In which of the following pairs, the two species are not isostructural?

Options

A. `PCl_4^(+) and SICl_4`
B. `PF_5 and BrF_5`
C. `AIF_6^(3+) and SF_6`
D. `CO_3^(2-) and NO_3^(-)`

Answer

B

Explanation

`PF_5 (sp^3d)` has trigonal bipyramidal geometry while `BrF_5 (ds^3 d^2)` has square bipyramidal or distorted octahedral geometry. All the remaining have same structure.
`PCl_4^(-) and SiCl_4` (tetrahedral -`sp^3`). `AIF_6^(3+)` and `SF_6` (octahedral-`sp^3 d^2`): and `CO_3^(2-)` and `NO_3^-` (trigonal -`sp^2`)