Synthesis of Early Transition Metal Complexes Supported by Pyrrolyl and Indolyl Based Ligands

High oxidation state early transition metal complexes are Lewis acidic and electrophilic. The electrophilic center promotes the coordination and insertion of electron-rich substrates; such as alkenes, alkynes, and epoxides. Anionic ligands enable the metal center to retain Lewis acidity for catalytic applications and chelating ligands increase stability due to the chelate effect. Frequently, Constrained Geometry Catalysts (CGC) are comprised of early transition metals supported by chelating ligands. The chelating CGC ligands usually contain an η5-dienyl moiety tethered to anionic donor. The pendent donor conventionally is an amide or alkoxide derivative which in turn quenches some of the Lewis acidity of the transition metal through E-M π-donation (E = O, N) of lone pair electrons. Substituting heterocyclic nitrogen moiety (pyrrole or indole) for the pendent donor will reduce the N-M π-donation due to lone pair delocalization within the aromatic ring. This thesis reports further developments of the cyclopentadienyl derivative of constrained geometry ligands featuring indolyl- and pyrrolyl- donor moieties and indolyl- and pyrrolyl- supported group 5 imido complexes.In chapter 2, the synthesis and characterization of a series of dipyrrolyl- and diindolylmethane precursors envisioned to produce the Cp-based trianionic ligand are reported. Three new methanes are described, 5-(chloromethyl)dipyrrolylmethane, 2,2’-di(5-mesityl-1H-pyrrol-2-yl) ethyl chloride, and ethyl 2-(2,2’-di-3-methylindolyl)propionate, along with attempts to react with sodium cyclopentadienyl. In additional, tetramethylcyclopentadienyl acetaldehyde diethyl acetyl was synthesized and reactivity with pyrrole and 3-methylindole is discussed. Chapter 3 reports synthesis and characterization of a series of elementary Group 5 imido complexes supported by pyrrolyl- and indolyl- ligands. A total of six compounds were synthesized by amine elimination and characterization included 1H and 13C NMR spectroscopy. The structure of (tBuN)Nb{di(3-methylindolyl)phenylmethane}(NEt2)(NHEt2) was further characterized by X-ray crystallography to confirm connectivity. These complexes are envisioned to have broad application to catalytic processes.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Chemistry

Grantor dc:publisher

University of Toledo

Year dc:date

2013

Author dc:creator

• Yeisley, Christopher R.

Contributors dc:contributor

• Mason, Mark

• Chemistry
• CGCs
• Group 5 imido
• trianionic
• indole
• pyrrole

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: some rights reserved. It is licensed for use under a Creative Commons license. Specific terms and permissions are available from this document's record in the OhioLINK ETD Center.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=toledo1363282845

OAI identifier oai:identifier

oai:etd.ohiolink.edu:toledo1363282845