[PDF] Synthesis And Characterization Of Helical Ligand Transition Metal Complexes eBook

Author : Tingting Liu
Publisher :
Page : pages
File Size : 49,30 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 : Otilia Costisor
Publisher : World Scientific
Page : 316 pages
File Size : 41,55 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.