X2Si=Sn:(X = H, Me, F, Cl, Br, Ph, Ar…) are new species of chemistry. The cycloaddition reaction of X2Si=Sn: is a new study field of stannylene chemistry. To explore the rules of cycloaddition reaction between X2Si=S...X2Si=Sn:(X = H, Me, F, Cl, Br, Ph, Ar…) are new species of chemistry. The cycloaddition reaction of X2Si=Sn: is a new study field of stannylene chemistry. To explore the rules of cycloaddition reaction between X2Si=Sn: and the symmetric p-bonded compounds, the cycloaddition reactions of Cl2Si=Sn: and ethylene were selected as model reactions in this paper.The mechanism of cycloaddition reaction between singlet Cl2Si=Sn: and ethylene has been first investigated with the MP2/GENECP(C, H, Cl, Si in 6-311++G**;Sn in LanL2dz) method in this paper. From the potential energy profile, it could be predicted that the reaction has one dominant reaction channel. The reaction rule presented is that the 5p unoccupied orbital of Sn in Cl2Si=Sn: and the π orbital of ethylene forming a p→p donor-acceptor bond, resulting in the formation of an intermediate. Instability of the intermediate makes it isomerize to a four-membered Si-heterocyclic ring stannylene. Because the 5p unoccupied orbital of Sn atom in the four-membered Si-heterocyclic ring stannylene and the π orbital of ethylene form a p→p donor-acceptor bond, the four-membered Si-heterocyclic ring stannylene further combines with ethene to form another intermediate. Because the Sn atom in the intermediate shows sp3 hybridization after transition state, the intermediate isomerizes to a Si-heterocyclic spiro-Sn-heterocyclic ring compound. The research result indicates the laws of cycloaddition reaction between X2Si=Sn: and the symmetric π-bonded compounds. The study opens up a new research field for stannylene chemistry.展开更多
以工业水玻璃为硅源,采用溶胶-凝胶法制备了Si O2气凝胶;以Sn Cl2为Sn源,采用水热合成法制备了Si O2气凝胶/Sn复合负极材料。采用X射线衍射(XRD)、扫描电子显微镜(SEM)对材料的结构和形貌进行了表征,采用恒电流充放电测试了材料的电化...以工业水玻璃为硅源,采用溶胶-凝胶法制备了Si O2气凝胶;以Sn Cl2为Sn源,采用水热合成法制备了Si O2气凝胶/Sn复合负极材料。采用X射线衍射(XRD)、扫描电子显微镜(SEM)对材料的结构和形貌进行了表征,采用恒电流充放电测试了材料的电化学性能。结果表明Si O2气凝胶/Sn复合材料为三维多孔网络结构,金属Sn颗粒均匀地钉扎在Si O2气凝胶表面,该结构不仅可以改善颗粒的团聚性能,还可以大大缓解在充放电过程中的体积膨胀。电化学性能测试结果表明,在100 m A/g的电流密度下,复合材料首次可逆比容量可达472.93 m Ah/g,首次充放电效率86.19%。30次循环后可逆比容量仍可维持在417.70 m Ah/g,容量保持率76.13%,充放电效率接近100%,具有较好的电化学性能。展开更多
In the interlayer expansion of the layered zeolite precursor COK-5, a Sn, salt, bis（2,4-pentanedionate）- dichlorotin [Sn（acac）2CL2], instead of a silylating agent was used to link the layers at 180 ℃. The obtaine...In the interlayer expansion of the layered zeolite precursor COK-5, a Sn, salt, bis（2,4-pentanedionate）- dichlorotin [Sn（acac）2CL2], instead of a silylating agent was used to link the layers at 180 ℃. The obtained material, which is designed as Sn-COE-5, shows a shift of the first XRD reflection, which is very similar to that of COK-5 interlayer expanded with dichlorodimethylsilane （DCDMS）, indicating an increase in interlayer distance. X-ray diffraction （XRD）, N2 sorption isotherms, inductively coupled plasma （ICP）, and X-ray photo- electron spectroscopy （XPS） support the incorporation of isolated Sn sites in the sample. In the conversion of glucose to levulinic acid. Sn-COE-5 exhibits much higher activity than COK-5, which is due to the presence of Lewis acidic sites in the Sn-COE-5.展开更多
