How does the magnetic data for coordination compounds with d⁴ and d⁵ ions present a complication, as seen in [Mn(CN)₆]³⁻ and [Fe(CN)₆]³⁻?

The magnetic data for coordination compounds with d⁴ and d⁵ ions, exemplified by [Mn(CN)₆]³⁻ and [Fe(CN)₆]³⁻, pose a complication. While [Mn(CN)₆]³⁻ has a magnetic moment suggesting two unpaired electrons, [Fe(CN)₆]³⁻ exhibits a paramagnetic moment indicating five unpaired electrons. According to conventional expectations, the d⁴ configuration should have one unpaired electron, and d⁵ should have two. However, ligand field theory explains this anomaly by considering the inner orbital hybridization. Both complexes involve d²sp³ hybridization, leading to paramagnetism, but the distribution of unpaired electrons deviates from typical expectations due to ligand effects.