Complex ion [Co(NH3)6]2+ is readily oxidized to [Co(NH3)6]3+. — Coordination Compounds Chemistry Question

💡 Solution & Explanation

Step 1: In [Co(CO3)(NH3)5]ClO4, the cobalt center is bonded to five neutral NH3 ligands and one anionic, monodentate carbonate (CO3^2-) ligand, resulting in a coordination number of 6. Step 2: The complex cation is [Co(CO3)(NH3)5]^+ with a net charge of +1. The oxidation state of Co is calculated as: x - 2 + 5(0) = +1 => x = +3, which leaves 6 d-electrons (3d^6 configuration). Step 3: Because NH3 is a strong-field ligand, Co^3+ (3d^6) undergoes spin-pairing to form a low-spin octahedral complex with 0 unpaired electrons. Row (a) correctly lists these properties.