手性氮磷配体与钌的配位过程的研究—原位变温^(31)P核磁及分子模拟计算

The Study of Coordinate Process of Chiral Diiminodiphophine Ligand with Ruthenium by in situ Variable Temperature ^(31)P NMR and Computer Modeling

用原位变温31PNMR和分子模拟研究了手性氮磷配体与金属钌的配位过程。首先确定了配体及其与金属的配合物的化学位移信号分别在δ=-13.0ppm和δ=48.2ppm。配位过程在293～343K温度范围内,相继生成四配位和五配位中间体。四配位体在31PNMR上对应于30.8ppm和-15.0ppm的两个信号;五配位中间体对应于35.1ppm和-16.5ppm的两个信号;最后在343K,产物中只有六配位的配合物存在,其信号出现在48.2ppm。为了得到各种中间体的结构,用分子模拟方法进行了结构优化计算,并比较了它们的构象能。计算结果表明,四配位中间体有两种构象,能量相差9kcal·mol-1,它们可能同时存在于平衡状态。而五配位中间体只有一种绝对优势构象,尚有一个磷原子未参与配位。六配位的钌金属配合物的结构优化结果显示,两个氯原子分别位于PNNP原子所构成平面的两侧。其构象能为162.0kcal·mol-1,其中键角能的贡献是112.5kcal·mol-1,而非键静电作用是-41.4kcal·mol-1,这表明分子内的静电吸引力对于形成完全配位产物是十分有利的,但是收敛的配体分子却承受了较大的键角张力。

The coordinate process of Chiral Diiminodiphophine Ligand with Ruthenium is investigated with in situ variable temperature 31P NMR and computer modeling. At first the chemical shifts of ligand and the six coordinated complex are determined at -13.0ppm and 48.2ppm, respectively. During the coordinate process at the temperature between 293K and 313K, the four and five coordinated intermediates are produced one after the other. The four coordinated intermediate has two signals at 30.8ppm and -15.0ppm, and the five coordinated intermediate has two peaks at 35.1ppm and -16.5ppm. At 343K only the six coordinated complex is found in the product, it's signal appears at 48.2ppm. Molecular modeling is used to show their conformations. All coordinated complexes are constructed and optimized with molecular mechanics and molecular dynamics. The calculation results show that the four coordinated complex has two conformers with an energy difference of 9kcal·mol-1, which are in equilibrium. The five coordinated intermediate has only one preferred conformation with a single uncoordinated P atom. The calculated construction of six coordinated complex reveals that two chloride atoms located on both sides perpendicular to the planar consisted from PNNP atoms. The conformation energy is 162.0kcal·mol-1, to which the bond angle energies contribute 112.5kcal·mol-1, and the electrostatic energy is -41.4kcal·mol-1. This means that the electrostatic interactions are benefit to producing completely coordinate product. At the same time the convergent ligand molecule bears larger bond angle torsions.