Definition
The intermediate formed during oxymercuration.
Explanation
Since the initial alkene is achiral and the steric factors are the same for both approaches, we get both ions, which are enantiomers. Each enantiomer reacts stereo-specifically with water to produce a chiral product. Note that the position where the mercury sits is still a chirality center in this example, but in many simpler cases, it is not. Finally, NaBH4NaBHX4 is added to this compound as a second step to reduce the C−HgC−Hg bond to a C−HC−H bond. In most cases, if the mercury was at a chirality center, that position no longer is one because we have two C−HC−H bonds present.