用高精度计算方法 CBS-4M,CBS-Q和CBS-QB3评估了26种单杂环分子的C-H键解离焓的实验值.结果表明,CBS-QB3方法最好,MD、MAD及RMSE分别为9.3、9.3和11.1 k J/mol.理论值与实验值的线性相关方程为y=0.928x+21.3,相关系数平方R2达0.980.通...用高精度计算方法 CBS-4M,CBS-Q和CBS-QB3评估了26种单杂环分子的C-H键解离焓的实验值.结果表明,CBS-QB3方法最好,MD、MAD及RMSE分别为9.3、9.3和11.1 k J/mol.理论值与实验值的线性相关方程为y=0.928x+21.3,相关系数平方R2达0.980.通过自然键轨道分析后发现,杂原子的电负性使得五元杂环的自然电荷分布发生变化.展开更多
Ten years after the first synthesis of neutral two-coordinated phosphorus in 1962, the first phosphenium cations were synthesized by Fleming, Lupton and Jekot in 1972. Up to now, though 30 years have passed, the membe...Ten years after the first synthesis of neutral two-coordinated phosphorus in 1962, the first phosphenium cations were synthesized by Fleming, Lupton and Jekot in 1972. Up to now, though 30 years have passed, the members of these phosphenium cations are still very few. the research of phosphenium cations is only limited in France, America and other countries. In our laboratory work was done on a new unique cation: the 5-methylthio-3-N-phenyl-2,3-2(H)-1,3,4,2-thiadiazaphosphenium cation which was found and characterized by 261.9 ppm conclusively of <sup>31</sup>p NMR. It also has an electric conductivity in nucleophilic and electrophilic reactions. We are interested in noticing that these phospbenium cations are stabilized by one sulfur atom besides nitrogen atoms.展开更多
文摘用高精度计算方法 CBS-4M,CBS-Q和CBS-QB3评估了26种单杂环分子的C-H键解离焓的实验值.结果表明,CBS-QB3方法最好,MD、MAD及RMSE分别为9.3、9.3和11.1 k J/mol.理论值与实验值的线性相关方程为y=0.928x+21.3,相关系数平方R2达0.980.通过自然键轨道分析后发现,杂原子的电负性使得五元杂环的自然电荷分布发生变化.
基金Project supported by the National Natural Fund for Young Scientists
文摘Ten years after the first synthesis of neutral two-coordinated phosphorus in 1962, the first phosphenium cations were synthesized by Fleming, Lupton and Jekot in 1972. Up to now, though 30 years have passed, the members of these phosphenium cations are still very few. the research of phosphenium cations is only limited in France, America and other countries. In our laboratory work was done on a new unique cation: the 5-methylthio-3-N-phenyl-2,3-2(H)-1,3,4,2-thiadiazaphosphenium cation which was found and characterized by 261.9 ppm conclusively of <sup>31</sup>p NMR. It also has an electric conductivity in nucleophilic and electrophilic reactions. We are interested in noticing that these phospbenium cations are stabilized by one sulfur atom besides nitrogen atoms.