A Kinetic Study on the Substitution for Acetonitrile at the trans-to-μ-Oxido Sites in a Bis(μ-acetato)(μ-oxido)diruthenium(III) Dipositive Complex: Dissociative–Associative Transition of the Activation Mode for the Substitution of Pyridine Derivatives
A Kinetic Study on the Substitution for Acetonitrile at the trans-to-μ-Oxido Sites in a Bis(μ-acetato)(μ-oxido)diruthenium(III) Dipositive Complex: Dissociative–Associative Transition of the Activation Mode for the Substitution of Pyridine Derivatives
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双(μ-乙酰基)(μ-氧化)二钌(III)二正配合物中乙腈反式μ-氧化位点取代的动力学研究：取代的激活模式的解离-缔合转变吡啶衍生物
DOI：
10.1002/ejic.201300173
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发表时间：
2013
影响因子：
2.3
通讯作者：
A. Nagasawa
中科院分区：
文献类型：
--
作者：
Y. Ido;K. Sakaguchi;M. Tasei;S. Minami;H. Sawamoto;T. Fujihara;A. Nagasawa
合成了一种新的二Ru(III)配合物[[RuIII2(μ‐O)(μ‐CH3CO2)2(bpy)2(CH3CN)2](PF6)2[1(PF6)2，bpy=2，2‘-联吡啶]，并用1HNMR和UV/Vis光谱研究了在0.101-147MPaCH3CN中，0-60℃温度下CH3CN氧化为μ-位的动力学行为。在5℃下，Cd_3CN溶液中的溶剂交换得到反应速率常数k=2.43 × 10~(-3)s~(-1)，活化参数ΔH‡=124kJ ~(-1)，ΔS‡=+150J K~(-1)，属于解离机理(IDOR D)。在30℃下，吡啶(Py)在Cd_3CN中的取代反应生成[RuIII2(μ‐O)(μ‐CH3CO2)2(bpy)2(py)2](PF6)2[2a(PF6)2]，，其每个位置的速率常数K=1.56 × 10~(-2)m~(-1)s~(-1)，活化参数ΔH‡=81kJ m ol~(-1)和ΔS‡=-13 J K~(-1)m ol~(-1)。不同的吡啶类化合物取代CH_3CN in_1(Pf_6)_2的活化参数不同：ΔH‡为66~92 kJ m ol~(-1)。ΔS的‡范围为-51~+22J K~(-1)，ΔV‡(R=H，3-Ac，4-NH_2，4-CN，3-CN为R=H，3-Ac，4-NH_2，4-CN，3-CN)范围为+1.3cm~(-3)~+3.2cm~3mol~(-1)。ΔH‡和ΔS‡之间存在补偿效应，且两者都与Hammett参数呈线性关系。取代基R电子影响Rpy与Ru中心在过渡态的相互作用强度，使活化模式向解离(ID)或缔合(Ia)交换转变。
A new diruthenium(III) complex [RuIII2(μ‐O)(μ‐CH3CO2)2(bpy)2(CH3CN)2](PF6)2[1(PF6)2, bpy = 2,2′‐bipyridine] has been synthesized, and the dynamic behaviour of CH3CN at thetrans‐to‐μ‐oxido sites were investigated by1H NMR and UV/Vis spectroscopy at 0–60 °C under 0.101–147 MPa in CH3CN. The solvent exchange in CD3CN at 5 °C gave the rate constantk= 2.43 × 10–3s–1and the activation parameters ΔH‡= 124 kJ mol–1and ΔS‡= +150 J K–1mol–1, which point to a dissociative mechanism (Idor D). The ligand substitution of pyridine (py) in CD3CN at 30 °C, yielding [RuIII2(μ‐O)(μ‐CH3CO2)2(bpy)2(py)2](PF6)2[2a(PF6)2], gave a rate constant per site ofk= 1.56 × 10–2M–1s–1, and the activation parameters ΔH‡= 81 kJ mol–1and ΔS‡= –13 J K–1mol–1. The substitution of various pyridine derivatives (Rpy) for CH3CN in1(PF6)2exhibited varying activation parameters: ΔH‡ranged from 66 to 92 kJ mol–1, ΔS‡ranged from –51 to +22 J K–1mol–1, and ΔV‡(for Rpy with R = H, 3‐Ac, 4‐NH2, 4‐CN, 3‐CN) ranged from +1.3 to +3.2 cm3mol–1. These results suggest an interchange (I) mechanism for the substitution of Rpy, for which its strong electron‐donating ability is responsible. A compensation effect is seen between ΔH‡and ΔS‡, and both have linear relationships with the Hammett parameters. The substituent R electronically influences the strength of the interaction of Rpy with Ru center in the transition state to shift the activation mode to a dissociative (Id) or an associative (Ia) interchange.