A list of species having the formula $\mathrm{XZ}_{4}$ is given below. $\mathrm{XeF}_{4}, \mathrm{SF}_{4}, \mathrm{SiF}_{4}, \mathrm{BF}_{4}{ }^{-}, \mathrm{BrF}_{4}{ }^{-},\left[\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4}\right]^{2+},\left[\mathrm{FeCl}_{4}\right]^{2-},\left[\mathrm{CoCl}_{4}\right]^{2-}$ and $\left[\mathrm{PtCl}_{4}\right]^{2-}$. Defining shape on the basis of the location of X and Z atoms, the total number of species having a square planar shape is

Chemical Bonding and Molecular Structure — JEE Advanced · 2014 · 25 May 2014 · Paper 1 Question with Solution

A list of species having the formula

XZ_{4}

is given below.

XeF_{4}, SF_{4}, SiF_{4}, BF_{4}^{-}, BrF_{4}^{-}, [Cu (NH_{3})_{4}]^{2 +}, [FeCl_{4}]^{2 -}, [CoCl_{4}]^{2 -}

and

[PtCl_{4}]^{2 -}

.
Defining shape on the basis of the location of X and Z atoms, the total number of species having a square planar shape is

Answer: 4

Square planar geometry requires the central atom and four ligands to lie in the same plane. Analyzing each species:

$XeF_{4}$ : Xe has 8 valence electrons, 4 bond pairs, 2 lone pairs → square planar. ✓
$SF_{4}$ : S has 6 valence electrons, 4 bond pairs, 1 lone pair → see-saw shape. ✗
$SiF_{4}$ : Si has 4 valence electrons, 4 bond pairs, 0 lone pairs → tetrahedral. ✗
$BF_{4}^{-}$ : B has 4 valence electrons (with the extra electron), 4 bond pairs → tetrahedral. ✗
$BrF_{4}^{-}$ : Br has 8 valence electrons, 4 bond pairs, 2 lone pairs → square planar. ✓
$[Cu (NH_{3})_{4}]^{2 +}$ : Cu²⁺ (d⁹) in strong field → square planar. ✓
$[FeCl_{4}]^{2 -}$ : Fe²⁺ (d⁶) with weak field Cl⁻ → tetrahedral. ✗
$[CoCl_{4}]^{2 -}$ : Co²⁺ (d⁷) with weak field Cl⁻ → tetrahedral. ✗
$[PtCl_{4}]^{2 -}$ : Pt²⁺ (d⁸) in strong field → square planar. ✓

Total square planar species: 4 (

XeF_{4}

BrF_{4}^{-}

[Cu (NH_{3})_{4}]^{2 +}

[PtCl_{4}]^{2 -}

)

JEE Advanced · 2014 · 25 May 2014 · Paper 1 · Integer answer