Question

Select correct statement about $B_2{H}_6$ :

• A. bridging groups are electron deficient with 12 valence electrons
• B. it has $2c-2e$ $B-H$ bonds
• C. it has $3c-2e$ $B-H$ bonds
• D. all of above are correct statements

Answer 1

Answer: (B), (C)

The correct options are
B it has $2c-2e$ $B-H$ bonds
C it has $3c-2e$ $B-H$ bonds

Diborane is an electron deficient compound. In diborane, total number of valence electrons is 12. diborane contains two coplanar $B{H}_2$ groups. Diborane has four terminal hydrogen atoms and the two boron atoms lie in one plane. Above and below this plane, there are two bridge hydrogen atoms. The bridge hydrogen atoms are present in a plane perpendicular to rest of the molecule. Each bridge hydrogen is bonded to the two boron atoms only by sharing of two electrons. These are called three centred two electron ($3c-2e$) bonds, also known as banana or tau bonds. The terminal $B-H$ bonds are $2c-2e$ bonds.