Theoretical Research On The Rule Of Cyclic Addition Of Silylene Germylene And Its Derivatives

We use the cycloaddition reactions between silylene germylene and its derivatives with ethylene, formaldehyde and acetone as the models to systematically study the mechanisms of these reactions, in order to explore the rules of the cycloaddition reactions between silylene germylene or its derivatives and the symmetry or asymmetry compounds.The principal means: MP2/6-31G* and B3LYP / 6-31G * implemented in Gaussian 98 package is made use of locating all the settled points along the reaction routes. All the parameters optimization on the reaction profile configurations. The energy of each configuration all undertakes zero point energy and CCSD (T) correction, the equilibrium configuration and the transient vibration analysis confirm its true and false. Through the intrinsic response coordinates (IRC) calculate and determine the transition state propertyThrough the rules of the cyclic additions between silylene germylene, dichloro-silylene germylidene, dimethyl-silylene germylidene and ethylene, we can predict that the cycloaddition reactions between them have the same mechanism, these reactions have only one dominant reaction pathway. it is that: the two reactants (R1, R2) firstly form a si-heterocyclic four-membered ring germylene, the Ge atom of which will be mixed of sp3, then it further reacts with ethylene (R2) to form a bis-heterocyclic compound with Si and Ge .According to the laws of the cyclic responses between silylene germylene, dichloro-silylene germylidene, dimethyl-silylene germylidene and formaldehyde, acetone, we predict that the cycloaddition reactions between them have the same mechanism, these reactions have only one dominant reaction pathway, it is that: the two reactants (R1, R2) firstly form a si-heterocyclic four-membered ring germylene through the [2+2] cycloaddition effect, the 4p unoccupied orbital of the Ge atom in which reacts with theÏ€- orbital of formaldehyde or acetone, forming aÏ€â†'p donor–acceptor bond. Then it further reacts with formaldehyde or acetone to form an intermediate, the Ge atom in which hybridizes to sp3 hybrid orbital after TS4, forming a bis-heterocyclic compound with Si and Ge.