Among the following the pair in which the two species are not isostructural is:

Step-by-step solution

SiF ₄ and SF ₄ are not isostructural because SiF ₄ is tetrahedral due to s p^3 hybridisation while SF ₄ has distorted tetrahedral geometry due to presence of lone pair. Related Theory Two molecules are isostructural if they have a similar number of atoms arranged in a similar structure (spatial coordinates). Caution If they have same number of lone pair and bond pair, they are considered as isostructural.