Question

How many structures are correct from below
(i) In diborane 12 valence $e^{-}$ are involved in bonding
(ii) In diborane, two boron and four terminal hydrogen, lie in the same plane.
(iii) Diborane has ethane-like structure
(iv) In diborane, bridging bonds are 3-centre 2- electron bond

• A. 3
• B. 3.0
• C. 3.00

Answer 1

Answer: (A), (B), (C)

Now, by looking at the structure of diborane, we can see that there are 12 valence electrons that are involved in bonding. 8 valence electrons are used in the four non-bridging hydrogen bonds and four valence electrons are shared in forming 3-centered 2-electron bonds. Therefore, statement 'a' and 'd' are correct.

(B). In diborane, maximum six atoms, two boron and four terminal hydrogen, lie in the same plane. By looking at the structure of diborane, we can see that two boron atoms and the four terminal hydrogen atoms of the molecule are in the same plane and the bridging hydrogen atoms lie above and below this plane. Therefore, statement (b) is also correct.

(C). Diborane has ethane-like structure: The structure of ethane has a single bond between the two carbon atoms but in diborane, there are bridged hydrogen-boron bonds. Therefore, it does not have an ethane-like structure. Hence, this is not correct.

Therefore, the correct statements are (i), (ii) and (iv).