Question #e9eb6

Sep 19, 2017

Diborane is nonpolar because it is a symmetrical molecule.

Explanation:

The structure of diborane is

Two of the $\text{H}$ atoms act as bridges between the $\text{B}$ atoms.

Theoretical calculations show that the partial charges on each atom are:

• $\text{B" color(white)(mmmmll)= "+2.12}$
• $\text{Bridging H" = color(white)(ll)"-0.71}$
• $\text{Terminal H" = color(white)(l) "-0.70}$

Thus, there are fairly large $\text{B-H}$ bond dipoles.

However, the diborane molecule is perfectly symmetrical.

Every $\text{B-H}$ bond dipole that points in one direction has a counterpart that points in exactly the opposite direction.

Thus, all bond dipoles cancel and diborane is a nonpolar molecule.