NMR and INS Line Shapes of Transition Metal Hydrides in the Presence of Coherent and Incoherent Dihydrogen Exchange
NMR and INS Line Shapes of Transition Metal Hydrides in the Presence of Coherent and Incoherent Dihydrogen Exchange
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相干和非相干二氢交换存在下过渡金属氢化物的 NMR 和 INS 谱线形状
DOI：
10.1021/ja962903r
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发表时间：
1998
影响因子：
15
通讯作者：
J. Eckert
中科院分区：
文献类型：
--
作者：
H. Limbach;S. Ulrich;Stephan Gründemann;G. Buntkowsky;S. Sabo;B. Chaudret;G. Kubas;J. Eckert
本文基于Alexander−Binsch 的量子力学密度矩阵形式，提出了相干和非相干二氢交换对过渡金属氢化物NMR 和INS 光谱影响的统一描述。线形分析的动态参数是相干交换的交换耦合或旋转隧道分裂J和非相干交换的速率常数k。作为实验示例，我们报告了 1 == Cp*RuH3(PCy3)（Cp* == C5(CH3)5 和 Cy == 环己基）的温度相关值 J 和 k，包括通过 NMR 测定的 HH/HD/DD 同位素对非相干交换的动力学影响，以及由 INS 测定的二氢钨络合物 2 ≡ W(PCy3)2 (CO)3(η-H2) 的温度依赖性值 J 和 k。 J 和 k 的温度依赖性可以根据简单的反应方案进行定性解释，该反应方案涉及每个温度下的基态和主要的振动激发态。使用形式动力学表明，激发中的相干交换......
In this paper a unified description of the effects of the coherent and incoherent dihydrogen exchange on the NMR and INS spectra of transition metal hydrides based on the quantum-mechanical density matrix formalism of Alexander−Binsch is proposed. The dynamic parameters of the line shape analyses are the exchange couplings or rotational tunnel splittings J of the coherent exchange and the rate constants k of the incoherent exchange. As experimental examples, we report the temperature dependent values J and k for 1 ≡ Cp*RuH3(PCy3) (Cp* ≡ C5(CH3)5 and Cy ≡ cyclohexyl) including the kinetic HH/HD/DD isotope effects on the incoherent exchange, determined by NMR, and for the tungsten dihydrogen complex 2 ≡ W(PCy3)2 (CO)3(η-H2), determined by INS. The temperature dependence of J and k is interpreted qualitatively in terms of a simple reaction scheme involving at each temperature a ground state and a dominant ro-vibrationally excited state. Using formal kinetics it is shown that a coherent exchange in the excite...