Question

Which of the following statement is not correct about diborane?

• A. There are two 3-centre-2-electron bonds.
• B. The four terminal B-H bonds are two centre two electron bonds.
• C. The four terminal Hydrogen atoms and the two Boron atoms lie in one plane.
• D. Both the Boron atoms are sp₂ hybridised.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Diborane ($B_{2}H_{6}$) is an electron-deficient dimer of $BH_{3}$.
Its structure features unique banana bonds (bridge bonds).
Detailed Explanation:
Let's analyze the structural features:
(1) Statement (1): Diborane has two bridging $H$ atoms. The $B-H-B$ bonds involve three atoms but only two electrons.
This is correct.
(2) Statement (2): There are four terminal $B-H$ bonds which are standard $2c-2e$ covalent bonds.
This is correct.
(3) Statement (3): The four terminal hydrogens and the two boron atoms lie in a single plane.
The bridging hydrogens lie in a plane perpendicular to this.
This is correct.
(4) Statement (4): Each Boron atom in diborane is $sp^{3}$ hybridized.
Three orbitals contain an electron and one is empty to facilitate bridge bonding.
This statement is incorrect.
Step 2: Final Answer:
Statement (4) is the incorrect one. Boron is $sp^{3}$, not $sp^{2}$.