Theoretical calculations of the [2,3]-sila-wittig rearrangement of isomers of [（allyloxy）silyl]lithium （C3H5O）HzSiLi have been performed in the gas phase and THF solvent using the G3MP2B3 method. Seven isomers of ...Theoretical calculations of the [2,3]-sila-wittig rearrangement of isomers of [（allyloxy）silyl]lithium （C3H5O）HzSiLi have been performed in the gas phase and THF solvent using the G3MP2B3 method. Seven isomers of silylenoid （C3H5O）H2SiLi, 1-7, are found. The [2,3]-silawittig rearrangement paths are followed using two isomers, 2 and 4, to yield the transition states as well as the products. In the transition state, the silicon center functions as a nucleophile and the aUyl as an electrophile. The interaction between the silicon and allylic sites leads to the formation of SiC（3） bond and the break of O-C（1） bond. Finally, the （allylsilyl）oxylithium （C3H5）H2SiOLi is obtained. The rearrangement paths are confirmed by the intrinsic reaction coordinate （IRC） calculations. The rearrangement mechanisms of reactions of 2 and 4 are similar, and the latter reaction is more favored in the gas phase and THF solvent. Also, the solvent effects are analyzed in this work.展开更多
Quantum chemical calculations were carried out to investigate the structures and properties for the inclusion complexes of nitrobenzene （NB） into β-cyclodextrin. Two low-energy conformations of β-cyclodextrin （A ...Quantum chemical calculations were carried out to investigate the structures and properties for the inclusion complexes of nitrobenzene （NB） into β-cyclodextrin. Two low-energy conformations of β-cyclodextrin （A and B） in the gas phase were initially investigated by the PM3 and B3LYP/6-31＋G（d,p） calculations, respectively. Three different orientations were considered in the inclusion process of A and B with NB to form 1：1 complexes. Potential energy scan by PM3 calculations indicated that the phenyl orientation Ab for conformation A and the equator orientation Bc for conformation B are more favorable in energy, respectively. We also considered the 2：1 inclusion complexes of host A or B with guest NB in the gas phase. PM3 calculation indicated that the host-guest interaction energies to form 1：1 complexes are more negative than those to form 2：1 NB/B complexes. Finally, we studied the solvent effect of NB/CD complex, and PM3 results show that the influence of water molecules on the inclusion process is very important. The driving forces for the inclusion process and the geometries of complexes were discussed in detail.展开更多
基金PhD Special Research Foundation of Chinese Education Department (No. 20040422010)the Scientific Research Foundation of Yangzhou University
文摘Theoretical calculations of the [2,3]-sila-wittig rearrangement of isomers of [（allyloxy）silyl]lithium （C3H5O）HzSiLi have been performed in the gas phase and THF solvent using the G3MP2B3 method. Seven isomers of silylenoid （C3H5O）H2SiLi, 1-7, are found. The [2,3]-silawittig rearrangement paths are followed using two isomers, 2 and 4, to yield the transition states as well as the products. In the transition state, the silicon center functions as a nucleophile and the aUyl as an electrophile. The interaction between the silicon and allylic sites leads to the formation of SiC（3） bond and the break of O-C（1） bond. Finally, the （allylsilyl）oxylithium （C3H5）H2SiOLi is obtained. The rearrangement paths are confirmed by the intrinsic reaction coordinate （IRC） calculations. The rearrangement mechanisms of reactions of 2 and 4 are similar, and the latter reaction is more favored in the gas phase and THF solvent. Also, the solvent effects are analyzed in this work.
基金Supported by the National Natural Science Foundation of China (No. 20773107, 20877049)China Postdoctoral Science Foundation (No. 20080431123)Jiangsu Planned Projects for Postdoctoral Research Funds (No. 0801020C)
文摘Quantum chemical calculations were carried out to investigate the structures and properties for the inclusion complexes of nitrobenzene （NB） into β-cyclodextrin. Two low-energy conformations of β-cyclodextrin （A and B） in the gas phase were initially investigated by the PM3 and B3LYP/6-31＋G（d,p） calculations, respectively. Three different orientations were considered in the inclusion process of A and B with NB to form 1：1 complexes. Potential energy scan by PM3 calculations indicated that the phenyl orientation Ab for conformation A and the equator orientation Bc for conformation B are more favorable in energy, respectively. We also considered the 2：1 inclusion complexes of host A or B with guest NB in the gas phase. PM3 calculation indicated that the host-guest interaction energies to form 1：1 complexes are more negative than those to form 2：1 NB/B complexes. Finally, we studied the solvent effect of NB/CD complex, and PM3 results show that the influence of water molecules on the inclusion process is very important. The driving forces for the inclusion process and the geometries of complexes were discussed in detail.
