An effective atomic number of Co(CO)4 is 35 and hence is less stable. It attains stability by : — Coordination Compounds Chemistry Question

💡 Solution & Explanation

Step 1: Co(CO)4 has an EAN of 35, which is one electron short of the stable noble gas configuration (Krypton, EAN = 36). Step 2: It can achieve an EAN of 36 either by gaining one electron via reduction to form [Co(CO)4]^- or by sharing an electron via dimerisation to form Co2(CO)8 with a Co-Co metal-metal bond. Step 3: Since both reduction and dimerisation allow the cobalt atom to attain a stable EAN of 36, the correct option is (d).