Question

Postulate why the saturated molecule [FeCp(CO)3] forms easily from a solution of Fe(CO)s and NaCp in a 5000 torr nitrogen atmosphere, but does not react at all in a 5000 torr atmosphere of carbon monoxide.

Answer 1

The complex Fe(CO)₅ is a 18 electronic organometallic carbonyl which is stable in nature according to 18 electron rule so when it is converted into [FeCp(CO)₃] it is converted into a 19 electronic species which is unstable and shows a tendency towards oxidation. So when we try to do the reaction in N₂ atmosphere N₂ being non reactive in nature will not hinder the formation of the desired compound with the evolution of CO in the process. But if it is done in CO atmosphere according to La Chateleir's Principle the reaction will not be favored as the the reaction produces CO as a side product so in CO atmosphere the production of CO will be hindered and the reaction equilibrium will shift towards reactant side which has a more stable compound.