Symmetry Selection Rules for Transition State Structures

2 Symmetry Selection Rules for Transition State Structures 

In those cases when the expected transition states of reactions may retain certain symmetry elements of the initial reactants and the products, invoking of the group-theoretical arguments may help formulate the rules of selection of the transition state structures by their symmetry [6, 48]. These rules, which are considered here in a simplified form, allow certain structures to be discarded straight away without checking them by calculating the matrices of force 

Stanton and Mclver [6] have formulated the following theorems intended to regulate the rules of selection of the energetically lowest transition states of reactions by the symmetry properties of the corresponding transition vectors  

1) The transition vector cannot belong to a degenerate representation of the point group of symmetry of the transition state. 

2) The transition vector is antisymmetrical with respect to those symmetry operations of the transition state which transform the reactants into the products. 

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