Stabilities and Electronic Spectra for C78O2 Isomers

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.