminoalkenes and one aminoalkyne. Both compounds showed high selectivities and activities, and although they cannot compete with the metallocene analogues, the imidazolin-2-imide complexes are new and interesting examples for catalytically active post-metallocenes.
Author: Jose M Lassaletta
Publisher: World Scientific
ISBN: 1786346478
Category : Science
Languages : en
Pages : 676
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Book Description
Chapter contribution from Ben Feringa, Nobel Laureate in Chemistry 2016.Atropisomerism and Axial Chirality provides a global survey of the chemistry of axially chiral compounds including biaryls, heterobiaryls, non-biaryl atropisomers, allenes and spyrocyclic derivatives. From the perspective of a synthetic organic chemist, this book provides a unique compilation of the available methodologies for their synthesis, with emphasis on the most efficient and modern strategies, a review of the huge amount of practical applications in the field of asymmetric catalysis, either as transition metal ligands or as organocatalysts, and an overview of their occurrence as bioactive compounds and natural products.The first of its kind, this book serves as a general introduction and a practical reference to advanced chemistry students and researchers, while also offering creative ideas for further developments in the field.
Author: Eusebio Juaristi
Publisher: CRC Press
ISBN: 9780849389412
Category : Science
Languages : en
Pages : 248
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Book Description
This book provides a comprehensive review of the structural, conformational, and chemical manifestations of the anomeric effect. In order to present a cogent discussion of this most fundamental and relevant phenomenon, three chapters examine our present understanding of the origin of this conformational effect, based upon a wealth of theoretical and physical data. Equally important, however, are three additional chapters that deal with the general consequences of the stereoelectronic interactions that are associated with the basis of the anomeric effect. The remainder of the book is devoted to new areas of development in the topic-such as differentiation of the endo and exo anomeric interactions, specific analysis of the enthalpic component of anomeric effects, critical evaluation of the kinetics and reverse anomeric effects, discovery of a new substantial effect in second- and lower-row anomeric segments, and others.
Author: Jonathan L Sessler
Publisher: Royal Society of Chemistry
ISBN: 1847552471
Category : Science
Languages : en
Pages : 431
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Book Description
Anion recognition plays a critical role in a range of biological processes, and a variety of receptors and carriers can be found throughout the natural world. Chemists working in the area of supramolecular chemistry have created a range of anion receptors, drawing inspiration from nature as well as their own inventive processes. This book traces the origins of anion recognition chemistry as a unique sub-field in supramolecular chemistry while illustrating the basic approaches currently being used to effect receptor design. The combination of biological overview and summary of current synthetic approaches provides a coverage that is both comprehensive and comprehensible. First, the authors detail the key design motifs that have been used to generate synthetic receptors and which are likely to provide the basis for further developments. They also highlight briefly some of the features that are present in naturally occurring anion recognition and transport systems and summarise the applications of anion recognition chemistry. Providing as it does a detailed review for practitioners in the field and a concise introduction to the topic for newcomers, Anion Receptor Chemistry reflects the current state of the art. Fully referenced and illustrated in colour, it is a welcome addition to the literature.
Author: Silvia Diez-Gonzalez
Publisher: Royal Society of Chemistry
ISBN: 1782626816
Category : Science
Languages : en
Pages : 637
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Book Description
In less than 20 years N-heterocyclic carbenes (NHCs) have become well-established ancillary ligands for the preparation of transition metal-based catalysts. This is mainly due to the fact that NHCs tend to bind strongly to metal centres, avoiding the need of excess ligand in catalytic reactions. Also, NHC‒metal complexes are often insensitive to air and moisture, and have proven remarkably resistant to oxidation. This book showcases the wide variety of applications of NHCs in different chemistry fields beyond being simple phosphine mimics. This second edition has been updated throughout, and now includes a new chapter on NHC‒main group element complexes. It covers the synthesis of NHC ligands and their corresponding metal complexes, as well as their bonding and stereoelectronic properties and applications in catalysis. This is complemented by related topics such as organocatalysis and biologically active complexes. Written for organic and inorganic chemists, this book is ideal for postgraduates, researchers and industrialists.
Author: Andre S. Merbach
Publisher: John Wiley & Sons
ISBN: 1118503678
Category : Science
Languages : en
Pages : 514
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Book Description
Magnetic Resonance Imaging (MRI) is one of the most important tools in clinical diagnostics and biomedical research. The number of MRI scanners operating around the world is estimated to be approximately 20,000, and the development of contrast agents, currently used in about a third of the 50 million clinical MRI examinations performed every year, has largely contributed to this significant achievement. This completely revised and extended second edition: Includes new chapters on targeted, responsive, PARACEST and nanoparticle MRI contrast agents. Covers the basic chemistries, MR physics and the most important techniques used by chemists in the characterization of MRI agents from every angle from synthesis to safety considerations. Is written for all of those involved in the development and application of contrast agents in MRI. Presented in colour, it provides readers with true representation and easy interpretation of the images. A word from the Authors: Twelve years after the first edition published, we are convinced that the chemistry of MRI agents has a bright future. By assembling all important information on the design principles and functioning of magnetic resonance imaging probes, this book intends to be a useful tool for both experts and newcomers in the field. We hope that it helps inspire further work in order to create more efficient and specific imaging probes that will allow materializing the dream of seeing even deeper and better inside the living organisms. Reviews of the First Edition: "...attempts, for the first time, to review the whole spectrum of involved chemical disciplines in this technique..."—Journal of the American Chemical Society "...well balanced in its scope and attention to detail...a valuable addition to the library of MR scientists..."—NMR in Biomedicine
