Sidgwick's EAN rule serves as an early model for predicting complex stability. Which of the followin — Coordination Compounds Chemistry Question
Question
Sidgwick's EAN rule serves as an early model for predicting complex stability. Which of the following observations concerning its applications and limitations is/are historically and conceptually accurate?
💡 Solution & Explanation
(A) True: The rule works best for carbonyls and low oxidation states, failing frequently elsewhere. (B) True: A metal-metal bond is shared, adding 1 electron to the count of each metal involved. (C) True: Fe(26) + 10 = 36. Mn(25) + 10 = 35. $Mn(CO)_5$ is unstable and typically dimerizes to $Mn_2(CO)_{10}$ to reach EAN=36. (D) False: Complexes with an EAN less than the noble gas configuration lack electrons, so they act as oxidizing agents (they undergo reduction by gaining electrons), not auto-reducing agents.