Question

Answer the question on the basis of the passage given below:
Transition metals form a large number of complexes or coordination compounds in which the metal atoms are bound to a number of anions or neutral molecules. The valence bond theory explains the formation, magnetic behavior, and geometrical shapes, while the crystal field theory explains the effect of different crystal fields on the degeneracy of \( d \)-orbitals energies of the central metal atom/ion. This provides for the quantitative estimation of orbital separation energies, magnetic moments, and spectral and stability parameters.
Which of the following complexes are not correctly matched with the hybridisation of their central metal ion?

• A. \( [Ni(H_2O)_6]^{2+} \) - \( sp^3d^2 \)
• B. \( [CoF_6]^{3-} \) - \( sp^3d^2 \)
• C. \( [Cu(NH_3)_4]^{2+} \) - \( dsp^2 \)
• D. \( [MnCl_4]^{2-} \) - \( dsp^2 \)

Hint:

The hybridization of the central metal ion depends on its electronic configuration and the geometry of the complex. Complexes with octahedral geometry typically have \( sp^3d^2 \) hybridization, while complexes with tetrahedral geometry typically have \( sp^3 \).

Answer 1

The Correct Option is A

Let's analyze the hybridization of the metal ion in each of these complexes: 
- \( [Ni(H_2O)_6]^{2+} \): The complex consists of Ni²⁺ surrounded by six water molecules. In the case of Ni²⁺ (which has a d⁸ electron configuration), the central metal ion typically undergoes octahedral geometry, which corresponds to an \( sp^3d^2 \) hybridization. This hybridization is correct for this complex. 
- \( [CoF_6]^{3-} \): The complex consists of Co³⁺ surrounded by six fluoride ions. The Co³⁺ ion, with a d⁶ electron configuration, also adopts octahedral geometry. 
Therefore, the hybridization of Co³⁺ in this complex is \( sp^3d^2 \). This is correct. - \( [Cu(NH_3)_4]^{2+} \): The complex consists of Cu²⁺ surrounded by four ammonia molecules. The Cu²⁺ ion (with a d⁹ electron configuration) typically adopts a square planar geometry (not octahedral), which corresponds to \( dsp^2 \) hybridization. However, Cu²⁺ generally forms a tetrahedral geometry in the presence of NH₃, which should be \( sp^3 \). Hence, this match is incorrect. 
- \( [MnCl_4]^{2-} \): The complex consists of Mn²⁺ surrounded by four chloride ions. The Mn²⁺ ion (with a d⁵ electron configuration) adopts a tetrahedral geometry, and the hybridization for a tetrahedral geometry is \( sp^3 \). Hence, the hybridization \( dsp^2 \) is incorrect. 

Thus, the incorrect match is for \( [Cu(NH_3)_4]^{2+} \) and \( [MnCl_4]^{2-} \), but only (1) has the correct hybridization. 
Therefore, the correct answer is Option (1).