A kinetico-mechanistic study on CuII deactivators employed in atom transfer radical polymerization

Zerk, Timothy J., Martinez, Manuel and Bernhardt, Paul V. (2016) A kinetico-mechanistic study on CuII deactivators employed in atom transfer radical polymerization. Inorganic Chemistry, 55 19: 9848-9857. doi:10.1021/acs.inorgchem.6b01700


Author Zerk, Timothy J.
Martinez, Manuel
Bernhardt, Paul V.
Title A kinetico-mechanistic study on CuII deactivators employed in atom transfer radical polymerization
Formatted title
A kinetico-mechanistic study on CuII deactivators employed in atom transfer radical polymerization
Journal name Inorganic Chemistry   Check publisher's open access policy
ISSN 1520-510X
0020-1669
Publication date 2016-10-03
Year available 2016
Sub-type Article (original research)
DOI 10.1021/acs.inorgchem.6b01700
Open Access Status Not yet assessed
Volume 55
Issue 19
Start page 9848
End page 9857
Total pages 10
Place of publication Washington, DC United States
Publisher American Chemical Society
Language eng
Abstract Copper complexes of tertiary amine ligands have emerged as the catalysts of choice in the extensively employed atom transfer radical polymerization (ATRP) protocol. The halide ligand substitution reactions of five-coordinate copper(II) complexes of tris[2-(dimethylamino)ethyl]amine (Me6tren), one of the most active ATRP catalysts, has been studied in a range of organic solvents using stopped-flow techniques. The kinetic and activation parameters indicate that substitution reactions on [CuII(Me6tren)X]+ (X- = Cl- and Br-) and [CuII(Me6tren)(Solv)]2+ (Solv = MeCN, DMF, DMSO, MeOH, EtOH) are dissociatively activated; this behavior is independent of the solvent used. Adjusting the effective concentration of the solvent by addition of an olefinic monomer to the solution does not affect the kinetics of the halide binding (kon) but can alter the outer-sphere association equilibrium constant (KOS) between reactants prior to the formal ligand substitution. Halide (X-/Y-) exchange reactions (X = Br and Y = Cl) involving the complex [Cu(Me6tren)X]+ and Y- reveal that the substitution is thermodynamically favored. The influence of solvent on the substitution reactions of [Cu(Me6tren)X]+ is complex; the more polar DMF confers a greater entropic driving force but larger enthalpic demands than MeCN. These substitution reactions are compared with those for copper(II) complexes bearing the tris[2-(diethylamino)ethyl]amine (Et6tren) and tris[2-(pyridyl)methyl]amine (tpa) ligands, which have also been used as catalysts for ATRP. Changing the ligand has a significant impact on the kinetics of X-/Y- exchange. These correlations are discussed in relation to the ability of five-coordinate [CuLX]+ complexes to deactivate radicals in ATRP.
Formatted abstract
The halide ligand substitution reactions of five-coordinate copper(II) complexes of tris[2-(dimethylamino)ethyl]amine (Me6tren), one of the most active atom transfer radical polymerization catalysts, have been studied in a range of organic solvents using stopped-flow techniques. The kinetic and activation parameters indicate that substitution reactions on [CuII(Me6tren)X]+ (X = Cl and Br) and [CuII(Me6tren)(Solv)]2+ (Solv = MeCN, DMF, DMSO, MeOH, EtOH) are dissociatively activated; this behavior is independent of the solvent used.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: HERDC Pre-Audit
School of Chemistry and Molecular Biosciences
 
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Created: Fri, 07 Oct 2016, 19:30:48 EST by Mrs Louise Nimwegen on behalf of School of Chemistry & Molecular Biosciences