Theoretical study of mechanism of extraction reaction between silylene carbene and its derivatives and ethylene oxide

The mechanism of the oxide extraction reaction between singlet silylene carbene and its derivatives X₂Si = C: (X = H, F, Cl, CH₃)] and ethylene oxide has been investigated with density functional theory, including geometry optimization and vibrational analysis for the involved stationary points on the potential energy surface. The energies of the different conformations are calculated by B3LYP/6‐311G(d,p) method. From the potential energy profile, it can be predicted that the reaction pathway of this kind consists two steps, the first step is the two reactants firstly form an intermediate (INT) through a barrier‐free exothermic reaction; the second step is the INT then generates a product via a transition state (TS). This kind reaction has similar mechanism, when the silylene carbene and its derivatives X₂Si = C: (X = H, F, Cl, CH₃)] and ethylene oxide close to each other, the shift of 2p lone electron pair of O in ethylene oxide to the 2p unoccupied orbital of C in X₂Si = C: gives a p → p donor–acceptor bond, thereby leading to the formation of INT. As the p → p donor–acceptor bond continues to strengthen (that is, the C? O bond continues to shorten), the INT generates product (P + C₂H₄) via TS. It is the substituent electronegativity, which mainly affects the extraction reactions. When the substituent electronegativity is greater, the energy barrier is lower, and the reaction rate is greater. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011