with five haloarenes. Reductive elimination of aryl chloride was most favored thermodynamically, and elimination of aryl iodide was the least favored. However, reductive elimination from the aryl chloride complex was the slowest, and reductive elimination from the aryl bromide complex was the fastest. These data show that the electronic properties of the halide, not the thermodynamic driving force for
单体的三配位芳基
钯 (II) 卤化物络合物经过芳基卤化物的还原消除,形成游离的卤代
芳烃和 Pd(0)。将 P(t-Bu)3 添加到 Pd[P(t-Bu)3](Ar)(X) (X = Cl, Br, I) 后,观察到芳基
氯化物、
溴化物和
碘化物的还原消除。用五种卤代
芳烃建立了观察还原消除和氧化加成之间平衡的条件。在热力学上最有利于芳基
氯的还原消除,而最不利于芳基
碘的消除。然而,芳基
氯络合物的还原消除最慢,芳基
溴络合物的还原消除最快。这些数据表明卤化物的电子特性,而不是消除反应加成的热力学驱动力,控制卤代
芳烃的添加和消除速率。机理数据表明,芳基
溴化物可逆还原消除形成 Pd[P(t-Bu)3] 和游离芳基
溴化物,随后 P(t-Bu)3 限速配位形成 Pd[P(t-Bu) )3]2。