Development of systems for isolation of high-valent nickel complexes and their reactivity

Heberer, Neil Thomas

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https://hdl.handle.net/2142/113158 Copy

Description

Title

Development of systems for isolation of high-valent nickel complexes and their reactivity

Author(s)

Heberer, Neil Thomas

Issue Date

2021-07-16

Director of Research (if dissertation) or Advisor (if thesis)

Mirica, Liviu M

Department of Study

Chemistry

Discipline

Chemistry

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• nickel
• high-valent, triazacyclononane
• pyridinophane
• organometallics
• catalysis
• cross-coupling

Abstract

Inspired by work published in our group utilizing macrocyclic nitrogen based pyridinophane (N4) and triazacyclononane (tacn) ligands for the isolation and study of high-valent nickel and palladium compounds, chiral variants of these ligands were synthesized in attempts to isolate high-valent organometallic nickel complexes that could play a role in enantioselective crosscoupling reactions. Utilizing readily available chiral pool primary amines, the synthesis of N4 type ligands can be amended to install chirality on the tertiary amines of the ligand, which commonly bind through dative interactions with the metal center in high-valent oxidation states. Furthermore, the synthesis can be expanded to N3 type pyridinophane compounds like N3CBr type ligands, allowing for on-ligand reactivity studies to be conducted. With these ligands in hand, a secondary organometallic nucleophile was synthesized which could allow for the synthesis of organometallic nickel complexes. The reactivity of these complexes was then examined, with hopes that insight into the role of high-valent complexes and the method for stereoinduction in enantioselective cross-coupling reactions could then be better understood. Furthermore, a synthetic route to novel chiral variants of triazacyclononane ligands was developed based on a ‘crab-like’ synthesis published by the Scarborough group in 2018. This synthesis relies on commercially available alpha-hydroxy acids, and the substituents on the ligand can be varied in a multitude of locations. This ligand synthesis allows for installation of chirality on the methylene backbone of the ligand, which will hopefully result in good chiral projection into the open binding sites of the metal complex. Further efforts to develop reactivity with this system are currently underway.

Graduation Semester

2021-08

Type of Resource

Thesis

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http://hdl.handle.net/2142/113158

Copyright and License Information

Copyright 2021 Neil Heberer

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