Consider the following coordination complexes: [ CoF ₆]³⁻, [ Fe ( H ₂ O )₆]³⁺, [ Cr ( H ₂ O )₆]³⁺, [ Co ( NH ₃)₆]³⁺, [ Ni ( NH ₃)₆]²⁺ The total sum of unpaired electrons present ONLY in the complexes that exhibit sp ^3 d ^2 hybridization is _______.

Step-by-step solution

Let us evaluate the hybridization and number of unpaired electrons for each complex: 1. [ CoF ₆]³⁻ : Central metal is Co ³⁺ ( 3 d ^6 ). F ^- is a weak field ligand, so pairing does not occur. Configuration is t _ 2 g ^4 e _ g ^2 . It uses outer d-orbitals for sp ^3 d ^2 hybridization. Number of unpaired electrons = 4. 2. [ Fe ( H ₂ O )₆]³⁺ : Central metal is Fe ³⁺ ( 3 d ^5 ). H ₂ O is a weak field ligand. Configuration is t _ 2 g ^3 e _ g ^2 . It exhibits sp ^3 d ^2 hybridization. Number of unpaired electrons = 5.