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

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

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.

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 BSLYP/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.