Theoretical Studies on the State Correlationandthe Mechanism of tne Unimolecular Dissociation of Methylformate Cation

Three reaction pathways of the unimolecular dissociation of methylformate radical cation

were studied by ab initio SCF MO method at the UHF/STO-3G level. The state correlation diagrams in Cs symmetry for reaction （1） and reaction （2） were examinated and some reaction pathways for ground and low-lying excited states were carried out based on the result of correlation diagrams. We investigated tne path of reaction （3） path in Cl symmetry. The transition states and the intermidiates for reaction （1） and reaction （3） were optimazed. Furthermore, the physical chemical variations along each reaction pathway were discussed. The activation barriers were corrected by using MCSCF method (193.24kJ∙mol^-1and 346.48 kJ∙ mol^-1 respectively for reaction （1） and reaction （3）).