Question

The EAN of Co(CO)$_4$ is 35. It attains stability by

• A. Oxidation of [Co(CO)$_4$]
• B. Reduction of [Co(CO)$_4$]
• C. Dimerization of [Co(CO)$_4$]
• D. Both (B) and (C)

Hint:

Odd EAN complexes often stabilize via \textbf{electron pairing or dimer formation}.

Answer 1

The Correct Option is D

Step 1: A species with odd electron number (35) is unstable.
Step 2: Metal carbonyls stabilize by pairing electrons.
Step 3: Two possibilities: - Gain one electron → 36 e$^-$ (closed shell). - Combine two molecules → dimer with metal–metal bond.
Step 4: Therefore both reduction and dimerization stabilize. Hence → (D).