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In which of the following pairs, the two species are iso-structural?
A
$SO_3^{2-}$ and $NO_3^-$
B
$BF_3$ and $NF_3$
C
$BrO_3^-$ and $XeO_3$
D
$SF_4$ and $XeF_4$
Detailed Solution
$BrO_3^-$: total valence electrons $= 7 + 3 \times 6 + 1 = 26$. The central Br has 3 bond pairs and 1 lone pair, so it is $sp^3$ hybridised and the ion is trigonal pyramidal.
$XeO_3$: total valence electrons $= 8 + 3 \times 6 = 26$. The central Xe has 3 bond pairs and 1 lone pair, so it is $sp^3$ hybridised and the molecule is trigonal pyramidal.
Both have 26 valence electrons and in both cases the structure is trigonal pyramidal, so they are isostructural.
$SO_3^{2-}$ is pyramidal (one lone pair on S), but $NO_3^-$ is trigonal planar (no lone pair on N).
$BF_3$ is trigonal planar ($sp^2$), but $NF_3$ is pyramidal ($sp^3$ with one lone pair).
$SF_4$ is see-saw shaped ($sp^3d$ with one lone pair), but $XeF_4$ is square planar ($sp^3d^2$ with two lone pairs).
So the isostructural pair is $BrO_3^-$ and $XeO_3$.
$XeO_3$: total valence electrons $= 8 + 3 \times 6 = 26$. The central Xe has 3 bond pairs and 1 lone pair, so it is $sp^3$ hybridised and the molecule is trigonal pyramidal.
Both have 26 valence electrons and in both cases the structure is trigonal pyramidal, so they are isostructural.
$SO_3^{2-}$ is pyramidal (one lone pair on S), but $NO_3^-$ is trigonal planar (no lone pair on N).
$BF_3$ is trigonal planar ($sp^2$), but $NF_3$ is pyramidal ($sp^3$ with one lone pair).
$SF_4$ is see-saw shaped ($sp^3d$ with one lone pair), but $XeF_4$ is square planar ($sp^3d^2$ with two lone pairs).
So the isostructural pair is $BrO_3^-$ and $XeO_3$.