Features of Mechanism of Cycloaddition Reaction between H2Sn=Sn: and Ethylene

Abstract

X 2 Sn=Sn: (X = H, Me, F, Cl, Br, Ph, Ar, …) are new species of chemistry. The cycloaddition reaction of X 2 Sn=Sn: are new study field of stannylene chemistry. To explore the rules of cycloaddition reaction between X 2 Sn=Sn: and the symmetric π-bonded compounds, the cycloaddition reactions of H 2 Sn=Sn: and ethylene were selected as model reactions in this paper. The mechanism of cycloaddition reaction between singlet H 2 Sn=Sn: and ethylene has been first investigated with the MP2/GENECP (C, H in 6-311++G**; Sn in LanL2dz) method in this paper. From the potential energy profile, it could be predicted that the reaction has one dominant reaction channel. The reaction rule presented is that the two reactants firstly form a four-membered Sn-heterocyclic ring stannylene through the [2 + 2] cycloaddition reaction. Because of the 5p unoccupied orbital of Sn: atom in the four-membered Sn-heterocyclic ring stannylene and the π orbital of ethylene forming a π → p donor-acceptor bond, the four-membered Sn-heterocyclic ring stannylene further combines with ethylene to form an intermediate. Because the Sn: atom in intermediate happens sp 3 hybridization after transition state, then, intermediate isomerizes to a spiro-Sn-heterocyclic ring compound. The research result indicates the laws of cycloaddition reaction between X 2 Sn=Sn: and the symmetric π-bonded compounds. The study opens up a new research field for stannylene chemistry.