A deeper look into thiophene coordination prior to oxidative addition of the C-S bond to platinum(0):: A computational study using DFT and MO methods
A deeper look into thiophene coordination prior to oxidative addition of the C-S bond to platinum(0):: A computational study using DFT and MO methods
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DOI：
10.1021/om700679j
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发表时间：
2008-01-14
期刊：
影响因子：
2.8
通讯作者：
Jones, William D.
中科院分区：
文献类型：
--
作者：
Atesin, Tuelay A.;Jones, William D.
噻吩与零价铂双烷基膦片段的反应产生由C-S键断裂衍生的高度稳定的硫铂并噻吩。使用密度泛函理论对[Pt（dmpe）]模型系统的计算与用[Pt（dippe）]获得的实验结果一致，因为反应总体上是放热的，并且进一步预测噻吩通过C = C双键的初始eta（2）-配位比通过硫原子的配位在能量上更有利（Δ G = 9.3 kcal/mol）。有三个明确的过渡态沿着的途径，从这两种配位模式的氧化加成产物。其中两个导致更高能量的η（2）-C，S-配位中间体，而第三个导致C-S键从η（2）-C，S络合物裂解。由于反应是在极性溶剂（THF）中进行的，溶剂化的影响通过使用极化连续模型来考虑。噻吩通过C = C键的初始配位的热力学偏好被发现在THF中更大（Δ G = 11.4 kcal/mol）。更重要的是，从C = C配位络合物的过渡态的总自由能现在低于溶液中的S-配位络合物。因此，噻吩通过C = C双键的初始eta（2）-配位导致动力学优选途径。进行了分子轨道分析，以合理化的结果。
The reaction of thiophene with a zerovalent platinum bisalkylphosphine fragment yields a highly stable thiaplatinacycle derived from cleavage of the C - S bond. Calculations on the [Pt(dmpe)] model system using Density Functional Theory are consistent with experimental results obtained with [Pt(dippe)] in that the reaction is exothermic overall and furthermore predict that the initial eta(2)-coordination of thiophene through the C = C double bond is energetically more favorable than coordination through the sulfur atom (Delta G = 9.3 kcal/mol). There are three well-defined transition states along the pathway to the oxidative addition product from both of these coordination modes. Two of these lead to a higher energy eta(2)-C,S-coordinated intermediate, while the third one leads to cleavage of the C - S bond from the eta(2)-C,S complex. As the reaction was carried out in a polar solvent (THF), the effect of solvation was taken into account by using the polarizable continuum model. The thermodynamic preference for the initial coordination of thiophene through the C = C bond is found to be greater in THF (Delta G = 11.4 kcal/mol). More importantly, the total free energy of the transition state from the C = C coordinated complex is now lower than that of the S-coordinated complex in solution. Therefore, the initial eta(2)-coordination of thiophene through the C = C double bond results in the kinetically preferred pathway. Molecular orbital analyses were carried out to rationalize the results.