Which species is isoelectronic with ${\mathrm{NO}}_2^{+}$ ?

The phrase "isoelectronic species," which means "same electric" or "equal charge," describes two atoms, ions, or molecules with the same electronic structure and the same amount of valence electrons.
No of $e^{-}$ in ${\mathrm{NO}}_2^{+}$ and  ${\mathrm{N}}_3^{-}$ are 44.