单氢钌配合物催化氢化苯乙烯的位阻效应  

Steric Hindrance Effect on Hydrogenation of Styrene Catalyzed by Ruthenium Hydride Complex

作　　者：尹传奇[1] 冯权武[1] 柏正武[1] 

机构地区：[1]武汉工程大学绿色化工过程省部共建教育部重点实验室,武汉430074

出　　处：《化学学报》2009年第6期519-522,共4页Acta Chimica Sinica

基　　金：湖北省自然科学基金(No.2006ABA282);湖北省教育厅基金(No.D200615005)资助项目

摘　　要：研究了溶剂分别为THF,H2O/THF,CH3CN/THF以及ROH/THF(R=Me,Et,iso-Pr,tert-Bu)条件下TpRuH(PPh3)-(CH3CN)[Tp=hydrotris(pyrazolyl)borate]催化氢化苯乙烯生成乙基苯的反应,发现向干燥THF体系中添加微量H2O,CH3CN或ROH对催化反应都具有显著的促进作用.催化机理研究表明,小分子添加物首先取代TpRuH(PPh3)(CH3CN)中的PPh3配体形成中间体TpRuH(CH3CN)L(L=H2O,CH3CN或ROH),降低空间位阻,CH3CN配体随后被苯乙烯取代生成中间体TpRuH(H2C=CHPh)L;η2-苯乙烯插入Ru—H键后形成的Ru-烷基中间物与H2反应生成η2-H2配合物TpRu(CH2CH2Ph)(H2)L或TpRu[CH(CH3)Ph](H2)L,进而发生σ-复分解反应生成乙基苯完成催化循环.Hydrogenation of styrene catalyzed by TpRuH（PPh3）（CH3CN） [Tp = hydrotris（pyrazolyl）borate] with THF, H2O/THF, CH3CN/THF and ROH/THF （R=Me, Et, iso-Pr, tert-Bu） as solvents was studied, respectively. It was found that addition of trace amount of small molecule H2O, CH3CN or ROH in anhydrous THF effectively promoted the catalytic reaction. The catalytic mechanism is proposed that PPh3 ligand in TpRuH（PPh3）（CH3CN） is first replaced by H2O, CH3CN or ROH to form intermediates TpRuH（CH3CN）L （L = H20, CH3CN or ROH） to reduce the steric hindrance of PPh3, and CH3CN is then replaced by styrene to produce TpRuH（H2C = CHPh）L. The insertion of η^2-styrene into the Ru-H bond followed by reaction with H2 leads to the formation of Ru-alkyl intermediates TpRu（CH2CH2Ph）（H2）L and TpRu[CH（CH3）Ph]（H2）L. Intramolecular protonation of the adjacent alkyl ligand by an η^2-H2 ligand produces ethylbenzene to fulfill the catalytic cycle.

关 键 词：苯乙烯 位阻 催化氢化 单氢钌配合物 

分 类 号：O643.31[理学—物理化学]