Synthesis and Characterization of Dinuclear Iron Macrocyclic Complexes as Models for Diiron Proteins PDF Download
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Author: Zheng Wang
Publisher:
ISBN:
Category :
Languages : en
Pages : 302
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Author: Zheng Wang
Publisher:
ISBN:
Category :
Languages : en
Pages : 302
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Author: Mikael Antoine Minier
Publisher:
ISBN:
Category :
Languages : en
Pages : 276
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Chapter 1: Understanding the Utility of Hydrogen Bonding Donors in the Secondary Coordination Sphere of Non-heme Metal Complexes Chapter 1 is a mini-review that covers systematic studies on the effect of hydrogen bonding donors on the properties of metal complexes. Generalizing across different metals studied in biomimetic chemistry, the review allows for the comparison between different systems and generalizations are drawn about the effects of secondary coordination sphere hydrogen bond donors. Chapter 2: 19F NMR Study of Ligand Dynamics in Carboxylate-Bridged Diiron(II) Complexes Supported by a Macrocyclic Ligand A series of asymmetrically carboxylate-bridged diiron(II) complexes featuring fluorine atoms as NMR spectroscopic probes, [chemical formula ...] (10), [chemical formula ...] (11), and [chemical formula ...] (12) were prepared and characterized by X-ray crystallography, M6ssbauer spectroscopy, and VT 19F NMR spectroscopy. These complexes are part of a rare family of syn-N diiron(II) complexes, [chemical formula ...], that are structurally very similar to the active site of MMOHred. Solution characterization of these complexes demonstrates that they undergo intramolecular carboxylate rearrangements, or carboxylate shifts, a dynamic feature relevant to the reactivity of the diiron centers in bacterial multicomponent monooxygenases. Chapter 3: Structural Characterization of Carboxylate-Bridged and Hydroxo-Bridged Dizinc(II) Complexes Supported by a Macrocyclic Ligand Using a syn-N dinucleating macrocyclic ligand, H2PIM, a doubly carboxylate-bridged dizinc(II) complex, [chemical formula ...] (6) was prepared. In crystallizations of 6, two pseudoisomorphs of [chemical formula ...] (7) were discovered. On route to the synthesis of 6, a zinc complex, [chemical formula ...] (4) was prepared and the product upon reaction with air, [chemical formula ...] (5), was crystallized. Chapter 4: Secondary Coordination Sphere Modulation of Redox Potentials in Azide-Bridged Diiron(II) Complexes Observation that the H2PIM macrocyclic ligand provides an extra binding site for the binding of small molecules adjacent to corresponding diiron(II) complexes inspired the appendage of a secondary coordination sphere hydroxyl group to the ligand. The new ligand, H3PIM2, models not only the primary coordination sphere of the diiron sites of methane monooxygenase and toluene/o-xylene monooxygenase, but also that of a local threonine in the secondary coordination sphere. This chapter explores the differences between the PIM system and PIM2 system through the electrochemistry of the azido diiron(II) derviatives. Chapter 5: Synthesis and Characterization of a Linear Dinitrosyl-Triiron Complex Nitric oxide is released during the immune response by the host during bacterial infection. To counteract this response, bacteria have evolved nitric oxide reductases to convert NO to N2O. Some of these nitric oxide reductases contain a flavodiiron active site that have bridging carboxylates and hydroxides. Only a handful of synthetic complexes currently exist as models for the protein reactivity. Here we report the reaction of [chemical formula ...] (4) with NO(g) and Ph3CSNO to prepare the dinitrosyl-triiron complex [chemical formula ...] (5). The reaction was monitored by U V-Vis and ReactIR spectroscopy and compound 5 was characterized by X-ray crystallography, 5 7Fe M6ssbauer spectroscopy, Evans' method, and FTIR spectroscopy. The IR spectrum of compound 5 compares favorably to experimental spectroscopic data obtained for the proposed mononitrosylated intermediate of the protein. Chapter 6: Doubly and Triply Carboxylate Bridged Bis(ethylzinc) Complexes and Formation of the ([mu]-Oxo)tetrazinc Carboxylate [chemical formula ...] Ethylzinc 2,6-bis(p-tolyl)benzoate converts between two forms in solution. Through NMR spectroscopic techniques and X-ray crystallography, the species in equilibrium were identified as [chemical formula ...] (1), [chemical formula ...] (2), and diethyl zinc [chemical formula ...]. The equilibrium provides a model for understanding the speciation between doubly and triply m-terphenylcarboxylate-bridged diiron(II) and mononuclear iron(II) complexes. Evidence is presented for the occurrence of coordinatively unsaturated trigonal zinc species in solution. Both 1 and 2 decompose in air to form the T-symmetric oxozinc carboxylate, [chemical formula ...] (3). Appendix A: Synthesis and Characterization of Mononuclear, Pseudotetrahedral Cobalt(III) Compounds The preparation and characterization of two mononuclear cobalt(III) tropocoronand complexes, [chemical formula ...] and [chemical formula ...], are reported. The cobalt(III) centers exist in rare pseudotetrahedral conformations, with twist angles of 65° and 74° for the [Co(TC-5,5]+ and [Co(TC-6,6)]+ species, respectively. Structural and electrochemical characteristics are compared with those of newly synthesized [chemical formula ...] and [chemical formula ...] analogs. The spin state of the pseudotetrahedral [chemical formula ...] was determined to be S = 2, a change in spin state from the value of S = 1 that occurs in the square-planar and distorted square-planar complexes, [chemical formula ...] and [chemical formula ...], respectively. Appendix B: Synthetic Strategies toward Sterically Demanding Macrocyclic Ligands In order to prevent the formation of iron complexes of nuclearity higher than 2, a picket-fence macrocyclic ligand, H2tipp4PIM was designed. This chapter discusses the progress towards the synthesis of this ligand as well as design strategies.
