The species which has four unpaired electron is : — Coordination Compounds Chemistry Question

💡 Solution & Explanation

Step 1: Identify the oxidation state and configuration of the central metal in each complex ion: (a) Co^2+ is 3d^7, (b) Cr^3+ is 3d^3, (c) Fe^2+ is 3d^6, (d) Fe^3+ is 3d^5. Step 2: In [FeCl4]^2-, the central Fe^2+ (3d^6) ion is in a tetrahedral crystal field with weak-field Cl^- ligands, giving an e^3 t_2^3 configuration. Step 3: This configuration results in exactly 4 unpaired electrons. Thus, [FeCl4]^2- is the correct choice.