二氯三苯基磷的能量、红外及拉曼光谱、化学位移和耦合常数的量子化学研究

采用密度泛函理论(DFT)B3LYP/6-31G**方法研究了二氯三苯基磷在分子势能超曲面上的4种稳定结构,计算了结构Ⅰ-Ⅳ的能量、红外及拉曼光谱、原子的化学位移和耦合常数,并作了频率分析,确认存在离子态的四配位磷化合物和三角双锥型的五配位磷化合物.结构Ⅰ,Ⅲ,Ⅳ是能量的最低点,没有虚频,结构Ⅱ有一个虚频,是一鞍点的过渡态,鞍点结构具有Cl—P—Cl三重轴,3个苯环共平面,结构Ⅲ也有Cl—P—Cl三重轴,苯环呈扭曲螺旋状,能量最低,结构Ⅰ呈离子态、松散状结构,结构Ⅳ呈尖塔状,苯基取螺旋型,为四配位闸型结构,是一复杂的电荷转移体.

Study on Quantum Chemistry of Energies, Infrared Spectroscopy (IR), Raman Spectroscopy, the Chemical Shift of All the Atoms and Coupled Constant of Triphenyldichlorophosphorane

The geometries of triphenyldichlorophosporane are optimized,and four stable conformations are found by using DFT B3LYP/6-31G** method.The electronic structures,energies,infrared spectroscopy(IR),Raman spectroscopy,nuclear magnetic resonance spectroscopy(NMR),the chemical shift of all the atoms,and the coupled constants of the stable conformations I to IV are calculated at DFT B3LYP/6-31G** level.The triphenydichlorophosphorane exists in four-coordinated Ph3PCl2 and five-coordinated compound(trigonal bipyramidal) forms.The conformations I,III and IV are the minima,having no imaginary frequency.However,the conformation II is a transition state with one imaginary frequency,which is a third-order saddle point,in which the three phenyl groups are coplanar.The conformation I is a structure with loosely bound ion-pair between a pyramidal cation Ph3PCl and a Cl-anion,and the three phenyl rings are twisted.Structure IV is pyramidal and has twisted phenyl rings.