Abstract: The structures of isomers and transition states of HBO2 system have been investigated using ab initio method at MP2/6311＋＋G(d,p) and QCISD(t)/6311＋＋G(3df,2p)//MP2/6311＋＋G(d,p) (singlepoint) levels of theory. The calculated results show that the chain like HOBO isomer(E1) is kinetically and thermodynamically the most stable isomer. The electronic structure of isomer E1 has been explored. Isomer E2 has C2v symmetry and HBO(O) structure is higher in energy than E1 by 381.72 kJ•mol－1. Because E2 is located in a deeper potential well, it is a stable isomer, and should be observed in experiments.

Key words: HBO₂ system, Electronic structure, Transition state, 　Stability, Isomerization