MECHANISM OF OXIDATIVE ADDITION OF PALLADIUM(0) WITH AROMATIC IODIDES IN TOLUENE, MONITORED AT ULTRAMICROELECTRODES
MECHANISM OF OXIDATIVE ADDITION OF PALLADIUM(0) WITH AROMATIC IODIDES IN TOLUENE, MONITORED AT ULTRAMICROELECTRODES
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DOI：
10.1021/om00158a026
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发表时间：
1990-08-01
期刊：
影响因子：
2.8
通讯作者：
PFLUGER, F
中科院分区：
文献类型：
--
作者：
AMATORE, C;PFLUGER, F
用超微电极研究了甲苯中取代碘苯与四(三苯基膦)钯(O)的氧化加成反应机理和反应速率。其机理与以前在文献中报道的相同，并且与Hammett关联的斜率相似(在甲苯中为+2.3±0.2)。此外，极性的重要变化(a=7.58，在甲苯中为2.38)不影响活化热，并导致在两种溶剂中的活化熵相似。这表明，芳基卤化物与配位不饱和零价钯配合物Pd(PPh_3)_2加成的过渡态没有明显的离子性质。
The mechanism and rates of oxidative addition of substituted iodobenzenes to tetrakis (triphenyl-phosphine) palladium (O) is investigated in toluene by means of electrochemistry at ultramicroelectrodes. The mechanism is shown to be identical with that previously reported in THE and to correspond to a similar slope for Hammett’s correlation (p=+ 2 in THE vs+ 2.3±0.2 in toluene). Moreover, the important change in polarity (< a= 7.58 in THE and 2.38 in toluene) does notaffect the enthalpy of activation andleads to similar activation entropies in both solvents. This suggests that the transition state of addition of aryl halides to the coordinatively unsaturated zerovalent palladium complex Pd (PPh3) 2 has no significant ionic character.