By precisely mapping what happens when individual molecules collide, researchers have uncovered unanticipated details about the mechanism of the bimolecular nucleophilic substitution (SN2) reaction , a fundamental molecular transformation in organic synthesis (Science 2008, 319, 183).

In the classic SN2 mechanism, when a nucleophile such as a chloride anion attacks a compound such as methyl iodide, methyl iodide ejects the iodide "leaving group" and, like a cheap umbrella in high winds, undergoes an inversion of configuration to yield methyl chloride.

....click the link to read more