Question:medium

Pick out the correct statement with respect to $[Mn(CN)_6]^{3-}$ :

Updated On: May 5, 2026
  • It is $sp^3d^2$ hybridised and tetrahedral
  • It is $d^2sp^3$ hybridised and octahedral
  • It is $dsp^2$ hybridised and square planar
  • It is $sp^3d^2$ hybridised and octahedral
Show Solution

The Correct Option is B

Solution and Explanation

The question asks about the hybridization and geometry of the complex ion \([Mn(CN)_6]^{3-}\). To determine the correct hybridization and geometry, follow these steps:

  1. Determine the oxidation state of the central metal atom:
    • Cyanide (\(CN^-\)) is a ligand with a charge of \(-1\).
    • Let the oxidation state of manganese (\(Mn\)) be \(x\).
    • The complex ion has a net charge of \(-3\), so: x + 6(-1) = -3
    • This simplifies to: x - 6 = -3
    • Therefore, x = +3.
  2. Write the electronic configuration of the central metal ion:
    • The electronic configuration of neutral Mn is \([Ar] 3d^5 4s^2\).
    • In the +3 oxidation state, Mn loses three electrons, giving \([Ar] 3d^4\).
  3. Determine the type of hybridization:
    • Cyanide (\(CN^-\)) is a strong field ligand that causes pairing of electrons in the 3d orbitals.
    • The electronic configuration after pairing becomes \([Ar] 3d^{3} 4s^0 4p^0 4d^0\).
    • To form an octahedral complex, six vacant hybrid orbitals are needed.
    • By using the 3d, 4s, and two 4p orbitals, the resulting hybridization is \(d^2sp^3\).
  4. Confirm the geometry:
    • With \(d^2sp^3\) hybridization, the geometry of the complex is octahedral.

Based on the above analysis, the correct statement is: "It is \(d^2sp^3\) hybridised and octahedral."

Explanation of other options:

  • \(sp^3d^2\) hybridized and tetrahedral: This is incorrect because tetrahedral complexes are generally not formed with this hybridization and number of ligands.
  • \(dsp^2\) hybridized and square planar: This is incorrect because square planar complexes typically involve \(d^8\) configurations, not \(d^4\).
  • \(sp^3d^2\) hybridized and octahedral: This is incorrect because this describes the geometrical configuration of complexes with empty d orbitals in the higher principal quantum number shell.
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