Question

${\mathrm{SbF}}_5$ reacts with ${\mathrm{XeF}}_4$ to form an adduct. The shapes of cation and anion in the adduct are respectively:

• A. Square planar, trigonal bipyramidal
• B. Square planar, octahedral
• C. T-shaped, octahedral
• D. Square pyramidal, octahedral

Answer 1

The correct option is C

T-shaped, octahedral

Explanation:

Option C

Adduct:

• An adduct is a product of the direct addition of two or more distinct molecules, resulting in a single reaction product containing all the atoms of all components.
• ${\mathrm{XeF}}_4$ or xenon tetrafluoride reacts with ${\mathrm{SbF}}_5$ or antimony pentafluoride which is Lewis acid and forms an adduct.

Chemical reaction:

${\mathrm{XeF}}_4\left(\mathrm{aq}\right)+{\mathrm{SbF}}_5\left(\mathrm{aq}\right)\to {\left[{\mathrm{XeF}}_3\right]}^{+}{\left[{\mathrm{SbF}}_6\right]}^{-}\left(\mathrm{aq}\right)$

In the ${\mathrm{XeF}}^{3+}$cation:

• The total number of valence electron pairs on Xe=5.
• Number of lone pairs on Xe=2
• Number of sigma bonds =3
• Hybridization = sp³d
• The shape of the molecule with sp³d hybridization and two lone pairs is bent T−shaped.

In the ${{\mathrm{SbF}}^{-}}_6$anion:

• The total number of the valence electrons in Sb = 5.
• Hybridization = sp³d².
• The shape of the molecule with sp³d² hybridization is octahedral.

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Thus, the cation is T-shaped and the anion is octahedral.

Therefore, option C is correct.