The potential energy surfaces （PES） of unimolecular dissociation reactions for di-ethyl beryl- lium and di-t-butyl beryllium are investigated by B3LYP, CCSD（T）, and G3B3 approaches. Possible reaction pathways thro...The potential energy surfaces （PES） of unimolecular dissociation reactions for di-ethyl beryl- lium and di-t-butyl beryllium are investigated by B3LYP, CCSD（T）, and G3B3 approaches. Possible reaction pathways through either the radical or transition state （TS） of the molecules are considered. The geometries, vibrational frequencies and relative energies for various sta- tionary points are determined. From the study of energetics, the TS pathways arising from concerted molecular eliminations are indicated to be the main dissociation pathways for both molecules. The PES differences of the dissociation reactions are investigated. The activation energies and rate constants will be helpful for investigating the predictive ability of the reaction in further theoretical and experimental research.展开更多
A series of nickel halides bearing 2,4-di-t-butyl-6-（quinolin-8-yliminomethyl） phenolate ligands was synthesized and characterized by IR spectroscopy and elemental analysis. Molecular structures of C1 （R = H, X = B...A series of nickel halides bearing 2,4-di-t-butyl-6-（quinolin-8-yliminomethyl） phenolate ligands was synthesized and characterized by IR spectroscopy and elemental analysis. Molecular structures of C1 （R = H, X = Br） and C2 （R = H, X = C1） were further confirmed by single-crystal X-ray crystallographic studies, and revealed a distorted square planar geometry at nickel. Upon activation with diethylaluminum chloride （Et2AlCl）, all nickel pre-catalysts displayed good catalytic activity [up to 9.3 × 10^5 g mol-1（Ni） h-1] for ethylene oligomerization with major dimerization. In the presence of methylaluminoxane （MAO）, the nickel complex C1 was capable of ethylene polymerization under 3 MPa, and produced polyethylene products with narrow polydispersity （1.16-1.73） and molecular weights in the range of 2.6-4.95 kg/mol.展开更多
以三(3,5-二叔丁基水杨醛缩苯乙胺)镧La(OPEBS)3为引发剂引发L-丙交酯(L-LA)和ε-己内酯(ε-CL)的共聚,可控合成嵌段共聚物.研究了单体加料顺序、投料比、单体与引发剂的摩尔比(M/I)及聚合温度对L-LA和ε-CL共聚的影响.由石油醚抽提纯...以三(3,5-二叔丁基水杨醛缩苯乙胺)镧La(OPEBS)3为引发剂引发L-丙交酯(L-LA)和ε-己内酯(ε-CL)的共聚,可控合成嵌段共聚物.研究了单体加料顺序、投料比、单体与引发剂的摩尔比(M/I)及聚合温度对L-LA和ε-CL共聚的影响.由石油醚抽提纯化的聚合物经GPC、1 H NMR和DSC分析,表明该共聚物为L-LA和ε-CL嵌段共聚物.展开更多
基金ACKNOWLEDGMENTS This work was supported by the NationM Nature Science Foundation of China （No.11104256） and the Open Project of State Key Laboratory Cultivation base for Nonmetal Composites and Functional Mate- rials （No.11zxfk19）. We thank Dr. Shuang-lin Hu from the Chemistry Department of Uppsala University in Sweden for helpful suggestion. We would also thank the Hefei National Laboratory for Physical Sciences at the Microscale in University of Science and Technology of China for the computational facilities （Gaussian 09）.
文摘The potential energy surfaces （PES） of unimolecular dissociation reactions for di-ethyl beryl- lium and di-t-butyl beryllium are investigated by B3LYP, CCSD（T）, and G3B3 approaches. Possible reaction pathways through either the radical or transition state （TS） of the molecules are considered. The geometries, vibrational frequencies and relative energies for various sta- tionary points are determined. From the study of energetics, the TS pathways arising from concerted molecular eliminations are indicated to be the main dissociation pathways for both molecules. The PES differences of the dissociation reactions are investigated. The activation energies and rate constants will be helpful for investigating the predictive ability of the reaction in further theoretical and experimental research.
文摘A series of nickel halides bearing 2,4-di-t-butyl-6-（quinolin-8-yliminomethyl） phenolate ligands was synthesized and characterized by IR spectroscopy and elemental analysis. Molecular structures of C1 （R = H, X = Br） and C2 （R = H, X = C1） were further confirmed by single-crystal X-ray crystallographic studies, and revealed a distorted square planar geometry at nickel. Upon activation with diethylaluminum chloride （Et2AlCl）, all nickel pre-catalysts displayed good catalytic activity [up to 9.3 × 10^5 g mol-1（Ni） h-1] for ethylene oligomerization with major dimerization. In the presence of methylaluminoxane （MAO）, the nickel complex C1 was capable of ethylene polymerization under 3 MPa, and produced polyethylene products with narrow polydispersity （1.16-1.73） and molecular weights in the range of 2.6-4.95 kg/mol.
文摘以三(3,5-二叔丁基水杨醛缩苯乙胺)镧La(OPEBS)3为引发剂引发L-丙交酯(L-LA)和ε-己内酯(ε-CL)的共聚,可控合成嵌段共聚物.研究了单体加料顺序、投料比、单体与引发剂的摩尔比(M/I)及聚合温度对L-LA和ε-CL共聚的影响.由石油醚抽提纯化的聚合物经GPC、1 H NMR和DSC分析,表明该共聚物为L-LA和ε-CL嵌段共聚物.
