[PDF] Helical Transition Metal Complexes eBook

Author : Tingting Liu
Publisher :
Page : pages
File Size : 49,57 MB
Release : 2011
Category :
ISBN :

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A series of chiral titanium and manganese complexes with helix-directing salen ligands have been prepared, characterized and studied. Their structures displayed as a chiral helical motif as expected. And it was also found that all M(salen) units were exclusively M-helimeric in the solid state, except Ti(cyclohexyl-benz[a]anthryl) as P-helix. This may be due to the energy difference between P and M helice, which enables crystal packing forces to control and drive the molecular structure. This is also in agreement with the previous computational studies that the M configuration predominates in THF solution. All metal centers adopt a cis-[beta] octahedral geometry except in Mn(binapthyl-phenanthryl-salen). Most of M(salen) complexes in this work afforded [mu]-oxo dinuclear helicates, instead of the expected monohelicate, except Mn(binapthyl-phenanthryl-salen), which is bridged by a third salen ligand. The titanium salt affected the complex solution behavior. In the presence of Cl[superscript]-, only mononuclear species was found by ESI-MS, while both di- and mononuclear species was found in MeOH in the presence of--O[superscript]iPr. The NMR spectra of Ti(salen) indicated one major species with cis-[beta] geometry exist in most solution, which could be monomer or dimer, except Ti(binapthyl-salen). No counterions have been found in the solid state of Mn(salen) complexes in this work, but they affected the ligand decomposition in the solution in Mn(binapthyl-phenanthryl-salen). The Mn(salen) complexes could effectively and enatioselectively catalyze the asymmetric epoxidation of somoe trans, cis and terminal olefin, and various oxidants were employed.

Author : Sanmitra Barman
Publisher :
Page : pages
File Size : 37,46 MB
Release : 2010
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Stepped helical salen complexes with vanadium as the central metal were synthesized and characterized. The helicity in these complexes arise from the fused phenyl rings (phenanthryl and benz[a]anthryl) as sidearms, whereas the chirality arises from the chiral cyclohexyl diamine or binaphthyl diamine backbones. These complexes showed good yields and moderate enantioselectivity in asymmetric sulfoxidation reactions with methylphenyl sulfide as the substrate and H2O2 or cumene hydroperoxide as the oxidants. To further improve the closed nature of these complexes with a tetradentate salen ligand, we synthesized and characterized vanadium complexes with tridentate (S)-NOBIN backbone Schiff base ligands with phenanthryl and benz[a]anthryl as the sidearms. After initial catalytic study, we concluded that these catalysts are too open in nature to impose face selection during asymmetric induction. We also synthesized and characterized vanadium and titanium salan complexes. These complexes can adopt [Beta]-cis geometry, thereby making the complex "chiral at metal" and they are known for better catalysts in terms of asymmetric induction than their unreduced counterparts. However, these complexes showed better catalytic activity than their unreduced counterparts in sulfoxidation reactions with methylphenyl sulfide as the substrate and H2O2 or cumene hydroperoxide as the oxidants. We also put an effort to synthesize mixed salen complexes with vanadium as the central metal. These complexes have two different sidearms attached to one backbone unit. However, our method did not work well to produce pure mixed salen ligands. The catalysis results for mixed salen vanadium complexes are also comparable to the unreduced vanadyl salen complexes. Lastly, we synthesized and characterized new helical titanium Schiff base complexes with (S)-NOBIN backbone and phenanthryl and benz[a]anthryl sidearms. Single crystal studies showed that these complexes exist in the M helical conformation in the solid state. These complexes showed moderate activity in asymmetric aldol addition reactions between 2-methoxy propene and different aldehydes.

Author : N. Farrell
Publisher : Springer Science & Business Media
Page : 304 pages
File Size : 31,90 MB
Release : 2012-12-06
Category : Science
ISBN : 9401175683

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When this book was first conceived as a project the expanding interest in the clinical use of platinum and gold complexes made a survey of the relevant biological properties of metal complexes timely and appropriate. This timeliness has not diminished during the gestation and final publica tion of the manuscript. The introduction contains an explanation of the layout and approach to the book, which I wrote as an overall survey of the wide variety of biological properties of metal complexes. Hopefully, the reader will see the parallels in mechanisms and behavior, even in different organisms. The writing was considerably helped by the enthusiasm and confidence (totally unearned on my part) in the project of Professor Brian James and lowe him my special thanks. I also owe a great debt of gratitude to my colleagues, and especially to Eucler Paniago, of the Universidade Federal de Minas Gerais, for their comprehension and for the initial leave of absence which allowed me to begin the project. To those who read some or all of the manuscript and made suggestions, Bernhard Lippert, Kirsten Skov, and Tom Tritton, as well as the editor's reviewer I am also grateful. As usual, the final responsibility for errors or otherwise rests with the author.

Author : John L Burmeister
Publisher : World Scientific
Page : 654 pages
File Size : 38,39 MB
Release : 2003-10-14
Category : Science
ISBN : 9814488003

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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 : Remi Chauvin
Publisher : Springer Science & Business Media
Page : 260 pages
File Size : 24,46 MB
Release : 2010-01-12
Category : Science
ISBN : 3642047211

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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 : Otilia Costisor
Publisher : World Scientific
Page : 316 pages
File Size : 36,9 MB
Release : 2004
Category : Science
ISBN : 9789812794819

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This book surveys the relatively new area of the synthesis of organic ligands when metal ions act as a template. In the last fifty years this field has undergone an explosive development, marked by a great amount of literature. The material in the book has been arranged according to the type of chemical reaction involved. In this frame, the basic principles of metal template reactions and the shape of the molecules are considered. Designed to satisfy the demands of students, young researchers doing their PhDs, and those working in the field of coordination chemistry, the book details the role of the metal ions and the specific properties of the formed complexes. Metal Mediated Template Synthesis of Ligands offers a comprehensive analysis with wide-ranging references and provides an extensive overview of research on metal-directed organic ligands over the past five decades. Contents: The Template Effect; Alkylation Reactions; Schiff Condensation; Mannich Condensation; Self Condensation of Nitriles; Self-Assembled Systems. Readership: Upper level undergraduates, graduate students, academics, researchers industrialists in inorganic, solid-state, supramolecular and organic chemistry.

Author : Vivian W. W. Yam
Publisher : Springer
Page : 266 pages
File Size : 50,60 MB
Release : 2007-05-30
Category : Science
ISBN : 3540368108

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With contributions by numerous experts