Question

Specify the coordination geometry and hybridisation of $N$ and $B$ atoms in a $1:1$ complex of $B{F}_3$ and $N{H}_3$

• A. $N:$ tetrahedral, $s{p}^3;B:$ tetrahedral, $s{p}^3$
• B. $N:$ pyramidal, $s{p}^3;B:$ pyramidal, $s{p}^3$
• C. $N$ : pyramidal, $s{p}^3;B:$ planar, $s{p}^2$
• D. $N:$ pyramidal, $s{p}^3;B:$ tetrahedral $,s{p}^3$

Answer 1

Answer: (A)

$N{H}_3$ and $B{F}_3$ have $s{p}^3$ (pyramidal) and $s{p}^2$ (planar) hybridisation respectively having one lone pair of electron on $N$ atom which is responsible for pyramidal shape of $N{H}_3$ inspite of $s{p}^3$ hybridization. However, as soon as it is coordinated to $B{F}_3$, both attain tetrahedral geometry and acquire $s{p}^3$ hybridisation.