【摘要】 采用密度泛函B3LYP方法,在6-31++G(d,p)水平上研究和比较了HNCO与HF、HCl和HBr加成反应的反应机理.通过优化计算找到了反应的过渡态,且振动分析确认了过渡态的结构,并用内禀反应坐标方法确定了能量最低反应路径.计算结果表明3个反应都是放热反应,反应中伴随着一个σ键和一个π键断裂的同时有2个新σ键生成.过渡态是四元环结构,由于卤化氢中卤原子电负性的不同,四元环形状有比较明显的差异.过渡态最显著特征是氢原子的转移.更多还原

【Abstract】 The additional reactions of HNCO with HF,HCl and HBr have been investigated with Gaussian 03 at B3LYP/6-31++G(d,p) level.Vibration analysis is carried out to confirm its identity as a transition structure.The intrinsic reaction coordinate is performed to search the minimum energy path.The calculated result shows that three reactions belong to exothermal reactions.There are one σ bond and one π bond breaking and two new σ bonds forming in the reactions.There is a four-member ring forming in transition state.Due to the difference in electron-withdrawing ability of the atoms F,Cl and Br of HF,HCl and HBr molecules,the geometries of the four-member ring of the transition states are obviously different.The characteristic of reaction in transition state is the transfer of H atom.更多还原