Why is the molecule nitrogen pentachloride impossible?

Answer 1

The small size of the central nitrogen means the larger chloride atoms cannot approach close enough to form stable N-Cl bonds due to mutual repulsive forces becoming dominant.

it is due to the absence of vacant dorbitals in N atom

Answer 2

The molecule nitrogen pentachloride (NCl5) is impossible because nitrogen does not have enough valence electrons to form five covalent bonds with chlorine atoms. Nitrogen typically forms a maximum of 3 covalent bonds due to its electron configuration, making the formation of NCl5 chemically unstable and energetically unfavorable.