The bonding character of AISO isomers in quartet excited states:ab initio and density runctional theory studies

摘要

The geometries and the bonding properties have been predicted for four isomers of AISO species in the quartet state at density functional theory and coupled cluster[SSCD(T)]all-electron correlation levels with a large 6-311+G(3df)basis set Results have indicated that for the AISO species in quartet state the lowest state is ~4A" state which corresponds to a cyclic structure:the other three isomers (cyclic,bent and linear)are higher than the lowest state by 26.9kcal/mol(cyclic ~4A'),19.4kcal/mol(~4A"),and 28.3kcal/mol (linear AISO ~4sum),respectively.The calculated dissociatiion energies for the lowest quartet state species (AISO ~4A")are 27.3kcal/mol for the radical mechanism [M(~2P)+SO(~3sum~-)]and 154.7kcal/mol for the mechanism [M(~2P)+S(~3P)+O(~3P)].Inspectionof the bonding character indicates that the cyclic AISO species in the lowest quartet state (~4A") should be classified as thiodioxide(similar to disulfide or dioxide),and the cyclic ~4A' state should be classified as thiosuperoxide.The bent Al-SO(~4A")species has some thiosuperoxide character,while a weak interaction bonding.However,this thiosuperoxide is not as ionic as LiO_2 and LiSO and is also less ionic than the cyclic AlO_2.In addition,the combinations of Al with SO species exhibit the amphoteric character of Al.