Ab Initio Study of Mechanism of Forming Spiro-Heterocyclic Ring Compound Involving Si and Ge from Dichlorosilylene Germylidene (Cl2Si=Ge:) and Acetone

摘要

The mechanism of the cycloaddition reaction between singlet state dichlorosilylene germylidene (Cl2Si=Ge:) and acetone has been investigated with B3LYP/6-31G and B3LYP/6-31G method, from the potential energy profile, we predict that the reaction has one dominant reaction pathway. The presented rule of the reaction is that the two reactants firstly form a Si-heterocyclic four-membcred ring gcrmylene through the [2+2] cycloaddition reaction. Because of the 4p unoccupied orbital of Ge atom in the Si-heterocyclic four-membered ring germylene and the n orbital of acetone forming a π → p donor-acceptor bond, the Si-heterocyclic four-membered ring germylene further combines with acetone to form an intermediate. Because the Ge atom in the intermediate hybridizes to an sp~3 hybrid orbital after the transition state, then, the intermediate isomerizes to spiro-heterocyclic ring compound involving Si and Ge (P4) via a transition state.