Density functional theory study of mechanism of forming a spiro-Si-heterocyclic ring compound involving Ge from Cl 2 Ge=Si: And acetone

The mechanism of the cycloaddition reaction between singlet state Cl₂Ge=Si: And acetone has been investigated with density functional theory (DFT). From the potential energy profile, it can be predicted that the reaction has two competitive dominant reaction pathways. The presented rule of the reaction is that the [2+2] cycloaddition effect of the two p-bonds in Cl₂Ge=Si: And acetone leads to the formation of two four-membered Ge-heterocyclic ring silylenes (1. Ge and O in the opposite orientation; 2. Ge and O in the syn-position). Because of the 3p unoccupied orbital of the Si: Atom in two four-membered Ge-heterocyclic ring silylenes and the π orbital of acetone forming a π → p donor-acceptor bond, the two four-membered Ge-heterocyclic ring silylenes further combines with acetone to form an intermediate, respectively. Because the Si atom in two intermediates happens sp³ hybridization after transition state, then, two intermediates isomerizes to a spiro-Si-heterocyclic ring compound involving Ge via a transition state, respectively.