二氧化碳插入单氢钌配合物反应中的水效应研究

分别研究了在干燥THF及H2O/THF条件下CO2与TpRu(PPh3)(CH3CN)H Tp=Hydrotris(pyrazolyl)borate]的反应,发现水对CO2插入TpRu(PPh3)(CH3CN)H 的反应具有显著促进作用.原位高压^1H,^31P和^13C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)(CH3CN)(η^1-OCHO)·H2O键而 得到增强,进而显著降低CO2插入TpRu(PPh3)(CH3CN)H中Ru-H键的活化能。TpRu (PPh3)(CH3CN)(η^1-OCHO)·H2O很快部分转化为另一甲酸盐配合物TpRu(PPh3)（ H2O）(η^1-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。

Study on Effect of Water in CO_2 Insertion into Ruthenium Hydride Complex

A promoting effect of water on CO2 insertion into TpRu(PPh3) (CH3CN) H Tp = Hydrotris(pyrazolyl) borate] is observed. In situ high-pressure 1H, 31P and 13C NMR monitoring shows that CO2 readily inserts into Ru- Hto form the hydrated metal formate TpRu (PPh3) (CH3CN) (-n'-OCHO) ? H2O 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 CO2 is enhanced by the formation of H-bonds between its oxygen atoms and H2O in the transition state of the process, and thus reaction barrier of the CO2 insertion is significantly reduced in the presence of water. The hydrated formate species TpRu(PPh3) (CH3CN) (η'-OCHO) ? H20 comes into equilibrium rapidly with another metal formate species TpRu(PPh3) (H2O) (η'-OCHO), in which the coordinated H2O is intramolecularly H- bonded with the formate ligand.