ja5b04613_si_003.cif (513.42 kB)
Halide-Dependent Mechanisms of Reductive Elimination from Gold(III)
dataset
posted on 2015-06-24, 00:00 authored by Matthew
S. Winston, William J. Wolf, F. Dean TosteTwo
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 Caryl–X and Caryl–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 Caryl–CF3 bond formation increases in the order X = I < Br < Cl <
F, with exclusively Caryl–I bond formation when
X = I, and exclusively Caryl–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 Caryl–X and Caryl–CF3 reductive elimination.