Consider the following coordination complexes: (i) [ Co ( NH ₃ )₆ ]³⁺ (ii) [ Cr ( NH ₃ )₆ ]³⁺ (iii) [ Fe ( CN )₆ ]³⁻ (iv) [ Fe ( H ₂ O )₆ ]²⁺ (v) [ Co ( C ₂ O ₄ )₃ ]³⁻ How many of the given complexes are BOTH inner orbital AND diamagnetic?

Step-by-step solution

To determine if a complex is both inner orbital ( d^2sp^3 ) and diamagnetic (zero unpaired electrons), we analyse the central metal ion's electronic configuration and the nature of the ligand: (i) [ Co ( NH ₃ )₆ ]³⁺ : Co ³⁺ is 3d^6 . NH ₃ acts as a strong field ligand, causing electron pairing ( t_ 2g ^6 e_g^0 ). It forms an inner orbital ( d^2sp^3 ) complex and is diamagnetic. (Satisfies both) (ii) [ Cr ( NH ₃ )₆ ]³⁺ : Cr ³⁺ is 3d^3 . It forms an inner orbital ( d^2sp^3 ) complex regardless of ligand strength ( t_