Twists and Turns of Platinum-Allene Complexes: NMR Techniques for the Study of the Dynamic Behavior in Solution

Classic (dynamic exchange line-shape analysis) and novel (SSTD NMR) NMR techniques have been applied in order to obtain the kinetic and thermodynamic parameters of the three main processes occurring in the fluxional behavior of Pt-allene complexes with N-containing ligands, in four and five coordination mode, in solution. Our results show intramolecular helical and rotational movements closely related to each other, confirming η1-staggered structures as possible intermediates. The ligand exchange in these complexes seems to occur via a ligand-independent dissociative mechanism, where coordinating solvents might be involved in the stabilization of the intermediates. The differences observed in the interaction of allenes with other metals could be the basis to explain the divergent reactivity observed in platinum-catalyzed processes.本研究采用经典的动态交换线型分析（dynamic exchange line-shape analysis）与新型的SSTD NMR核磁共振技术，以获取溶液中具有四配位与五配位模式的含氮配体铂-丙二烯配合物的流变行为相关的三类主要过程的动力学与热力学参数。研究结果表明，分子内螺旋运动与旋转运动紧密相关，证实η1-交错构型可作为潜在反应中间体。此类配合物中的配体交换似乎通过配体非依赖型解离机理进行，配位溶剂可能参与中间体的稳定过程。丙二烯与其他金属的相互作用所呈现的差异，或可作为解释铂催化反应中观测到的各异反应活性的基础。