Which is not true about metal carbonyls? — Coordination Compounds Chemistry Question

💡 Solution & Explanation

Step 1: In metal carbonyls, synergic bonding involves the metal acting as a Lewis acid (by accepting a sigma pair from CO) and a Lewis base (by donating d-electrons). CO acts as a Lewis base (sigma donor) and a Lewis acid (accepting electrons into its empty antibonding pi* orbital). Step 2: The back-bonding involves the overlap of the filled d-orbitals of the transition metal (d_pi) with the empty pi* molecular orbitals of carbon (which have p-orbital character, p_pi). Step 3: Since the back-bonding is d_pi-p_pi (or d_pi-pi*) and not p_pi-p_pi, statement (d) is not true.