JEE MainChemistryChemical Bonding and Molecular Structure
Which of the following complex ions does not exist?
Options
- A[ SiF ₆]²⁻
- B[ AlF ₆]³⁻
- C[ PF ₆]⁻
- D[ BF ₆]³⁻
Correct answer
D. [ BF ₆]³⁻
Step-by-step solution
Boron (B) belongs to the second period of the periodic table and has the valence shell electronic configuration 2s^2 2p^1 . Due to the absence of vacant d-orbitals in its valence shell, boron cannot expand its octet. Its maximum covalency is restricted to 4, forming species like [ BF ₄]^- . Silicon (Si), Aluminum (Al), and Phosphorus (P) belong to the third period and have vacant 3d-orbitals. This allows them to expand their octet and form hexa-coordinated species like [ SiF ₆]²⁻ , [ AlF ₆]³⁻ , and [ PF ₆]⁻ . There