基金supported by the National Natural Science Foundation of China(No.51102114)
文摘X2Si=Sn:(X = H, Me, F, Cl, Br, Ph, Ar…) are new species of chemistry. The cycloaddition reaction of X2Si=Sn: is a new study field of stannylene chemistry. To explore the rules of cycloaddition reaction between X2Si=Sn: and the symmetric p-bonded compounds, the cycloaddition reactions of Cl2Si=Sn: and ethylene were selected as model reactions in this paper.The mechanism of cycloaddition reaction between singlet Cl2Si=Sn: and ethylene has been first investigated with the MP2/GENECP(C, H, Cl, Si in 6-311++G**;Sn in LanL2dz) method in this paper. From the potential energy profile, it could be predicted that the reaction has one dominant reaction channel. The reaction rule presented is that the 5p unoccupied orbital of Sn in Cl2Si=Sn: and the π orbital of ethylene forming a p→p donor-acceptor bond, resulting in the formation of an intermediate. Instability of the intermediate makes it isomerize to a four-membered Si-heterocyclic ring stannylene. Because the 5p unoccupied orbital of Sn atom in the four-membered Si-heterocyclic ring stannylene and the π orbital of ethylene form a p→p donor-acceptor bond, the four-membered Si-heterocyclic ring stannylene further combines with ethene to form another intermediate. Because the Sn atom in the intermediate shows sp3 hybridization after transition state, the intermediate isomerizes to a Si-heterocyclic spiro-Sn-heterocyclic ring compound. The research result indicates the laws of cycloaddition reaction between X2Si=Sn: and the symmetric π-bonded compounds. The study opens up a new research field for stannylene chemistry.
文摘以工业水玻璃为硅源,采用溶胶-凝胶法制备了Si O2气凝胶;以Sn Cl2为Sn源,采用水热合成法制备了Si O2气凝胶/Sn复合负极材料。采用X射线衍射(XRD)、扫描电子显微镜(SEM)对材料的结构和形貌进行了表征,采用恒电流充放电测试了材料的电化学性能。结果表明Si O2气凝胶/Sn复合材料为三维多孔网络结构,金属Sn颗粒均匀地钉扎在Si O2气凝胶表面,该结构不仅可以改善颗粒的团聚性能,还可以大大缓解在充放电过程中的体积膨胀。电化学性能测试结果表明,在100 m A/g的电流密度下,复合材料首次可逆比容量可达472.93 m Ah/g,首次充放电效率86.19%。30次循环后可逆比容量仍可维持在417.70 m Ah/g,容量保持率76.13%,充放电效率接近100%,具有较好的电化学性能。
基金supported by the National Natural Science Foundation of China (21422306 and 21403192)Zhejiang Provincial Natural Science Foundation of China under grant no. LR15B030001the Fundamental Research Funds for the Central Universities (2015XZZX004-04)
文摘In the interlayer expansion of the layered zeolite precursor COK-5, a Sn, salt, bis（2,4-pentanedionate）- dichlorotin [Sn（acac）2CL2], instead of a silylating agent was used to link the layers at 180 ℃. The obtained material, which is designed as Sn-COE-5, shows a shift of the first XRD reflection, which is very similar to that of COK-5 interlayer expanded with dichlorodimethylsilane （DCDMS）, indicating an increase in interlayer distance. X-ray diffraction （XRD）, N2 sorption isotherms, inductively coupled plasma （ICP）, and X-ray photo- electron spectroscopy （XPS） support the incorporation of isolated Sn sites in the sample. In the conversion of glucose to levulinic acid. Sn-COE-5 exhibits much higher activity than COK-5, which is due to the presence of Lewis acidic sites in the Sn-COE-5.
