title: Unusually stable palladium(IV) complexes: detailed mechanistic investigation of C-O bond-forming reductive elimination.
abstract: 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 DeltaS of -1.4 +/- 1.9 and 4.2 +/- 1.4 in CDCl3 and DMSO, respectively), and Hammett analysis (which shows rho = -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.
authors.affiliation: Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, USA.
authors.forename: Allison R
authors.initials: AR
authors.lastname: Dick
authors.forename: Jeff W
authors.initials: JW
authors.lastname: Kampf
authors.forename: Melanie S
authors.initials: MS
authors.lastname: Sanford
mesh_terms: D018360:Crystallography, X-Ray; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010084:Oxidation-Reduction; D010165:Palladium / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; D010165:Palladium