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Synthesis, characterization, and reactivity studies of pyridine bis(anilide) iron complexes

Citation

Weintrob, Edward Charles (2012) Synthesis, characterization, and reactivity studies of pyridine bis(anilide) iron complexes. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechTHESIS:08112011-151147364

Abstract

The unifying concept within this thesis is the investigation of pyridine bis(anilide) (NNN) iron complexes. Within this topic, chapter 1 speaks to the motivation behind studying these complexes, and how they relate to problems within iron catalysis in general. Chapter 2 introduces the general ligand design and the features which are thought to give unique and desirable properties to the complexes derived from it. The mesityl susbstituted ligand [MesNNN]H2 and subsequently ferrous ([MesNNN]Fe(THF)) and ferric ([MesNNN]FeI and ([MesNNN]Fe)2O) complexes are synthesized. The properties of the complexes are investigated using a variety of characterization techniques. Such techniques include paramagnetic 1H NMR spectroscopy, X-ray crystallography, Evans method, cyclic voltammetry, DFT calculations, and UV-vis spectrscopy. A detailed explanation of the challenges and solutions involved in using paramagnetic NMR are discussed. Crystallographic data indicate that the ligand framework confers a quite unusual geometry about the iron center, especially for the ferrous derivative [MesNNN]Fe(THF). The factors involved in this geometry are discussed, and DFT calculations supplement this discussion. Chapter 3 focuses on the reactivity of the iron complexes. Various oxidants and reductants were employed which interconvert the iron derivatives in chapter 2. Organometallic derivatives [MesNNN]FeR (R = hydride, alkyl, aryl) were not accessible, likely due to homolytic processes. L ligand exchange for [MesNNN]Fe(THF) was investigated. Ethylene reversibly binds, while cyclohexene does not. Trimethylphosphonium methylidene displaces THF to generate [MesNNN]FeCH2PMe3. Although the I oxidation state was accessible for [MesNNN]Fe(THF) electrochemically, attempts to chemically produce Fe I complexes based on the NNN ligand led to multiple products. Chapter 4 focuses on the intramolecular C-H activation of [MesNNN]Fe(THF) with RN3 to afford [MesNNN-NHR]Fe (R = SiMe3, adamantyl). The kinetics of the reaction with Me3SiN3 was investigated in detail, and a mechanism was proposed. Iron complexes based on the pincer ligands [tBuNNN] and [ONO] were investigated.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Iron, pincer ligand, C-H activation, azide, anilide
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Bercaw, John E.
Thesis Committee:
  • Grubbs, Robert H. (chair)
  • Stoltz, Brian M.
  • Labinger, Jay A.
  • Peters, Jonas C.
  • Bercaw, John E.
Defense Date:28 July 2011
Author Email:edwardcharles.weintrob (AT) gmail.com
Funders:
Funding AgencyGrant Number
USDOE Office of Basic Energy SciencesDE-FG03-85ER13431
Moore FoundationUNSPECIFIED
Record Number:CaltechTHESIS:08112011-151147364
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:08112011-151147364
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/ic900083sDOIUNSPECIFIED
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:6579
Collection:CaltechTHESIS
Deposited By: Edward Weintrob
Deposited On:25 Aug 2011 18:42
Last Modified:26 Dec 2012 04:38

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