title: Halide-Dependent Mechanisms of Reductive Elimination from Gold(III).
abstract: Two unique organometallic halide series (Ph3P)Au(4-Me-C6H4)(CF3)(X) and (Cy3P)Au(4-F-C6H4)(CF3)(X) (X = I, Br, Cl, F) have been synthesized. The PPh3-supported complexes can undergo both C(aryl)-X and C(aryl)-CF3 reductive elimination. Mechanistic studies of thermolysis at 122 °C reveal a dramatic reactivity and kinetic selectivity dependence on halide ligand. For X = I or F, zero-order kinetic behavior is observed, while for X = Cl or Br, kinetic studies implicate product catalysis. The selectivity for C(aryl)-CF3 bond formation increases in the order X = I < Br < Cl < F, with exclusively C(aryl)-I bond formation when X = I, and exclusively C(aryl)-CF3 bond formation when X = F. Thermodynamic measurements show that Au(III)-X bond dissociation energies increase in the order X = I < Br < Cl, and that ground state Au(III)-X bond strength ultimately dictates selectivities for C(aryl)-X and C(aryl)-CF3 reductive elimination.
authors.affiliation: Department of Chemistry, University of California, Berkeley, California 94720, United States.
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Winston
authors.affiliation: Department of Chemistry, University of California, Berkeley, California 94720, United States.
authors.forename: William J
authors.initials: WJ
authors.lastname: Wolf
authors.affiliation: Department of Chemistry, University of California, Berkeley, California 94720, United States.
authors.forename: F Dean
authors.initials: FD
authors.lastname: Toste
mesh_terms: D001965:Bromides / Q000737:chemistry; D002712:Chlorides / Q000737:chemistry; D005459:Fluorides / Q000737:chemistry; D006219:Halogens / Q000737:chemistry*; D006358:Hot Temperature; D007454:Iodides / Q000737:chemistry; D008024:Ligands; D008958:Models, Molecular; D050607:Organogold Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D013816:Thermodynamics
chemical_list: D001965:Bromides; D002712:Chlorides; D006219:Halogens; D007454:Iodides; D008024:Ligands; D050607:Organogold Compounds; D005459:Fluorides