<P> The reaction most often occurs at an aliphatic sp carbon center with an electronegative , stable leaving group attached to it ( often denoted X ) , which is frequently a halide atom . The breaking of the C -- X bond and the formation of the new bond ( often denoted C -- Y or C -- Nu ) occur simultaneously through a transition state in which a carbon under nucleophilic attack is pentacoordinate , and approximately sp hybridised . The nucleophile attacks the carbon at 180 ° to the leaving group , since this provides the best overlap between the nucleophile 's lone pair and the C -- X σ * antibonding orbital . The leaving group is then pushed off the opposite side and the product is formed with inversion of the tetrahedral geometry at the central atom . </P>
<P> The reaction most often occurs at an aliphatic sp carbon center with an electronegative , stable leaving group attached to it ( often denoted X ) , which is frequently a halide atom . The breaking of the C -- X bond and the formation of the new bond ( often denoted C -- Y or C -- Nu ) occur simultaneously through a transition state in which a carbon under nucleophilic attack is pentacoordinate , and approximately sp hybridised . The nucleophile attacks the carbon at 180 ° to the leaving group , since this provides the best overlap between the nucleophile 's lone pair and the C -- X σ * antibonding orbital . The leaving group is then pushed off the opposite side and the product is formed with inversion of the tetrahedral geometry at the central atom . </P>
where does the nucleophile attack in an sn2 mechanism
where does the nucleophile attack in an sn2 mechanism
at 180 ° to the leaving group
at 180 ° to the leaving group