Synthesis of Chromium, Iron, and Nickel Complexes Using Aryl-based Chelates as Ancillary Ligands and a Series of Bis([alpha]-iminopyridyl) Iron Compounds with Varying Donor Ligands

Synthesis of Chromium, Iron, and Nickel Complexes Using Aryl-based Chelates as Ancillary Ligands and a Series of Bis([alpha]-iminopyridyl) Iron Compounds with Varying Donor Ligands
Author: Emily C. Volpe
Publisher:
Total Pages: 0
Release: 2010
Genre:
ISBN:

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Several classes of aryl-based chelates containing pyridine, oxazoline, or imine donors and their reactivity with 1st-row transition metals were investigated in light of the potential of carbon-based ligands to impart strong ligand fields. Heterolytic C-H bond activation of 2-phenylpyridine was achieved with Ni(OTf)2. The cyclometalated product and its derivatives undergo substitution, insertion, and additional cyclometalation reactions. Aryl-oxazolines display a range of reactivity patterns which are dependent on the reaction conditions, the metal, and the particular ligand employed. Aryl-aryl coupling, oxazoline ring-opening, and methylene deprotonation were examined, but were tangential to the goal of making metal-aryl bonds. Successful arylation of nickel, iron and chromium was accomplished using a methylated benzyl-oxazoline aryl anion, and the spectroscopic, structural, and magnetic properties of these complexes are described. Tridentate arylpyridylimines or diarylimines undergo facile arylation with cis-(Me3P)4Fe(Me)2 to give low-spin, sixcoordinate iron compounds. Their thermal and oxidation behavior are studied, and the spectroscopic properties of their azaallyl derivatives are compared to previouslyreported, related species. A highly-fluorinated congener of the diarylimine iron complexes was sought, and preliminary evidence of its divergent reactivity is noted. Finally, a series of iminopyridine complexes of the formula (N,N'-[alpha]- iminopyridyl)2Fe(L/X)n have been examined by X-ray and Mossbauer spectroscopy. The redox-active nature of the iminopyridine ligands and the donating ability of the additional L/X ligands have been assessed.

Synthesis of New Iron and Nickel Complexes

Synthesis of New Iron and Nickel Complexes
Author: Anthony Kermagoret
Publisher:
Total Pages:
Release: 2007
Genre:
ISBN:

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My Ph-D thesis concerns the study of the catalytic oligomerization reaction with nickel, iron and cobalt complexes coordinated by N-O, P-N, N-P-N, P-O and P-N-P type ligands with a N donor atom represented by an oxazoline or a pyridine heterocycle. These complexes activated by a cocatalyst such as MAO or AlEtCl2 showed high activities and a high selectivity of C4 olefins in ethylene oligomerization. The nickel complexes with P-N chelates showed a high impact of the P substituents on the oligomerization selectivities. Moreover, the crystallographic studies on nickel complexes coordinated by N-O and P-N type ligands showed the formation of mono-, di- and tetranuclear complexes. The cobalt, iron and palladium complexes with N-P-N ligands highlighted original N-N, P-N or N-P-N coordination modes of the ligands influenced by the ligand substituents and the metal center.

Organochromium Chemistry with Formally Neutral, Chelating Ancillary Ligands

Organochromium Chemistry with Formally Neutral, Chelating Ancillary Ligands
Author: Kevin Allen Kreisel
Publisher: ProQuest
Total Pages:
Release: 2008
Genre: Chelates
ISBN: 9780549388425

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This dissertation describes research on chromium complexes with formally neutral, chelating ligands. The goal of this research is the fundamental study of organochromium chemistry with the hope of preparing Cr(II) complexes that are active for the polymerization or oligomerization of ethylene. This would provide evidence for Cr(II) to be active for these processes. Chapter 1 of this dissertation describes the synthesis and characterization of a series of chromium complexes supported by a chelating N-heterocyclic carbene ligand. The second chapter details the preparation and structural characterization of several complexes of chromium supported by several diimine ligands. The third chapter examines the organochromium chemistry derived from the complexes described in chapter 2. The final chapter entails the synthesis of the shortest metal-metal distance ever reported.