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Electronic Structure and Reactivity of Metal Complexes


Barth, Alexandra Teresa (2023) Electronic Structure and Reactivity of Metal Complexes. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/k66v-1c93.


Transition metals are at the core of addressing global energy needs. Functioning as catalysts, these systems have long demonstrated competency to promote thermodynamically challenging reactions, lowering energetic barriers and facilitating desired transformations with applied light or potential. Employing infrared, visible, ultraviolet, and x-ray spectroscopy, chemists are afforded insight into the electronic structures of transition metal complexes, investigating ligand field strengths and metal-ligand interactions. Addition of time-resolved techniques affords resolution of dynamic processes in molecular species, such as electron transfer pathways.

Chapter 1 reviews the electronic structure and reactivity of homoleptic tungsten(0) arylisocyanides W(CNAr)₆ to provide the foundation for much of this work.

In Chapter 2, application of W(CNAr)₆ species for one- and two-photon photoredox catalysis are explored. The two-photon absorption cross-sections of W(CNAr)₆ are remarkably large (δ₈₁₀ = 180–1900 GM) and enable these photocatalysts to operate under excitation from visible or near infrared light. Photoredox activity is evaluated via base-promoted homolytic aromatic substitution (BHAS) reaction of thermodynamically challenging substrates. In Chapter 3, solvent perturbations enhance visible light-activated BHAS catalysis from W(CNAr)₆. Increased solvent dielectric (benzene to 1,2-difluorobenzene) and solvated electrolyte combine to increase *W(CNAr)₆ quenching rates up to one order of magnitude with greater cage-escape yields.

In Chapter 4, the electronic structure of linear gold(I) arylisocyanide complexes ([Au(CNDipp-R)₂]⁺; CNDipp = 2,6-diisopropylphenylisocyanide) are assigned using insights from UV-visible spectroscopy and time-dependent density functional theory (TD-DFT) calculations. In Chapter 5, the electronic structure of Fe(II) and Co(II) quaterpyridine photo-/electro-catalysts for CO₂ reduction are evaluated using UV-visible-NIR, ¹H NMR, Mössbauer, and infrared spectra. Assignment of the absorption transitions are supported by TD-DFT calculations.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:electronic structure; spectroscopy; photochemistry; photoredox catalysis
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Awards:The Candace Rypisi Outstanding Mentor Award, 2020.
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Gray, Harry B.
Thesis Committee:
  • See, Kimberly (chair)
  • Gray, Harry B.
  • Okumura, Mitchio
  • Cushing, Scott K.
Defense Date:5 December 2022
Funding AgencyGrant Number
National Science Foundation1763429
National Science Foundation Graduate Research Fellowship1745301
Record Number:CaltechTHESIS:12282022-061839565
Persistent URL:
Related URLs:
URLURL TypeDescription adapted for Chapter 2. adapted for Chapter 3.
Barth, Alexandra Teresa0000-0002-1813-4029
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:15080
Deposited By: Alexandra Barth
Deposited On:17 Jan 2023 17:35
Last Modified:21 Jul 2023 20:19

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