Structures and stabilities of 22 possible isomers for C78O2 based on C78（C2v） were studied by INDO series of methods. The most stable geometry is that two oxygen atoms are added to 1,2-bond crossed by the shortest z...Structures and stabilities of 22 possible isomers for C78O2 based on C78（C2v） were studied by INDO series of methods. The most stable geometry is that two oxygen atoms are added to 1,2-bond crossed by the shortest z axis and 32,35-bond near the longest x axis in C78（C2v）,in agreement with the experiment of adducts for C78（C2v）. 1,2,32,35-C78O2 is more stable than 1,2,19,22-C78O2 by 0.12 kcal/mol and epoxide structures are formed in each isomer. Electronic spectra for C78O2 were investigated with INDO/CIS method. The reason of the blue-shift for UV absorptions of 1,2,32,35-C78O2 compared with that of C78（C2v） was discussed and electronic transition was theoretically assigned.展开更多
The structures and spectra of 20 possible isomers of C78（CH2）3 have been studied by using AMI, INDO/CIS and DFT methods. The results show that the most stable isomer is 1,2,3,4,5,6-C78（CH2）3 （A） with annulene st...The structures and spectra of 20 possible isomers of C78（CH2）3 have been studied by using AMI, INDO/CIS and DFT methods. The results show that the most stable isomer is 1,2,3,4,5,6-C78（CH2）3 （A） with annulene structures, where three -CH2 groups are added to the 6/6 bonds located at the same hexagon passed by the shortest axis of C78 （C2v）. Compared with that of C78 （C2v）, the first absorption in the electronic spectrum of C78（CH2）3 （A） iS blue-shifted because of its wider LUMO-HOMO energy gap. While the IR frequencies of the C-C bonds on the carbon cage are red-shifted owing to the formation of annulene structures and the extension of the conjugated system. The chemical shifts of the carbon atoms in 13C NMR spectra are moved upfield upon the addition.展开更多
文摘Structures and stabilities of 22 possible isomers for C78O2 based on C78（C2v） were studied by INDO series of methods. The most stable geometry is that two oxygen atoms are added to 1,2-bond crossed by the shortest z axis and 32,35-bond near the longest x axis in C78（C2v）,in agreement with the experiment of adducts for C78（C2v）. 1,2,32,35-C78O2 is more stable than 1,2,19,22-C78O2 by 0.12 kcal/mol and epoxide structures are formed in each isomer. Electronic spectra for C78O2 were investigated with INDO/CIS method. The reason of the blue-shift for UV absorptions of 1,2,32,35-C78O2 compared with that of C78（C2v） was discussed and electronic transition was theoretically assigned.
文摘The structures and spectra of 20 possible isomers of C78（CH2）3 have been studied by using AMI, INDO/CIS and DFT methods. The results show that the most stable isomer is 1,2,3,4,5,6-C78（CH2）3 （A） with annulene structures, where three -CH2 groups are added to the 6/6 bonds located at the same hexagon passed by the shortest axis of C78 （C2v）. Compared with that of C78 （C2v）, the first absorption in the electronic spectrum of C78（CH2）3 （A） iS blue-shifted because of its wider LUMO-HOMO energy gap. While the IR frequencies of the C-C bonds on the carbon cage are red-shifted owing to the formation of annulene structures and the extension of the conjugated system. The chemical shifts of the carbon atoms in 13C NMR spectra are moved upfield upon the addition.
