Synthesis and Coordination Chemistry of Polypyridyl Amide Ligands

Synthesis and Coordination Chemistry of Polypyridyl Amide Ligands
Author: Maisara Abdul Kadir
Publisher:
Total Pages: 331
Release: 2012
Genre: Coordination compounds
ISBN:
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This thesis provides an account of the synthesis and study of fifteen amide-containing polypyridyl ligands, eleven of which are new compounds. These ligands all possess at least one amide moiety, potentially capable of anion binding and one or more pendant pyridyl donor groups as the metal coordinating sites. A further evolution over previously reported compounds is that a majority of the amide compounds incorporate a pre-organised amide component that will constitute the anion binding region. The alkyl and phenyl spacers were utilised to confer flexibility to these compounds and to extend the spacing between the anion binding moiety and the pendant metal complexing groups. The compounds investigated in this work are divided into three categories; (i) unsymmetrical monoamide ligands that possess one amide functional group, one ester protected carboxylate and one external donor pyridyl moiety; (ii) symmetrical flexible amide ligands that possess two or more internal amide groups and two external pyridyl metal coordinating sites, and; (iii) symmetrical amide bridging ligands that incorporate two di-2-pyridylmethylamine chelating motifs. The coordination chemistry and metallo-supramolecular chemistry of these ligands was investigated with a range of late transition metals including cadmium(II), copper(II), cobalt(II), silver(I), zinc(II) and palladium(II). Palladium(II) precursors, with a selection of monodentate or bidentate chelating ancillary blocking ligands, were utilised to form discrete mono- and dinuclear assemblies with a view to investigating anion complexation in solution. Other transition metal precursors were studied with a focus on the synthesis of coordination polymers that display anion coordinating pockets.

Scorpionates: The Coordination Chemistry Of Polypyrazolylborate Ligands

Scorpionates: The Coordination Chemistry Of Polypyrazolylborate Ligands
Author: Swiatoslaw Trofimenko
Publisher: World Scientific
Total Pages: 294
Release: 1999-08-16
Genre: Science
ISBN: 1783261994
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This book deals with polypyrazolylborates (scorpionates), a class of ligands known since 1966, but becoming rapidly popular with inorganic, organometallic and coordination chemists since 1986, because of their versatility and user-friendliness. They can be readily modified sterically and electronically through appropriate substitution on the pyrazole ring and on boron, and have led to a number of firsts in coordination chemistry (first stable CuCO complex, first monomeric MgR complex, and many other such firsts). Their denticity can range from two to four, their “Bite” can be adjusted, and additional coordinating sites can be added to the pyrazolyl rings. Over 170 different scorpionate ligands are known today, and some are published for the first time in this book.The author, Swiatoslaw Trofimenko, discovered and developed this ligand system and has written several reviews on the subject. The book is intended as a reference work, placing at the researcher's command practically all of the over 1500 references on the subject up, and into 1999, organized both according to the ligand type and according to the metal or metalloid being coordinated. It acquaints the reader with the special features of this ligand system and permits an assessment of what has been done in a given sub-area, and of which areas remain relatively unexplored. It presents procedures for ligand synthesis, and also covers their use in catalysis and in the modelling of biologically active substances.

Development of Polypyridyl Pyrazolate-bridging Dinucleating Ligands Containing Hydrogen-bond Donors

Development of Polypyridyl Pyrazolate-bridging Dinucleating Ligands Containing Hydrogen-bond Donors
Author: Kwanyi Ng
Publisher:
Total Pages: 171
Release: 2012
Genre:
ISBN: 9781267247643
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The first chapter of this dissertation describes the importance of hydrogen bonding (H-bonding) within the secondary coordination sphere of metal complexes. Particular emphasis is given to the correlations between the structures of metalloenzyme actives and their functions. Classical examples of synthetic metal complexes, which are designed to mimic some of the features of metalloenzyme active sites, are also reviewed. The detection of reactive intermediates in the mononuclear systems has inspired the development of the dinucleating ligands, which is the cornerstone of the work described in this dissertation. In Chapter 2, the synthesis of a (carboxyamido)pyridinepyrazolate (H5bppap) dinucleating ligand is described. Bimetallic iron and cobalt complexes of H5bppap ([MII2H2bppap]+) showed structural differences in both their primary and secondary coordination spheres. The [CoII2H2bppap]+ is 5,5-corodinate while [FeII2H2bppap]+ is 5,6-coordinate. The binding of small molecules into the preorganized ligand cavity is verified by the hydration of [FeII2H2bppap]+ and [CoII2H2bppap]+, leading to the formation of complexes [{CoII(OH)}CoIIH3bppap]+ and [{FeII(OH)}FeIIH3bppap]+, in which only one of the metal centers has a terminal hydroxo ligand. Chapter 3 will present the synthesis and characterization of a dimanganese(II) complex, [MnII2H2bppap]+. The coordination chemistry of the dimanganese(II) analog of H5bppap is considerably different from its iron and cobalt counterparts. The insertion of external ligands into [MnII2H2bppap]+ with simultaneous protonation of the ligand backbone led to the isolation of a series of seven-coordinate dinuclear MnII species, [MnII2([mu]61549;-X)H4bppap]2+. Chapter 4 illustrates the design and synthesis of a dinucleating ligand, 3,5-Bis[bis(N-6-neopentylamino-2-pyridylmethyl)aminomethyl]-1H-pyrazole (H5bnppap). The syntheses and characterization of the corresponding dinuclear bis(hydroxo) complexes, [MII2H4bnppap(OH)2]+ are discussed. These complexes feature the rare terminal bis(OH) moiety within one molecular unit with the MII-OH units are positioned in a syn-configuration, placing the hydroxo ligands in close proximity (ca. 3 Å apart), which may be a prerequisite for water oxidation. The second part of the chapter describes the hydrolytic studies utilizing [CoII2H4bnppap(OH)2]+. Both [CoII2H4bnppap(OH)2]+ and [{CoII (OH)}MIIH3bppap]+ are able to hydrolyze carbon dioxide to give carbonate-bridged complexes. However, only [CoII2H4bnppap(OH)2]+ is able to hydrolyze triphenylborane to triphenylborate. These results indicate that control of the number of hydroxide ligands within the bimetallic cavity could be used as a strategy to regulate activity of metal-hydroxo complexes.