廉价金属配合物催化氢化烯烃反应机理的理论研究
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- 英文论文题名：Mechanistic Insights on Directed Alkene Hydrogenation Catalyzed by Bis(phosphine)cobalt Dialkyl Complexes:A DFT Study
- 论文作者：马雪璐 ; 雷鸣 ; Paul J.Chirik ; 何静
- 英文论文作者：Xuelu Ma ; Ming Lei ; Paul J.Chirik ; Jing He ; State Key Laboratory of Chemical Resource Engineering ; Beijing University of Chemical Technology ; Department of Chemistry ; Princeton University
- 年：2016
- 作者机构：北京化工大学化工资源有效利用国家重点实验室;Department of Chemistry, Princeton University;
- 论文关键词：廉价金属 ; 烯烃氢化 ; 反应机理 ; 密度泛函
- 会议召开时间：2016-07-01
- 会议录名称：中国化学会第30届学术年会摘要集-第四十五分会：物理有机
- 语种：中文
- 分类号：O621.251
- 学会代码：ZGHY
- 会议名称：中国化学会第30届学术年会-第四十五分会 ; 物理有机
- 会议地点：中国辽宁大连
- 主办单位：中国化学会
- 学会名称：中国化学会
- 页数：1
- 文件大小：242k
- 原文格式：D
- 会议级别：全国
摘要
本文采用密度泛函的方法研究双膦配体Co(Ⅱ)催化烯烃氢化反应的反应机理,结合实验结果,阐明烯烃底物官能团对产率影响的具体细节,明确廉价金属催化剂在催化不同类型烯烃底物的特异性。计算结果表明,该反应以T型结构的(diphosphine)CoH_2(0~T)为催化活性组分,包括四个基元反应步骤:(1)烯烃配位放热,(2)烯烃迁移插入Co-H键,(3)第二分子氢气配位,和(4)σ键置换最终得到烷烃产物。其中第(4)步是决速步骤。在烯烃插入中,1,2-烯烃插入(反马氏加成)要优于2,1-烯烃插入(马氏加成)。计算表明立体位阻大的烯烃底物在氢化中的反应活性较低,与实验结果一致。此外,通过调变过渡金属中心,比较了Fe,Ru,Os,Co,Rh,Ir对烯烃氢化反应的影响,提出决定烯烃氢化产物的立体选择性规律。并对四种不同立体位阻底物进行整体分析,计算结果表明Fe、Ir和Co的催化氢化活性要优于Ru、Rh和Os。且除Co以外的金属活化不同位阻底物的顺序相同,说明Co催化剂对于氢化不同烯烃底物的活性具有特异性。
The mechanism of directed alkene hydrogenation catalyzed by bis(phosphine)cobalt dialkyl complexes first reported by Chirik et al has been studied by means of density functional theory calculations. The calculations suggest that the reaction involves a Co~Ⅱ catalytic cycle facilitated by coordination of a second H_2. The catalytic cycle begins with a T-shaped(diphosphine)CoH_2 that coordinates and inserts the alkene, followed by the coordination of a second equivalent of H_2. The resulting Co~Ⅱ intermediate undergoes a rate-de termining σ bond metathesis step. Furthermore, 1,2-insertion of alkene into the Co-H bond is preferred over the 2,1-insertion. The effect of transition-metal modulation on the activity of olefin hydrogenation catalyst is clarified. The different valence and effect of metal centers in the olefin hydrogenation reaction mechanism are compared. The law of stereoselectivity of olefin hydrogenated products is put forward. Combined with the experimental results, functional groups in olefins substrate impacting on the yield is specified.
The mechanism of directed alkene hydrogenation catalyzed by bis(phosphine)cobalt dialkyl complexes first reported by Chirik et al has been studied by means of density functional theory calculations. The calculations suggest that the reaction involves a Co~Ⅱ catalytic cycle facilitated by coordination of a second H_2. The catalytic cycle begins with a T-shaped(diphosphine)CoH_2 that coordinates and inserts the alkene, followed by the coordination of a second equivalent of H_2. The resulting Co~Ⅱ intermediate undergoes a rate-de termining σ bond metathesis step. Furthermore, 1,2-insertion of alkene into the Co-H bond is preferred over the 2,1-insertion. The effect of transition-metal modulation on the activity of olefin hydrogenation catalyst is clarified. The different valence and effect of metal centers in the olefin hydrogenation reaction mechanism are compared. The law of stereoselectivity of olefin hydrogenated products is put forward. Combined with the experimental results, functional groups in olefins substrate impacting on the yield is specified.
引文
[1]Friedfeld,M.R.;Shevlin,M.;Hoyt,J.M.;Krska,S.W.;Tudge,M.T.;Chirik,P.J.Science 2013,342,1076-1080.
[2]Friedfeld,M.R.;Margulieux,G.W.;Schaefer,B.M.;Chirik,P.J.J.Am.Chem.Soc.2014.136,13178-13181.
[3]Ma,X.;Lei,M;Liu,S.Organometallics.2015,34,1255-1263
[2]Friedfeld,M.R.;Margulieux,G.W.;Schaefer,B.M.;Chirik,P.J.J.Am.Chem.Soc.2014.136,13178-13181.
[3]Ma,X.;Lei,M;Liu,S.Organometallics.2015,34,1255-1263