【摘要】 分别研究了在干燥THF及H2 O/THF条件下CO2 与TpRu(PPh3 ) (CH3 CN)H [Tp =Hydrotris(pyrazolyl)borate]的反应 ,发现水对CO2 插入TpRu(PPh3 ) (CH3 CN)H的反应具有显著促进作用 .原位高压1H ,3 1P和13 C核磁共振研究显示 ,在水存在下 ,CO2 插入Ru—H键形成水合甲酸盐配合物TpRu(PPh3 ) (CH3 CN) ( η1 OCHO)·H2 O ,其中甲酸盐配体与溶剂中水分子形成分子间氢键 .在B3LYP水平上的密度泛涵理论计算表明 ,在过渡态 ,CO2 分子中碳原子的亲电性由于其氧原子与水分子形成氢键而得到增强 ,进而显著降低CO2 插入TpRu(PPh3 ) (CH3 CN)H中Ru—H键的活化能 .TpRu(PPh3 ) (CH3 CN) ( η1 OCHO)·H2 O很快部分转化为另一甲酸盐配合物TpRu(PPh3 ) (H2 O) ( η1 OCHO) ,二者最后达成平衡 ,后者由于甲酸盐配体与水分子配体间形成分子内氢键而稳定更多还原

【Abstract】 A promoting effect of water on CO 2 insertion into TpRu(PPh 3)(CH 3CN)H [Tp=Hydrotris(pyrazolyl)borate] is observed. In situ high pressure 1H, 31 P and 13 C NMR monitoring shows that CO 2 readily inserts into Ru-H to form the hydrated metal formate TpRu(PPh 3)(CH 3CN)(η 1 OCHO)·H 2O in which the formate ligand is intermolecularly H bonded to a water molecule. Theoretical calculations carried out at the B3LYP level show that electrophilicity of the carbon center of CO 2 is enhanced by the formation of H bonds between its oxygen atoms and H 2O in the transition state of the process, and thus reaction barrier of the CO 2 insertion is significantly reduced in the presence of water. The hydrated formate species TpRu(PPh 3)(CH 3CN)(η 1 OCHO)·H 2O comes into equilibrium rapidly with another metal formate species TpRu(PPh 3)(H 2O)(η 1 OCHO), in which the coordinated H 2O is intramolecularly H bonded with the formate ligand.更多还原