ISOTOPE EFFECTS IN ARENE C-H BOND ACTIVATION BY [(C5ME5)RH(PME3)]
ISOTOPE EFFECTS IN ARENE C-H BOND ACTIVATION BY [(C5ME5)RH(PME3)]
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DOI：
10.1021/ja00276a019
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发表时间：
1986-08-06
影响因子：
15
通讯作者：
FEHER, FJ
中科院分区：
文献类型：
--
作者：
JONES, WD;FEHER, FJ
本文研究了中间体[（C_5Me_5）Rh（PMe_3）]活化芳烃CH键的同位素效应。芳烃活化反应的速率控制步骤是与苯中的双键配位，其kH/kD比值为1.05（6），而第二步是与配位芳烃的CH键进行氧化加成反应，kH/kD比值为1.4。对于更稳定的苯基氢化物络合物（C5 Me 5）-Rh（PMe 3）（C6 D5）H和在苯环邻位含有氢的络合物（C5 Me 5）Rh（PMe 3）（o-C6 D4 H）D之间的平衡，同位素效应KH/D显示出对氢（相对于氘）的2.7的金属的偏好。研究了（C_5Me_5）Rh（PMe_3）（3，5-C_6H_3Me_2）H与（C_5Me_5）Rh（PMe_3）（3，5-C_6H_3Me_2）H还原消除间二甲苯的动力学同位素效应。（C_5Me_5）Rh（PMe_3）（3，5-C_6H_3Me_2）D是反相的，其Δ hAd= 0.51.氘代苯衍生物的数据分析证实，还原消除步骤的动力学同位素是相反的。用[DBEt 3]还原[（C5 Me 5）Rh-（PMe 3）（CH 3）（THF）]+制备配合物（C5 Me 5）Rh（PMe 3）（CH 3）D，得到了（C5 Me 5）Rh（PMe 3）（CH 3）D和（C5 Me 5）Rh-（PMe 3）（CH 2D）H。
Theisotope effects involved in the activation of arene CH bonds by the intermediate [(C5Me5) Rh (PMe3)] have been investigated. The ratio k^/k^ for coordinationto a double bond in benzene (the rate-determining step of arene activation) is found to be 1.05 (6), whereas kH/kD= 1.4 for the second step in which the CH bond of the coordinated arene undergoes oxidative addition. The isotope effect KH/D for the equilibrium between the more stable phenyl hydride complex (C5Me5)-Rh (PMe3)(C6D5) H and the complex containing hydrogen in the ortho position of the phenyl ring (C5Me5) Rh (PMe3)(o-C6D4H) D shows a preference for hydrogen (vs. deuterium) on the metal of 2.7. The kinetic isotope effect for reductive elimination and dissociation of m-xylene from (C5Me5) Rh (PMe3)(3, 5-C6H3Me2) H vs.(C5Me5) Rh (PMe3)(3, 5-C6H3Me2) D is found to be inverse, with &hAd= 0.51. Analysis of the data for the deuterated benzene derivativesconfirms that the kinetic isotope for the reductive elimination step is inverse. Attempts to prepare the complex (C5Me5) Rh (PMe3)(CH3) D by reductionof [(C5Me5) Rh-(PMe3)(CH3)(THF)]+ with [DBEt3]'resulted in the formationof both (C5Me5) Rh (PMe3)(CH3) D and (C5Me5) Rh-(PMe3)(CH2D) H.