Question

Identify the species which does **not** exist:

• A. \( [\text{SiF}_6]^{2-} \)
• B. \( [\text{SiCl}_6]^{2-} \)
• C. \( [\text{GeCl}_6]^{2-} \)
• D. \( [\text{Sn(OH)}_6]^{2-} \)

Hint:

Hexacoordination is feasible with small ligands (e.g., F⁻) or large central atoms. \( [\text{SiCl}_6]^{2-} \) is not stable due to steric repulsion.

Answer 1

The Correct Option is B

- \( [\text{SiF}_6]^{2-} \): Exists – small F⁻ can stabilize hexacoordination in silicon.
- \( [\text{SiCl}_6]^{2-} \): Does not exist – Cl⁻ is too large to allow 6 to coordinate around small Si atom due to steric hindrance.
- \( [\text{GeCl}_6]^{2-} \): Exists – germanium is larger than silicon, allows 6 Cl⁻ around it.
- \( [\text{Sn(OH)}_6]^{2-} \): Exists – tin can accommodate 6 OH⁻ ligands due to its larger size.