Mercurinium Ion Definition:

The intermediate formed during oxymercuration.

Mercurinium Ion Explained:

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.