Question

Which of the following species is not stable ?

• A. \([SiF_6]^{2-}\)
• B. \([GeCl_6]^{2-}\)
• C. \(Sn(OH)_6]^{2-}\)
• D. \([SiCl_6]^{2-}\)

Answer 1

The Correct Option is D

To determine which of the given chemical species is not stable, we need to consider the stability of these species based on their chemical properties and bonding structures.

1. \([SiF_6]^{2-}\): Silicon hexafluoride is a stable compound. Silicon can form a stable hexafluoride complex because fluoride ions are small and can effectively stabilize the negative charge on the silicon.
2. \([GeCl_6]^{2-}\): Germanium hexachloride is also stable. Germanium, like silicon, can also maintain a stable octahedral structure with chlorine ligands, although chlorides are larger compared to fluorides.
3. \([Sn(OH)_6]^{2-}\): Tin hydroxide complex is stable in such a configuration. Tin, being a group 14 element, can coordinate with the hydroxide ions forming a stable structure.
4. \([SiCl_6]^{2-}\): This is the species that is not stable. Silicon, unlike more extensive atoms such as germanium or tin, cannot effectively form a stable octahedral structure with larger chloride ions due to size limitations and electronic factors.

Based on the above reasoning, the instability of \([SiCl_6]^{2-}\) arises due to silicon's inability to accommodate six large chloride ions effectively, leading to insufficient shielding of the anionic charge and making the complex unstable.