Mechanistic Insight into the Protonolysis of the Pt−C Bond as a Model for C−H Bond Activation by Platinum(II) Complexes
作者:Raffaello Romeo、Giuseppina D'Amico
DOI:10.1021/om060217n
日期:2006.7.1
The kinetic and NMR features of the protonolysis reactions on platinum(II) alkyl complexes of the types cis-[PtMe2L2], [PtMe2(L-L)], cis-[PtMeClL2], and [PtMeCl(L-L)] (L = PEt3, P(Pri)3, PCy3, P(4-MePh)3, L-L = dppm, dppe, dppp, dppb) in methanol suggest a rate-determining proton attack at the Pt−C bond. In contrast, a multistep oxidative-addition−reductive-elimination mechanism characterizes the methane
顺式-[PtMe 2 L 2 ],[PtMe 2(LL)],顺式-[PtMeClL 2 ]和[PtMeCl(LL)]的铂(II)烷基络合物的质子分解反应的动力学和NMR特征。(L = PEt 3,P(Pr i)3,PCy 3,P(4-MePh)3,LL = dppm,dppe,dppp,dppb)在甲醇中显示出决定Pt-C键质子进攻的速率。相比之下,多步氧化加减还原机理表征了相应反式-[PtMeClL 2的质子化过程中的甲烷损失] 物种。在暗示这两个系统的不同反应途径方面具有特殊诊断性的工具是(i)动力学氘同位素实验的结果不同(ii)低温1 H NMR检测或不检测Pt(IV)氢化烷基中间产物实验,以及(iii)检测或不存在同位素加扰以及将氘掺入Pt-CH 3中,并损失一定范围的CH n D n - 4异构体。对于所有系统,质子分解的速度受配体空间拥塞的阻碍,受配体电子的贡献而加速,并且几乎