Author: Miroslav Rapta
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Category : Copper compounds
Languages : en
Pages : 790
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Author: Philip Hayden Merrell
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Category : Iron
Languages : en
Pages : 400
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Author: Sungho Yoon
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ISBN:
Category :
Languages : en
Pages : 301
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(Cont.) tetrairon(II) cubane complex was identified and structurally characterized. Chapter 4: Synthesis and Characterization of [Fe2 ... CR)]3 and [Fe2 ... CR)]3+ Complexes with Carboxylate-Rich Metal Coordination Environment as Models for Diiron Centers in Oxygen-Dependent Non-Heme Enzymes. Utilizing hydrogen bonding interactions and sterically bulky carboxylates, synthetic routes were developed to prepare the mononuclear iron(II) complexes with the vacant coordination sites for O2 binding. Reactions of such complexes with O2 resulted in rare asymmetric complexes having an [Fe2 ... CR)]3+ or [Fe2 ... CR)]3+ unit. These diiron(III) complexes with carboxylate-rich metal coordination environments reproduce the diiron(III) cores housed in four-helix bundles found in nature. Compound 3, which replicates the [Fe2 ... CR)] core of sMMOH[ox], shares several physical properties with the enzyme, electronic transitions, Mossbauer spectra, and magnetic exchange interactions. On the other hand, the structure of 4, ([mu]-oxo)([mu]-carboxylato)diiron(III) complex, mimics the diiron(III) sites of RNR-R2. The electronic and Mbssbauer spectral transitions of 4 are typical of diiron(III) complexes with an Fe-O-Fe moiety. Magnetic exchange coupling interaction between the two iron atoms is within the expected range for oxo-bridged diiron(III) sites. These results demonstrate how the diiron(III) structures in different metalloproteins, namely, the [mu]-oxo cores of RNR-R2 and the [mu]-dihydroxo unit in MMOH, can be replicated by subtle changes in ligand composition ...
Author: Kimberly L. Kostka
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Category :
Languages : en
Pages : 0
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Author: Mary Clare Rakowski
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Category : Complex compounds
Languages : en
Pages : 512
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Author: Jane Kuzelka
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ISBN:
Category :
Languages : en
Pages : 212
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Chapter 1. Bio-Inspired Reactions of Diiron Centers with Dioxygen A variety of biological systems employ carboxylate-bridged diiron centers to achieve substrate oxidation using dioxygen, and numerous small molecule model compounds have been synthesized in order to mimic this chemistry in the absence of a protein scaffold. In this introductory chapter, a brief overview is presented of ligand systems that have been used to prepare diiron complexes, and the subsequent oxidation chemistry of these systems is outlined. Chapter 2. Carboxylate, Phosphodiester, and Hydroxide-Bridged Diiron(II) Complexes with a Sterically Hindered Phthalazine Ligand The synthesis and crystallographic characterization of a series of diiron(II) complexes with a sterically hindered bridging phthalazine ligand are presented. The compounds [Fe2(Ph4bdptz)([mu]-O2CR)2]2+ (R = CH3 (3); C2H5 (4); CH2Ph (5); t-C4H9 (6)), [Fe2(Ph4bdptz)([mu]-O2P(OPh)2)2]2+ (7), and [Fe2(Ph4bdptz) ([mu]-OH)(MeCN)2]3+ (8) were prepared as small molecule models of the catalytic sites in non-heme carboxylate-bridged diiron enzymes. The phenyl rings of Ph4bdptz form a hydrophobic size-constrained pocket in which additional ligands can be accommodated, and they block the possible formation of tetranuclear species. As the steric bulk of the ancillary ligands is increased, the carboxylates shift from a syn, anti to a syn, syn coordination mode, and the Mossbauer spectra of the diiron(II) compounds clearly reflect the symmetry of the iron coordination environment. The oxidation chemistry of the diiron(II) compounds is presented.
Author:
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Category : Dissertation abstracts
Languages : en
Pages : 806
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Author: SeChin Chang
Publisher:
ISBN:
Category : Iron compounds
Languages : en
Pages : 408
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