Reactions of hydrogen or deuterium molecule with a rhodium(II) metalloradical: kinetic evidence for a four-centered transition state
Reactions of hydrogen or deuterium molecule with a rhodium(II) metalloradical: kinetic evidence for a four-centered transition state
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氢或氘分子与铑(II)金属自由基的反应：四中心过渡态的动力学证据
DOI：
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发表时间：
1992
期刊：
影响因子：
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通讯作者：
A. Sherry
中科院分区：
文献类型：
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作者：
B. Wayland;Sujuan Ba;A. Sherry
金属催化的底物氢化包括将氢加到金属中心作为必经步骤。这类反应的重要性促使人们努力了解H{sub2}与金属络合物反应的机理途径的范围。通过添加到一个金属中心形成二氢化合物和通过与两个金属中心反应形成一元氢化物都是常见的现象。通过动力学研究、对{eta}{sup 2}-二氢络合物的观察和理论研究，已经详细地证明了H{sub2}通过三中心三角过渡态协同加成形成二氢化合物。通过在两个金属中心上加氢而形成氢化物的研究较少，但已经认识到二氢的多步异解和协同均解裂解。本文研究了H{sub2}(D{sub2})与(TMP)Rh{sm Bullet}通过四中心过渡态生成(TMP)Rh-H的反应。
Metal-catalyzed hydrogenation of substrates involves addition of hydrogen to the metal center as an obligatory step. The importance of this class of reactions has stimulated efforts to understand the scope of mechanistic pathways operative in reactions of H{sub 2} with metal complexes. Formation of dihydrides by addition to a single metal center and monohydrides by reaction with two metal sites are both frequently observed. Concerted addition of H{sub 2} to form dihydrides through a three-centered triangular transition state has been thoroughly documented by kinetic studies, observation of {eta}{sup 2}-dihydrogen complexes, and theoretical considerations. Formation of monohydrides by addition of H{sub 2} to two metal centers is less fully investigated, but both multistep heterolytic and concerted homolytic cleavage of dihydrogen have been recognized. This article describes the reaction of H{sub 2} (D{sub 2}) with (tetramesitylporphyrinato)rhodium(II), (TMP)Rh{sm bullet}, to form (TMP)Rh-H through a four-centered transition state.