Paper: CSIR-NET June 2014 · Subject: Inorganic Chemistry · Chapter: Chemical Bonding · Topic: Chemical Bonding – General · Marks: 2 · Difficulty: Easy
The correct non-linear and iso-structural pair is
(a)$\mathrm{SCl_2}$ and $\mathrm{I_3^{-}}$
(b)$\mathrm{SCl_2}$, and $\mathrm{I_3^{+}}$
(c)$\mathrm{SCl_2}$, and $\mathrm{ClF_2^{-}}$
(d)$\mathrm{I_3^{+}}$ and $\mathrm{ClF_2^{-}}$
Answer
Answer: B ✓ checked by 4AB · confidence high
I₃⁻ and ClF₂⁻ (both AX₂E₃) are linear; only SCl₂ and I₃⁺ (both AX₂E₂) are bent.
Explanation
Count the electron pairs on the central atom. SCl₂: S has 2 bond pairs + 2 lone pairs (AX₂E₂) → bent. I₃⁺: the central I⁺ has 6 valence electrons → 2 bond pairs + 2 lone pairs (AX₂E₂) → bent. I₃⁻: the central I has 2 bond pairs + 3 lone pairs (AX₂E₃) → linear. ClF₂⁻: Cl has 2 bond pairs + 3 lone pairs (AX₂E₃) → linear. Pairs (a), (c) and (d) each contain a linear species, so the only non-linear, iso-structural pair is SCl₂ and I₃⁺ — option (b).