用从头算对丙烯和甲苯2个超共轭体系进行计算,结果表明甲基上氢原子参与超共轭时,其碳氢键键长增大,氢上集居数减少,丙烯、甲苯的甲基旋转势垒为7.61及0.096 kJ/mol.超共轭基作用相当于一带有孤对电子参与共轭之杂原子,超共轭体系不同...用从头算对丙烯和甲苯2个超共轭体系进行计算,结果表明甲基上氢原子参与超共轭时,其碳氢键键长增大,氢上集居数减少,丙烯、甲苯的甲基旋转势垒为7.61及0.096 kJ/mol.超共轭基作用相当于一带有孤对电子参与共轭之杂原子,超共轭体系不同构型稳定性可用M=sum from i=1 to 3(sinθ_i[sin(θ_i-α)+sinα])来表征。展开更多
Bonded tableau unitary group approach (BTUGA) is applied to the isoelec tronic series XO3 (X=B2-,C-, N and O+) and BF3 in the ab initio level. The relationship between structures and properties is analyzed. Results sh...Bonded tableau unitary group approach (BTUGA) is applied to the isoelec tronic series XO3 (X=B2-,C-, N and O+) and BF3 in the ab initio level. The relationship between structures and properties is analyzed. Results show that classical valence bond theory presented unsatisfactory descriptions on these systems and the diradical structures hold an important position in the groud state wavefunctions of the above systems. The structural weight of the diradical resonance structure in a system obviously correlates with the oxidizing power of the system.展开更多
文摘用从头算对丙烯和甲苯2个超共轭体系进行计算,结果表明甲基上氢原子参与超共轭时,其碳氢键键长增大,氢上集居数减少,丙烯、甲苯的甲基旋转势垒为7.61及0.096 kJ/mol.超共轭基作用相当于一带有孤对电子参与共轭之杂原子,超共轭体系不同构型稳定性可用M=sum from i=1 to 3(sinθ_i[sin(θ_i-α)+sinα])来表征。
文摘Bonded tableau unitary group approach (BTUGA) is applied to the isoelec tronic series XO3 (X=B2-,C-, N and O+) and BF3 in the ab initio level. The relationship between structures and properties is analyzed. Results show that classical valence bond theory presented unsatisfactory descriptions on these systems and the diradical structures hold an important position in the groud state wavefunctions of the above systems. The structural weight of the diradical resonance structure in a system obviously correlates with the oxidizing power of the system.
