Which of the following pairs correctly represents an 'inner orbital diamagnetic' complex and an 'outer orbital paramagnetic' complex, respectively?

Step-by-step solution

In [Fe(CN)₆ ]⁴⁻ , the central metal ion is Fe²⁺ , which has a 3d^6 electronic configuration. Since CN^- is a strong field ligand, it causes the pairing of electrons, resulting in a t_ 2g ^6 e_g^0 configuration. This gives d^2sp^3 hybridization (inner orbital complex) with zero unpaired electrons, making it diamagnetic. In [Fe(H₂O)₆ ]²⁺ , the central metal ion is also Fe²⁺ ( 3d^6 ). However, H₂O is a weak field ligand, so no forced pairing occurs. The configuration is t_ 2g ^4 e_g^2 , leading to sp^3d^2 hybridizatio