Question

In which of the following compounds, observed bond angle is found to be greater than expected, but not due to back bonding.

• A. $N(Si{H}_3{)}_3$
• B. $N(C{H}_3{)}_3$
• C. $O(C{H}_3{)}_2$
• D. $O(Si{H}_3{)}_2$

Answer 1

Answer: (B), (C)

$O(C{H}_3{)}_2$

Due to $2P_{\pi }-3d_{\pi }$ back bonding, observed bond angle in $N(Si{H}_3{)}_3$ and $O(Si{H}_3{)}_2$ is higher than expected.


both $N(C{H}_3{)}_3$ and $O(C{H}_3{)}_2$ have no back bonding but higher bond angle is due to steric repulsions between the methyl groups.