Which of the following pairs of compounds is isoelectronic and isostructural?

- ${\text{IBr}}_2^{-}$: Valence electrons $=7(I)+2\times 7(Br)+1=22$. Structure: Linear ($s{p}^{3}d$, 3 lone pairs).${\text{XeF}}_2$: Valence electrons $=8(Xe)+2\times 7(F)=22$. Structure: Linear ($s{p}^{3}d$, 3 lone pairs).Since they have the same number of valence electrons and the same geometry, they are isoelectronic and isostructural.