The geometry and binding interaction of M+CO2 (M represents the firstrow transition metals) were studied using ab initio methods. In some cases the frequency calculations and basis set superposition error corrections ...The geometry and binding interaction of M+CO2 (M represents the firstrow transition metals) were studied using ab initio methods. In some cases the frequency calculations and basis set superposition error corrections were included. For all the complexes under the study, the linear structures were found to be the equilibrium structure. The distances of M+—O in R(M+—O) in which M has 4s electrons are obvious longer than those in which M has no 4s electrons, and from Sc to Zn the change trend is decreased, accompanied with some oscillation. The binding energy has an opposite change trend to that of the R(M+—O). Linear M+CO2 has the same spin as M+, while Tshape structures may have different spins. The static electronic interaction was found to be about 80% of the total binding energy.展开更多
The localized molecular orbitals and energy levels for four typical conjugated six-membered ring systems C_6H_6, C_3N_3H_3, B_3N_3H_6, and (B_3O_6)^(3-) as well as a non-aromatic reference molecule N_3Cl_6 have been ...The localized molecular orbitals and energy levels for four typical conjugated six-membered ring systems C_6H_6, C_3N_3H_3, B_3N_3H_6, and (B_3O_6)^(3-) as well as a non-aromatic reference molecule N_3Cl_6 have been calculated by using Edmiston-Ruedenberg energy localization technique under the CNDO/2 approximation in order to investigate the nature of aromaticity or quasi-aromaticity of the six-membered ring systems studied. The contour maps for π-type localized MO's (LMO) have been plotted to illustrate the bonding characteristics of the five ring systems studied. These LMO calculations show that for all the conjugated six-membered ring systems considered there exists local delocalization of π-bonds or three-centered and occasionally four-centered two-electron π-bonds in our terminology, and the cooperative effect among these π-bonds leading to the formation of a closed continuous x-conjugation system around the ring, which is necessary for the creation of aromaticity in the systems studied. We have been able to discuss the properties of these three-centered π-bonds in terms of the constituent atoms and electrons and the relevant orbitals involved.展开更多
The localized molecular orbitals (LMOs) of certain quasi-aromatic organic and inor- ganic molecules with six-membered rings have been calculated by virtue of the ab initio method using STO-3G and 4-31G basis sets as w...The localized molecular orbitals (LMOs) of certain quasi-aromatic organic and inor- ganic molecules with six-membered rings have been calculated by virtue of the ab initio method using STO-3G and 4-31G basis sets as well as the CNDO/2 method. It is shown that there exists extensively-delocalized p-pπ bonding in these quasi-aromatic systems. The localized pictures of the π-type LMOs for the heterocyclic and homocyclic systems from the σ-π localization scheme are discussed. The Generator Orbital approach is utilized to account for the bonding patterns.展开更多
文摘The geometry and binding interaction of M+CO2 (M represents the firstrow transition metals) were studied using ab initio methods. In some cases the frequency calculations and basis set superposition error corrections were included. For all the complexes under the study, the linear structures were found to be the equilibrium structure. The distances of M+—O in R(M+—O) in which M has 4s electrons are obvious longer than those in which M has no 4s electrons, and from Sc to Zn the change trend is decreased, accompanied with some oscillation. The binding energy has an opposite change trend to that of the R(M+—O). Linear M+CO2 has the same spin as M+, while Tshape structures may have different spins. The static electronic interaction was found to be about 80% of the total binding energy.
文摘The localized molecular orbitals and energy levels for four typical conjugated six-membered ring systems C_6H_6, C_3N_3H_3, B_3N_3H_6, and (B_3O_6)^(3-) as well as a non-aromatic reference molecule N_3Cl_6 have been calculated by using Edmiston-Ruedenberg energy localization technique under the CNDO/2 approximation in order to investigate the nature of aromaticity or quasi-aromaticity of the six-membered ring systems studied. The contour maps for π-type localized MO's (LMO) have been plotted to illustrate the bonding characteristics of the five ring systems studied. These LMO calculations show that for all the conjugated six-membered ring systems considered there exists local delocalization of π-bonds or three-centered and occasionally four-centered two-electron π-bonds in our terminology, and the cooperative effect among these π-bonds leading to the formation of a closed continuous x-conjugation system around the ring, which is necessary for the creation of aromaticity in the systems studied. We have been able to discuss the properties of these three-centered π-bonds in terms of the constituent atoms and electrons and the relevant orbitals involved.
基金Project supported by the National Natural Science Foundation of China the Foundation of the State Key Laboratory of Structural Chemistry of China
文摘The localized molecular orbitals (LMOs) of certain quasi-aromatic organic and inor- ganic molecules with six-membered rings have been calculated by virtue of the ab initio method using STO-3G and 4-31G basis sets as well as the CNDO/2 method. It is shown that there exists extensively-delocalized p-pπ bonding in these quasi-aromatic systems. The localized pictures of the π-type LMOs for the heterocyclic and homocyclic systems from the σ-π localization scheme are discussed. The Generator Orbital approach is utilized to account for the bonding patterns.
