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Transition Metals as Catalysts for Cross-Coupling and Dinitrogen Fixation

Citation

Buscagan, Trixia Marie (2018) Transition Metals as Catalysts for Cross-Coupling and Dinitrogen Fixation. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z98P5XPM. https://resolver.caltech.edu/CaltechTHESIS:09202017-130540216

Abstract

Transition metals are used as catalysts in the laboratory and by nature to facilitate difficult chemical transformations. Herein, three different metal containing catalysts are discussed: Pd and Ni catalysts towards the formation of carbon-carbon (C-C) bonds and Fe catalysts towards the reduction of N2 to NH3.

In Chapter 2, mechanistic studies of Pd- and Ni-catalyzed cross-coupling reactions are discussed. The mechanism of transmetalation of a Pd-catalyzed Suzuki cross-coupling reaction is studied using a stereochemical probe, revealing that transmetalation occurs with retention of configuration, consistent with transmetalation occurring through a frontside-attack mechanism. Next, to explore the viability of a transmetalation first pathway in an asymmetric Negishi cross-coupling reaction, S = 1/2 NiIBr and NiI–alkyl complexes were synthesized, crystallographically characterized, and their reactivities explored. Based on these reactivity studies, evidence against a transmetalation first pathway is provided using a variety of spectroscopic methods.

In Chapter 3, new Fe(N2)(H)x complexes are synthesized. These complexes catalyze the reduction of N2 to NH3 and the yields for NH3 are improved if the reactions are performed in the presence of Hg lamp photolysis. Preliminary mechanistic studies exploring the role of light are discussed. In the final chapter, new ligand scaffolds are developed that can bind a Lewis acidic and Lewis basic metal center. These ligand frameworks support one- and two-atom bridges between the two metal sites. Finally, we discovered that some of the new complexes are catalysts for N2 to NH3 reduction and olefin hydrogenation.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:transition metal, catalysis, dinitrogen reduction, cross coupling, iron catalyst, nickel catalyst
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Peters, Jonas C.
Thesis Committee:
  • Reisman, Sarah E. (chair)
  • Fu, Gregory C.
  • Agapie, Theodor
  • Rees, Douglas C.
  • Peters, Jonas C.
Defense Date:28 August 2017
Record Number:CaltechTHESIS:09202017-130540216
Persistent URL:https://resolver.caltech.edu/CaltechTHESIS:09202017-130540216
DOI:10.7907/Z98P5XPM
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1002/anie.201703244DOIArticle adapted for Chapter 3.
ORCID:
AuthorORCID
Buscagan, Trixia Marie0000-0001-8242-9203
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10443
Collection:CaltechTHESIS
Deposited By: Trixia Buscagan
Deposited On:25 Sep 2017 22:47
Last Modified:04 Oct 2019 00:17

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