Oxidation state of Fe in Fe(CO)5 is zero. — Coordination Compounds Chemistry Question

💡 Solution & Explanation

Step 1: Recall the EAN formula: EAN = Z - (Oxidation State) + 2 * (Coordination Number). For pairs (a), (b), and (c), the metal, oxidation state, and coordination numbers are identical, so their EAN values are identical. Step 2: For option (d): In [Ni(CO)4], Ni is in the 0 oxidation state, so EAN = 28 - 0 + 2 * 4 = 36. In [Ni(CN)4]^2-, Ni is in the +2 oxidation state, so EAN = 28 - 2 + 2 * 4 = 34. Step 3: Since the EAN values of [Ni(CO)4] (36) and [Ni(CN)4]^2- (34) are different, option (d) is the pair with unequal EAN.