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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Structure and dynamics of binary and ternary lanthanide(iii) and actinide(iii) tris[4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione] (TTA) complexes. Part 2, the structure and dynamics of binary and ternary complexes in the Y(iii)/Eu(iii) -TTA - Tributylphosphate (TBP) system in chloroform as studied by NMR spectroscopy
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Structure and dynamics of binary and ternary lanthanide(iii) and actinide(iii) tris[4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione] (TTA) complexes. Part 2, the structure and dynamics of binary and ternary complexes in the Y(iii)/Eu(iii) -TTA - Tributylphosphate (TBP) system in chloroform as studied by NMR spectroscopy

机译：二和三价镧系元素（iii）和act系元素（iii）三[4,4,4-三氟-1-（2-噻吩基）-1,3-丁二酮]（TTA）配合物的结构和动力学。第2部分，通过NMR光谱研究了氯仿中Y（iii）/ Eu（iii）-TTA-磷酸三丁酯（TBP）系统中二元和三元配合物的结构和动力学

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The stoichiometric reaction mechanisms, rate constants and activation parameters for inter- and intramolecular ligand exchange reactions in the binary Y/Eu(TTA)_3(OH_2)_2-HTTA and the ternary Y/Eu(TTA)_3(OH_2)_2-TBP systems have been studied in chloroform using ~1H and ~(31)P NMR methods. Most complexes contain coordinated water that is in very fast exchange with water in the chloroform solvent. The exchange reactions involving TTA/HTTA and TBP are also fast, but can be studied at lower temperature. The rate constant and activation parameters for the intramolecular exchange between two structure isomers in Y(TTA)_3(OH_2)_2 and Y(TTA)_3(TBP) (OH_2) were determined from the line-broadening of the methine protons in coordinated TTA. The rate equations for the intermolecular exchange between coordinated TTA and free HTTA in both complexes are consistent with a two-step mechanism where the first step is a fast complex formation of HTTA, followed by a rate determining step involving proton transfer from coordinated HTTA to TTA. The rate constants for both the inter- and intramolecular exchange reactions are significantly smaller in the TBP system. The same is true for the activation parameters in the Y(TTA)_3(OH_2)_2-HTTA and the ternary Y/Eu(TTA)_3(TBP)(OH_2)-HTTA systems, which are ΔH~≠ = 71.8 ± 2.8 kJ mol~(-1), ΔS ~≠ = 62.4 ± 10.3 J mol~(-1) K~(-1) and ΔH~≠ = 38.8 ± 0.6 kJ mol~(-1), ΔS ~≠ = -93.0 ± 3.3 J mol~(-1) K~(-1), respectively. The large difference in the activation parameters does not seem to be related to a difference in mechanism as judged by the rate equation; this point will be discussed in a following communication. The rate and mechanism for the exchange between free and coordinated TBP follows a two-step mechanism, involving the formation of Y(TTA)_3(TBP)_2.
机译：二元Y / Eu（TTA）_3（OH_2）_2-HTTA和三元Y / Eu（TTA）_3（OH_2）_2-TBP中分子间和分子内配体交换反应的化学计量反应机理，速率常数和活化参数已使用〜1H和〜（31）P NMR方法在氯仿中研究了这些系统。大多数配合物都包含配位水，该配位水与氯仿溶剂中的水非常快速地交换。涉及TTA / HTTA和TBP的交换反应也很快，但是可以在较低的温度下进行研究。 Y（TTA）_3（OH_2）_2和Y（TTA）_3（TBP）（OH_2）中两个结构异构体之间分子内交换的速率常数和激活参数由配位TTA中次甲基质子的线宽确定。两种络合物中配位的TTA与游离HTTA之间的分子间交换的速率方程与两步机理一致，其中第一步是快速生成HTTA，然后是速率确定步骤，涉及质子从配位HTTA到TTA的转移。 。在TBP系统中，分子间和分子内交换反应的速率常数都明显较小。对于Y（TTA）_3（OH_2）_2-HTTA和三元Y / Eu（TTA）_3（TBP）（OH_2）-HTTA系统中的激活参数也是如此，它们的ΔH〜≠= 71.8±2.8 kJ mol〜（-1），ΔS〜≠= 62.4±10.3 J mol〜（-1）K〜（-1）和ΔH〜≠= 38.8±0.6 kJ mol〜（-1），ΔS〜≠= -93.0分别为±3.3 J mol〜（-1）K〜（-1）。激活参数的巨大差异似乎与速率方程判断的机制差异无关;这一点将在下面的通讯中讨论。自由和协调的TBP之间的交换速率和机制遵循两步机制，涉及Y（TTA）_3（TBP）_2的形成。

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