New redox-active ligands on iron and cobalt for C-C bond forming reactions

Bayless, Michael Bruce

Title:

New redox-active ligands on iron and cobalt for C-C bond forming reactions

dc.contributor.advisor	Soper, Jake D.
dc.contributor.author	Bayless, Michael Bruce
dc.contributor.committeeMember	Barefield, Edward Kent
dc.contributor.committeeMember	Wilkinson, Angus P.
dc.contributor.committeeMember	Zhang, W. John
dc.contributor.committeeMember	Jones, Christopher W.
dc.contributor.department	Chemistry and Biochemistry
dc.date.accessioned	2014-08-27T13:38:58Z
dc.date.available	2014-08-27T13:38:58Z
dc.date.created	2014-08
dc.date.issued	2014-06-25
dc.date.submitted	August 2014
dc.date.updated	2014-08-27T13:38:58Z
dc.description.abstract	Redox-active ligands deliver redox equivalents to impart multi-electron functionality at 3d metals that typically undergo to one electron redox events. It was proposed that 3d metals with redox-active ligands could form unusually well-defined catalysts for C-C bond forming reactions to mimic palladium-type reactivity. Therefore, several new complexes containing an iron or cobalt with redox-active ligands were synthesized and tested for their ability to form new C-C bonds. A bis(iminosemiquinone) iron (III) complex was able to homocouple aryl Grignards using dioxygen as the terminal oxidant. However, ligand redistribution prevented detailed mechanistic study of the C-C bond forming reaction and led to catalyst degradation. To address the challenges seen in the iron catalyst a new cobalt electron transfer (ET) series containing a pincer-type bis(phenolate) N-heterocyclic carbene ligand (CoNHC) was synthesized. Studies indicate the CoNHC ET series spans multiple-electrons by corporative metal and ligand redox. These complexes were evaluated for cross-coupling of alkyl halides and aryl Grignards. Mechanistic studies imply that the low cross-coupling yields were due to ligand degradation. However, CoNHC catalytically activate cross-couples ether nitriles and aryl Grignards via a novel C-O bond activation leading to a new C-C bond. Findings concerning redox-active ligands on iron and cobalt for C-C bond forming reactions and implications for future research are discussed.
dc.description.degree	Ph.D.
dc.format.mimetype	application/pdf
dc.identifier.uri	http://hdl.handle.net/1853/52286
dc.language.iso	en_US
dc.publisher	Georgia Institute of Technology
dc.subject	Redox-active ligand
dc.subject	3d metal catalysis
dc.subject	Cross-coupling
dc.subject	Homocoupling
dc.subject	C-O activition
dc.title	New redox-active ligands on iron and cobalt for C-C bond forming reactions
dc.type	Text
dc.type.genre	Dissertation
dspace.entity.type	Publication
local.contributor.advisor	Soper, Jake D.
local.contributor.corporatename	School of Chemistry and Biochemistry
local.contributor.corporatename	College of Sciences
relation.isAdvisorOfPublication	328dce39-b277-4839-b03f-60f002a8a195
relation.isOrgUnitOfPublication	f1725b93-3ab8-4c47-a4c3-3596c03d6f1e
relation.isOrgUnitOfPublication	85042be6-2d68-4e07-b384-e1f908fae48a
thesis.degree.level	Doctoral