Question

Most stable nitrogen halide is:

• A. $N{I}_3$
• B. $NB{r}_3$
• C. $NC{l}_3$
• D. $N{F}_3$

Answer 1

The correct option is D $N{F}_3$

$N{F}_3$ is more stable than the other $N{X}_3$ because of the very low F-F bond energy (159 kJ $mo{l}^{-1}$). This has been ascribed to repulsions
between lone pairs on the two rather proximate fluorine atoms. Additionally, the N-F bond is also particularly strong, as would be expected for a linkage
between two elements in the first short period. The other $N{X}_3$ molecules may be less stable than $N{F}_3$ owing to congestion round the small
central nitrogen atom leading to non-bonded repulsive interactions between the halogens. This is particularly bad for large iodine atoms.