摘要
X2Si=Ge： （X = H, Me, F, CI, Br, Ph, Ar...） is a new species. Its cycloaddition reaction is a new area for the study of germylene chemistry. The mechanism of cycloaddition reaction between singlet state Me2Si=Ge： and formaldehyde has been investigated with the CCSD（T）//MP2/cc-pvtz method. From the potential energy profile, it could be predicted that the reaction has one dominant reaction pathway. The reaction rule presented is that the two reactants first form a four-membered Si-heterocyclic ring germylene through the [2＋2] cycloaddition reaction. Because of the 4p unoccupied orbital of Ge： atom in the four-membered Si-heterocyclic ring germylene and the π orbital of formaldehyde form a π→p donor-acceptor bond, the four-membered Si-heterocyclic ring germylene further combines with formaldehyde to form an intermediate. Because the Ge atom in the intermediate undergoes sp^3 hybridization after transition state, then the intermediate isomerizes to a spiro-Ge-heterocyclic ring compound involving Si via a transition state. The research result indicates the laws of cycloaddition reaction between HzSi=Ge： and formaldehyde. It has important reference value for the cycloaddition reaction between X2Si=Ge： （X = H, Me, F, CI, Br, Ph, Ar…） and asymmetric to-bonded compounds, which is significant for the synthesis of small-ring and spiro-Ge-heterocyclic compounds involving Si. The study extends research area and enriches the research content of germylene chemistry.
X2Si=Ge： （X = H, Me, F, CI, Br, Ph, Ar...） is a new species. Its cycloaddition reaction is a new area for the study of germylene chemistry. The mechanism of cycloaddition reaction between singlet state Me2Si=Ge： and formaldehyde has been investigated with the CCSD（T）//MP2/cc-pvtz method. From the potential energy profile, it could be predicted that the reaction has one dominant reaction pathway. The reaction rule presented is that the two reactants first form a four-membered Si-heterocyclic ring germylene through the [2＋2] cycloaddition reaction. Because of the 4p unoccupied orbital of Ge： atom in the four-membered Si-heterocyclic ring germylene and the π orbital of formaldehyde form a π→p donor-acceptor bond, the four-membered Si-heterocyclic ring germylene further combines with formaldehyde to form an intermediate. Because the Ge atom in the intermediate undergoes sp^3 hybridization after transition state, then the intermediate isomerizes to a spiro-Ge-heterocyclic ring compound involving Si via a transition state. The research result indicates the laws of cycloaddition reaction between HzSi=Ge： and formaldehyde. It has important reference value for the cycloaddition reaction between X2Si=Ge： （X = H, Me, F, CI, Br, Ph, Ar…） and asymmetric to-bonded compounds, which is significant for the synthesis of small-ring and spiro-Ge-heterocyclic compounds involving Si. The study extends research area and enriches the research content of germylene chemistry.
基金
supported by the National Natural Science Foundation of China(No.51102114)
