Ab initio study of mechanism of forming a spiro-heterocyclic ring compound with Si and Ge between dimethylsilylene germylidene (Me2Si = Ge:) and acetone

Abstract

The mechanism of the cycloaddition reaction between singlet state dimethylsilylene germylidene (Me(2)Si = Ge:) and acetone has been investigated with CCSD(T)//B3LYP/6-31G* method. From the potential energy profile, it could be predicted that the reaction has one dominant reaction pathway. The reaction rules presented are that the two reactants first 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 four-membered ring germylene and the π 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 happens sp(3) hybridization after transition state, then, the intermediate isomerizes to a spiro-heterocyclic ring compound with Si and Ge via a transition state.