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Exploring the Photophysics and React...
Cagan, David Abraham,

 

  • Exploring the Photophysics and Reactivity of Nickel-Bipyridine Cross-Coupling Catalysts /
  • 紀錄類型: 書目-語言資料,印刷品 : Monograph/item
    正題名/作者: Exploring the Photophysics and Reactivity of Nickel-Bipyridine Cross-Coupling Catalysts // David Abraham Cagan.
    作者: Cagan, David Abraham,
    面頁冊數: 1 electronic resource (303 pages)
    附註: Source: Dissertations Abstracts International, Volume: 86-04, Section: B.
    提要註: Ni(II)-bipyridine (bpy) aryl halide complexes have been prized for nearly a decade for their catalytic potency to facilitate cross-coupling reactions. To achieve these transformations, the energy from light is leveraged to drive the key catalytic processes. Thus, Ni-mediated photoredox catalysis provides an attractive and sustainable means to replace precious metal catalysts. However, precise mechanistic information regarding how these transformations occur is limited. This thesis thus focuses on a dual experimental and computational analysis of Ni(II)-bpy aryl halide complexes and their photoproducts to provide insight into the specific photophysical and chemical pathways that these catalysts undertake for cross-coupling reactions. The first chapter is a review of the proposed mechanisms presented for Ni-mediated photoredox catalysis. Therein, certain portions of this work are also summarized. The second chapter provides a computational description of the Ni(II) excited states. The third chapter expands on this analysis with experiment, elucidating the photophysical pathway that grants entry into dark Ni(I)/Ni(III) catalytic cycles. Together, chapters two and three show that Ni(II)-bpy aryl halide complexes form low-valent Ni(I)-bpy halide species by an aryl-to-Ni ligand-to-metal charge transfer. Chapter four outlines a method to generate and study these reactive Ni(I)-bpy halide intermediates, identifying their mechanism of C(sp 2)-Cl bond activation as nucleophilic aromatic substitution, tunable via the energies of the 3 d-orbitals and the effective nuclear charge of Ni. The final chapter finds that these low-valent Ni species are competitive light-absorbers, and it presents a study into their ultrafast photophysics, marking the first of its kind on any Ni(I) complex. The excited-state relaxation dynamics of Ni(I)-bpy halide complexes are well described by vibronic Marcus theory, spanning the normal and inverted regions as a result of simple changes to the bpy substituents. Altogether, these studies have provided a framework to gain electronic structural control over Ni-meditated photoredox catalysis and, thus, guides the use of photonic energy as a sustainable alternative to precious metal catalysis.
    Contained By: Dissertations Abstracts International86-04B.
    標題: Medical imaging. -
    電子資源: http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=31524045
    ISBN: 9798342110051
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