Paper: CSIR-NET June 2018 · Subject: Inorganic Chemistry · Chapter: Chemical Bonding · Topic: VSEPR Geometry · Marks: 2 · Difficulty: Medium
Dinuclear anion $\mathrm{[I_2(OH)_2O_8]^{4-}}$ has two bridging oxo groups. The geometry around each iodine is-
(a)Octahedral
(b)Monocapped octahedral
(c)Square pyramidal
(d)Pentagonal bipyramidal
Answer
Answer: A ✓ checked by 4AB · confidence medium
The source book printed no answer; this one was worked out and checked — see the explanation.
Explanation
[I₂(OH)₂O₈]⁴⁻ (H₂I₂O₁₀⁴⁻): oxidation state 2x + 2(−1) + 8(−2) = −4 ⇒ x = +7, so each I(VII) has no lone pair. The two bridging oxo groups are bonded to both iodines; the other 6 O and 2 OH are terminal, 4 per iodine. Each iodine therefore has 2 bridging + 4 terminal = 6 ligands (AX₆): two IO₆ octahedra sharing an edge. Geometry around each iodine: octahedral — option (a).