Question

Predict whether the following molecules are iso-structural or not. Justify your answer.
$\begin{array}{c}\left(i\right)NM{e}_3\\ \left(ii\right)N{\left(SiM{e}_3\right)}_3\end{array}$

Answer 1

$Nm{e}_3$ and $N\left(SiM{e}_3\right)$ are not isostructural.

$N(Me{)}_3$ is trigonal pyramidal while $N(SiM{e}_3{)}_3$ is trigonal planer due to back bonding in $N(SiM{e}_3{)}_3$ three $s{p}^2$ orbitals are used for bonding, giving a plane triangular structure. The line pairs of electrons occupy a $p-pi$. This overlaps with empty d-pi orbitals on each of the three silicon atoms and results in bonding.