Question

From the following : (A) $[\text{Co}(\text{NH}_3)_6]^{3+}$ : Inner orbital complex, $d^2sp^3$ hybridization (B) $[\text{MnCl}_4]^{2-}$ : Outer orbital complex, $sp^3d^2$ hybridization (C) $[\text{CoF}_6]^{3-}$ : Outer orbital complex, $d^2sp^3$ hybridization (D) $[\text{FeF}_6]^{3-}$ : Outer orbital complex, $sp^3d^2$ hybridization (E) $[\text{Ni}(\text{CN})_4]^{2-}$ : Inner orbital complex, $sp^3$ hybridization Choose the correct answer from the given options.

• A. A, B and C only
• B. C and E only
• C. A, B and D only
• D. C, D and E only

Hint:

Inner orbital complexes use $(n-1)d$ orbitals ($d^2sp^3$), while outer orbital complexes use $nd$ orbitals ($sp^3d^2$). Be careful with exceptions like tetrahedral complexes which are always high spin $sp^3$, unless otherwise noted.

Answer 1

The Correct Option is C

To determine the correctness of the given options based on the nature of the complexes and their hybridizations, we need to analyze each option individually: 

1. Complex: \([\text{Co}(\text{NH}_3)_6]^{3+}\)
   • The central metal ion is Co(III) with an electronic configuration: \([Ar] 3d^6\).
   • The ligand NH₃ is a strong field ligand, causing pairing of 3d electrons.
   • This results in the inner orbital complex with hybridization \(d^2sp^3\).
   • Conclusion: Option A is correctly identified as an inner orbital complex with \(d^2sp^3\) hybridization.
2. Complex: \([\text{MnCl}_4]^{2-}\)
   • The central metal ion is Mn(II), with an electronic configuration: \([Ar] 3d^5\).
   • Cl⁻ is a weak field ligand, which leads to no electron pairing and uses outer \(4d\) orbitals.
   • This results in an outer orbital complex with hybridization \(sp^3d^2\).
   • Conclusion: Option B is correctly identified as an outer orbital complex with \(sp^3d^2\) hybridization.
3. Complex: \([\text{CoF}_6]^{3-}\)
   • Co(III) has an electronic configuration: \([Ar] 3d^6\).
   • F⁻ is a weak field ligand, leading to the use of outer \(d\) orbitals.
   • This would ideally form an outer orbital complex with \(sp^3d^2\) hybridization, not \(d^2sp^3\) as stated.
   • Conclusion: Option C is incorrectly identified in terms of hybridization.
4. Complex: \([\text{FeF}_6]^{3-}\)
   • Fe(III) has an electronic configuration: \([Ar] 3d^5\).
   • F⁻ is a weak field ligand, using outer \(d\) orbitals.
   • This leads to an outer orbital complex with \(sp^3d^2\) hybridization.
   • Conclusion: Option D is correctly identified as an outer orbital complex with \(sp^3d^2\) hybridization.
5. Complex: \([\text{Ni}(\text{CN})_4]^{2-}\)
   • Ni(II) has an electronic configuration: \([Ar] 3d^8\).
   • CN⁻ is a strong field ligand, causing pairing of 3d electrons and utilizing inner d orbitals.
   • This results in an inner orbital complex with \(dsp^2\) hybridization instead of \(sp^3\).
   • Conclusion: Option E is incorrectly identified in terms of hybridization.

Based on the above analysis, the correct complexes are identified as A, B, and D only.