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Difficulty: Very hardTransition Metals: General Properties, Catalytic Behavior, and Complex Ions

Match each transition metal complex ion on the left with its corresponding structural, electronic, and magnetic characteristics on the right.

  • [Fe(CN)6]3−[Fe(CN)_6]^{3-}Octahedral geometry with a 3d53d^5 low-spin central metal ion containing 1 unpaired electron
  • [Ni(CN)4]2−[Ni(CN)_4]^{2-}Square planar geometry with a 3d83d^8 central metal ion that is diamagnetic
  • [Co(NH3)6]3+[Co(NH_3)_6]^{3+}Octahedral geometry with a 3d63d^6 low-spin central metal ion that is diamagnetic
  • [Cu(NH3)4]2+[Cu(NH_3)_4]^{2+}Square planar geometry with a 3d93d^9 central metal ion containing 1 unpaired electron

Answer

[Fe(CN)6]3−[Fe(CN)_6]^{3-} matches Octahedral geometry with a 3d53d^5 low-spin central metal ion containing 1 unpaired electron; [Ni(CN)4]2−[Ni(CN)_4]^{2-} matches Square planar geometry with a 3d83d^8 central metal ion that is diamagnetic; [Co(NH3)6]3+[Co(NH_3)_6]^{3+} matches Octahedral geometry with a 3d63d^6 low-spin central metal ion that is diamagnetic; [Cu(NH3)4]2+[Cu(NH_3)_4]^{2+} matches Square planar geometry with a 3d93d^9 central metal ion containing 1 unpaired electron.
Each complex ion's central metal ion exhibits a specific oxidation state, electronic configuration, coordination geometry, and spin state based on crystal field theory and ligand field strength. [Fe(CN)6]3−[Fe(CN)_6]^{3-} features Fe3+Fe^{3+} (3d53d^5) in a low-spin octahedral state with 1 unpaired electron. [Ni(CN)4]2−[Ni(CN)_4]^{2-} features Ni2+Ni^{2+} (3d83d^8) in a square planar diamagnetic configuration. [Co(NH3)6]3+[Co(NH_3)_6]^{3+} features Co3+Co^{3+} (3d63d^6) in a low-spin octahedral diamagnetic state. [Cu(NH3)4]2+[Cu(NH_3)_4]^{2+} features Cu2+Cu^{2+} (3d93d^9) in a square planar configuration with 1 unpaired electron.

Step-by-Step Solution

1
Determine the oxidation state and d-electron count of the central metal ion in each complex ion.
For [Fe(CN)6]3−[Fe(CN)_6]^{3-}, Fe3+Fe^{3+} is 3d53d^5. For [Ni(CN)4]2−[Ni(CN)_4]^{2-}, Ni2+Ni^{2+} is 3d83d^8. For [Co(NH3)6]3+[Co(NH_3)_6]^{3+}, Co3+Co^{3+} is 3d63d^6. For [Cu(NH3)4]2+[Cu(NH_3)_4]^{2+}, Cu2+Cu^{2+} is 3d93d^9.
Ligand charges (CN−CN^- = −1-1, NH3NH_3 = 00) determine the oxidation state of the central transition metal ion.
2
Analyze ligand strength, coordination geometry, and crystal field splitting to determine magnetic character.
[Fe(CN)6]3−[Fe(CN)_6]^{3-} is octahedral low-spin (t2g5t_{2g}^5, 1 unpaired e−e^-). [Ni(CN)4]2−[Ni(CN)_4]^{2-} is square planar (dsp2dsp^2, diamagnetic). [Co(NH3)6]3+[Co(NH_3)_6]^{3+} is octahedral low-spin (t2g6t_{2g}^6, diamagnetic). [Cu(NH3)4]2+[Cu(NH_3)_4]^{2+} is square planar (3d93d^9, 1 unpaired e−e^-).
Strong-field ligands (CN−CN^-, NH3NH_3) induce electron pairing in low-spin octahedral or square planar configurations.
3
Match each complex ion to its complete set of physical, electronic, and magnetic properties.
Each complex correctly aligns with its unique d-electron configuration, geometry, and spin state.
Verifies all coordination parameters systematically.

Key Concept

Electronic Configuration, Oxidation State, Geometry, and Magnetic Properties of Transition Metal Complexes
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Topics

Transition Metals: General Properties, Catalytic Behavior, and Complex Ions

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