Answer:
Boron and Aluminum
Explanation:
If you write the electron configuration for boron and aluminum, you get:
for boron and
for aluminum. Both have 3 valance electrons and has 2 electrons in a s-orbital and 1 in a p-orbital. These valance electron similarities are based on the column/group the elements are. Therefore, Boron and Aluminum have similar chemical behaviours and similar arrangement of outer/valance electrons.
This will give substituted product which will be by SN2 mechanism
so here we will get product with inverted geometry
In SN2 mechanism the nucleophile attacks from back side and we always get product with inverted geometry
This is known as Walden inversion.
Well, first we must remember that
This is because
So then