Computer Science & Engineering Quantum Chemistry LabList Of Experiments

Transition State Calculation for a SN2 reaction

When two (especially organic) molecules approach each other, there is a possibility of several different chemical reactions between them; each giving different products. Many reactions occur in a single step if the reactants collide with a suffucient energy and specific orientation to form a product. However, many reactions do not occur in a single step but follows multi-steps where it goes through many intermediate levels in a half-way and finally leads to product. These intermediate levels are known as transition states. Stabilisation of these transition states is very difficult because these are highly energetic and unstable species. A chemical reaction may go through many transition states and ultimately leads to the product.The number of transition states may be different for different reaction path ways for a chemical reaction. There are many different reaction path ways which leads to products from reactants example: Electrophilic reactions, Nucleophilic reactions etc

During these reactions already existing bonds will break and forms new bonds. SN2 is one of the mechanistic pathway where one nucleophile attacks the center of other molecule and forms the product. The elimination of leaving group and addition of attacking group takes place simultaneously.