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

Abstract

The mechanism of the cycloaddition reaction between singlet state dichlorosilylene germylidene (Cl 2 Si=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-membered ring germylene through the [2+2] cycloaddition reaction. Because of the 4p unoccupied orbital of Ge atom in the Si-heterocyclic fourmembered ring germylene and the π orbital of acetone forming a π → p donor-acceptor bond, the Siheterocyclic 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.