Unusually Stable Palladium(IV) Complexes:  Detailed Mechanistic Investigation of C−O Bond-Forming Reductive Elimination

This communication describes the synthesis of a family of unusually stable palladium(IV) complexes containing two chelating 2-phenylpyridine ligands and two benzoates. These complexes undergo clean C−O bond-forming reductive elimination upon heating, and the mechanism of this catalytically relevant...

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Bibliographic Details
Published in:Journal of the American Chemical Society 2005-09, Vol.127 (37), p.12790-12791
Main Authors: Dick, Allison R, Kampf, Jeff W, Sanford, Melanie S
Format: Article
Language:English
Subjects:
Chemistry
Crystallography, X-Ray
Exact sciences and technology
Inorganic chemistry and origins of life
Kinetics and mechanism of reactions
Models, Molecular
Molecular Structure
Organometallic Compounds - chemical synthesis
Organometallic Compounds - chemistry
Oxidation-Reduction
Palladium - chemistry
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Summary:This communication describes the synthesis of a family of unusually stable palladium(IV) complexes containing two chelating 2-phenylpyridine ligands and two benzoates. These complexes undergo clean C−O bond-forming reductive elimination upon heating, and the mechanism of this catalytically relevant process has been studied in detail. Solvent effects, crossover experiments, Eyring plots (which show ΔS ⧧ of −1.4 ± 1.9 and 4.2 ± 1.4 in CDCl3 and DMSO, respectively), and Hammett analysis (which shows ρ = −1.36 ± 0.04 upon substitution of the para-benzoate substituent) all suggest that reductive elimination does not proceed via initial dissociation of a benzoate ligand. Instead, an unusual mechanism involving pre-equilibrium dissociation of the N-arm of the phenylpyridine ligand is proposed.
ISSN:0002-7863
1520-5126
DOI:10.1021/ja0541940