The platinum(0) complex [Pt(tcep)3], tcep = P(CH2CH2CN)3, catalyses the formation of tcep from PH3 and CH2CHCN. The complexes [M(tcep)3] (M = Pt, Pd or Ni) and [MCl(tcep)3] (M = Rh or Ir) are compared for their catalysis of the reaction of PH(CH2CH2CN)2 with CH2CHCN to give tcep and it is shown that the platinum(0) complex is the most efficient. The platinum(0) catalysis has been studied in detail, monitoring the kinetics by 31P-1H} NMR spectroscopy. It is revealed that the kinetics are a complex function of the concentration of product tcep. Qualitatively, the rates also depend on [CH2CHCN] and [catalyst]. Both 31P-1H} and 195Pt-1H} NMR spectroscopy suggests that addition of CH2CHCN to [Pt(tcep)3] gives the complex [Pt(tcep)2(η2-CH2CHCN)] which undergoes phosphine exchange on the NMR time-scale. The binuclear complex [Pt2H2(tcep)2µ-P(CH2CH2CN)2}2], formed upon addition of PH(CH2CH2CN)2 to trans-[PtHCl(tcep)2] in the presence of base, is shown to be a catalyst precursor for the reaction of PH(CH2CH2CN)2 with CH2CHCN. Two parallel mechanisms involving mononuclear and binuclear intermediates are discussed to rationalise these observations.
铂(0)配合物 [Pt(tcep)3](tcep = P(CH2CH2CN)3)催化 PH3 和 CH2CHCN 生成 tcep。比较了[M(tcep)3](M =
铂、
钯或
镍)和[MCl(tcep)3](M =
铑或
铁)催化 PH(CH2CH2CN)2 与 CH2CHCN 反应生成 tcep 的情况,结果表明
铂(0)配合物的催化效率最高。通过 31P-1H} NMR 光谱监测动力学,对
铂(0)的催化作用进行了详细研究。核磁共振光谱对动力学进行了监测。研究表明,动力学是产物 tcep 浓度的复杂函数。从定性角度看,速率还取决于 [CH2CHCN] 和 [催化剂]。31P-1H}和 195Pt-1H}核磁共振光谱表明,在 [Pt(tcep)3] 中加入 CH2CHCN 会产生复合物 [Pt(tcep)2(η2-CH2CHCN)],该复合物会在核磁共振时间尺度上发生膦交换。双核[Pt2H2(tcep)2µ-P(CH2CH2CN)2}2]是在碱存在下将 PH(CH2CH2CN)2 加入反式[PtHCl(tcep)2]后形成的,它是 PH(CH2CH2CN)2 与 CH2CHCN 反应的催化剂前体。讨论了涉及单核和双核中间体的两种并行机制,以合理解释这些观察结果。