二氯亚锗基卡宾与甲醛生成锗杂双环化合物反应的从头算研究

用CCSD(T)//MP2/6-31G^*方法研究了单重态二氯亚锗基卡宾(Cl₂Ge=C:)与甲醛生成锗杂双环化合物的环加成反应机理,根据该反应的势能面可以预言,该反应有两条相互竞争的主反应通道．该反应所呈现的反应规律为：二氯亚锗基卡宾中C原子的2p空轨道因从氧端插入甲醛的π轨道而造成了中间体的形成;在中间体和两反应物之间,因二氯亚锗基卡宾和甲醛中的两成键π轨道发生了[2+2]环加成作用,从而分别生成了Ge-O对位的和Ge-O顺位的两四元环化合物;由于四元环化合物中卡宾C原子的不饱和性,进一步与甲醛作用,从而生成了两锗杂双环化合物．     

Theoretical Study on the Effects of Spatial Structure of P Complexation Sites on the Soil Phosphorus Activation in Leonardite Humic Acid Complexes

Humic acid is an important active component in soil environment. The spatial structures of P complexation sites in humic acid complexes play an important role in soil phosphorus activation and fertilizer efficiency. To explore the effects of spatial structure, the three different coordination modes of iron-carboxyl in models were calculated by the ONIOM method available in the Gaussian09 package. The(U)B3LYP hybrid density functional was employed to optimize the configuration for the QM region, and the UFF force field was used to calculate for the MM region. The results show that the different spatial structures influence the soil phosphorus activation by affecting the electronic structure, Gibbs free energy and interaction energy of the models. And the effects are as follows: the unidentate structure model ~6P-Fe-MHA-UD, the bidentate chelating structure model ~6P-Fe-MHA-BD>the bidentate bridging structure model ~5P-Fe-MHA-BD-BG. It can be known that, the fertilizer efficiency can be improved through increasing the proportion of the unidentate structure and the bidentate chelating structure in production engineering. The research provides a theoretical basis for further optimization of the production of humic acid phosphate fertilizer.     

亚锗基卡宾及取代亚锗基卡宾与环氧乙烷抽提反应机理的密度泛函理论研究

采用B3LYP/6-311G(d,p)方法研究了单重态亚锗基卡宾及取代亚锗基卡宾X₂Ge=C:(X=H, F, Cl, CH₃)与环氧乙烷的氧转移反应机理. 结果表明, 由于环氧乙烷中氧上的2p孤对电子向X₂Ge=C:中C上的2p空轨道迁移,形成了p→p授受键,从而生成了各中间体. 随着p→p授受键的不断加强(即C-O键的逐渐缩短),中间体经过渡态生成了抽提产物. 取代基的电负性是影响该类反应的主要因素,取代基的电负性越大,反应的活化能越小