In which of the following coordination entities the magnitude of _o (CFSE in octahedral field) will be maximum? (Atomic number Co =27 )

Step-by-step solution

Key Idea: The magnitude of _ c t (the orbital splitting energy) is decided by the nature of ligand Strong field ligand has highest _ oct . The increasing field strength is as I ⁻ < Br ⁻ < Cl ⁻ < F ⁻ < OH ⁻ < H ₂ O < C ₂ O ₄²⁻ < NH ₃ < en < NO ₂⁻ < CN ⁻ The CN ⁻ is the strongest ligand among these, hence the magnitude of _ oct will be maximum in [ Co ( CN )₆ ]³⁻ . Note : The magnitude of _ oct is also decided by oxidation state of the metal ion. Thus, greater the ionic charge on the central metal ion, the greater th