Auxiliary proton-influenced metal-mediated reactions: dioxygen activation, anion coordination, and catalysis
type: CreativeWork
description: Studies on the incorporation of hydrogen-bonding groups into the second coordination sphere of Cu complexes have revealed that O2 reactivity is enhanced in the presence of these functional groups. The effects of intramolecular hydrogen-bonding on the oxygen affinity of CuN3+ derivatives, where N3 = tris(2-picolin-6-yl)methane (tripic) and analogues are presented in Chapter 2. The key synthetic methodology relies on Pd-catalyzed coupling reactions of lithiated 6-methyl-2-pyridone with bromopyridyl derivatives. These building blocks allow the preparation of tridentate N3 ligands decorated with OH and OMe substituents flanking the fourth coordination site of a tetrahedral complex. Crystallographic characterization of the ligand complemented with two methyl and one OH group revealed that it exists as the pyridone tautomer with a bifurcated hydrogen-bond. Coupling of these tridendate ligands gives the corresponding hydroxy- and methoxy-functionalized bis(tripodal) ligands. Cu[bis(2-methylpyrid-6-yl)(2-hydroxypyrid-6-yl)methane](NCMe)+ oxidizes readily in air to afford a mixed valence type III Cu1.5 dimer, and can be reversed through the addition of decamethylferrocene and acid. The reactivity with dioxygen requires the hydroxyl substituent: neither [Cu(tripic)(NCMe)]+ nor the methoxy complexes display O2 reactivity. A similar mixed valence dimer was found to form upon exposing the dicopper(I) complex of a tetrahydroxy bis(tridentate) ligand to air. The dicopper(I) complex of the analogous tetramethoxy N6-ligand instead reversibly binds O2. Deprotonation of Cu[bis(2-methylpyrid-6-yl)(2-hydroxypyrid-6-yl)methane](CO)+ afforded the neutral Cu(I) carbonyl complex. Deprotonation of Cu[bis(2-methylpyrid-6-yl)(2-hydroxypyrid-6-yl)methane](NCMe)+ gave a Cu(I) dimer that does not contain MeCN, which can be reoxidized, reprotonated, and carbonylated. The structures of bis(2-methylpyrid-6-yl)(2-pyridon-6-yl)methane, a bimetallic Cu(I)(NCMe) complex of the N6-tetramethoxylated ligan…
abstract: Studies on the incorporation of hydrogen-bonding groups into the second coordination sphere of Cu complexes have revealed that O2 reactivity is enhanced in the presence of these functional groups. The effects of intramolecular hydrogen-bonding on the oxygen affinity of CuN3+ derivatives, where N3 = tris(2-picolin-6-yl)methane (tripic) and analogues are presented in Chapter 2. The key synthetic methodology relies on Pd-catalyzed coupling reactions of lithiated 6-methyl-2-pyridone with bromopyridyl derivatives. These building blocks allow the preparation of tridentate N3 ligands decorated with OH and OMe substituents flanking the fourth coordination site of a tetrahedral complex. Crystallographic characterization of the ligand complemented with two methyl and one OH group revealed that it exists as the pyridone tautomer with a bifurcated hydrogen-bond. Coupling of these tridendate ligands gives the corresponding hydroxy- and methoxy-functionalized bis(tripodal) ligands. Cu[bis(2-methylpyrid-6-yl)(2-hydroxypyrid-6-yl)methane](NCMe)+ oxidizes readily in air to afford a mixed valence type III Cu1.5 dimer, and can be reversed through the addition of decamethylferrocene and acid. The reactivity with dioxygen requires the hydroxyl substituent: neither [Cu(tripic)(NCMe)]+ nor the methoxy complexes display O2 reactivity. A similar mixed valence dimer was found to form upon exposing the dicopper(I) complex of a tetrahydroxy bis(tridentate) ligand to air. The dicopper(I) complex of the analogous tetramethoxy N6-ligand instead reversibly binds O2. Deprotonation of Cu[bis(2-methylpyrid-6-yl)(2-hydroxypyrid-6-yl)methane](CO)+ afforded the neutral Cu(I) carbonyl complex. Deprotonation of Cu[bis(2-methylpyrid-6-yl)(2-hydroxypyrid-6-yl)methane](NCMe)+ gave a Cu(I) dimer that does not contain MeCN, which can be reoxidized, reprotonated, and carbonylated. The structures of bis(2-methylpyrid-6-yl)(2-pyridon-6-yl)methane, a bimetallic Cu(I)(NCMe) complex of the N6-tetramethoxylated ligan…
author: Letko, Christopher
language: en
keywords: Dioxygen Reduction, Second Coordination Sphere, Hydrogen Bonding, Transfer Hydrogenation
date published: 2012-02-01T00:53:18Z
date modified: 2026-07-22T22:25:27Z
provider: University of Illinois - Urbana-Champaign
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Illinois at Urbana-Champaign

PropertyValue
property ID: Handle
value: http://hdl.handle.net/2142/29511