Discuss the magnetic behaviour of [Fe(CN)6 ] 3– and [FeF6 ] 3–

Fe prefers to exist as Fe3+and is known to have acoordination numberof six. Since the configuration of Fe3+has five d electrons, we would expect to see five unpaired spins in complexes with Fe. This is true for [FeF6]3-; however,[Fe(CN)6]3-only has one unpaired electron, making it a weaker magnet. This trend can be explained based on the properties of the ligands. We expect CN−to have a stronger electric field than that of F−, so theenergylevel differences should be greater for the cyanide complex, resulting in something like this: .