Abstract: Using B3LYP functional with 6-311+G** basis set, the structures, stabilities and vibrational frequencies of a kind of novel diboron organic compound C9B2H6 containing a planar tetracoordinated carbon (ptC)were investigated. The results showed that there was a significant relationship between the stability and the positions of the two boron atoms, and boron atoms played a σ-donating and π-accepting role. The most stable structure was isomer (1,5) with C2v symmetry, in which the two boron atoms connected with the ptC atom and located on a same six-membered ring. Analysis of occupied πorbitals of isomer (1,5) indicated that it satisfied 4n+2 rule (10π electrons). And the calculated NICS (nucleus-independent chemical shift) values of isomer (1,5) showed that the high aromaticity located at the two three-membered rings, rather than the six-membered rings.

Key words: Hybrid density functional, Planar tetracoordinated carbon, Diboron organic compound, Aromaticity