Trisilylamine, , exhibits a completely planar geometry around the nitrogen atom, whereas trimethylam — Chemical Bonding Chemistry Question

💡 Solution & Explanation

In $N(SiH_3)_3$, the central nitrogen is $sp^2$ hybridized because its lone pair (in a $p$ -orbital) undergoes $p\pi-d\pi$ back bonding with the vacant $3d$ -orbitals of the adjacent silicon atoms. This delocalization flattens the molecule. Carbon in $N(CH_3)_3$ lacks vacant $d$ -orbitals, keeping N $sp^3$ hybridized (pyramidal).