Consider the octahedral complex [ Co ( H ₂ O )₆ ]²⁺ and the tetrahedral complex [ CoCl ₄ ]²⁻ . Ignoring pairing energy, the ratio of the magnitude of the crystal field stabilization energy (CFSE) of the octahedral complex to that of the tetrahedral complex is :

Step-by-step solution

For the octahedral complex [ Co ( H ₂ O )₆ ]²⁺ : Co ²⁺ is a 3 d ^7 ion. H ₂ O acts as a weak field ligand. The electronic configuration is t_ 2g ^5 e_g^2 . CFSE _ oct = [5(-0.4) + 2(0.6)] _o = -0.8 _o = - 4 5 _o . Magnitude of CFSE _ oct = 4 5 _o . For the tetrahedral complex [ CoCl ₄ ]²⁻ : Co ²⁺ is a 3 d ^7 ion. Tetrahedral complexes are generally high spin. The electronic configuration is e^4 t₂^3 . CFSE _ tet = [4(-0.6) + 3(0.4)] _t = -1.2 _t = - 6 5 _t . Since the crystal field splitting energy in a tetrahedral