Consider the following coordination complexes: [ Co ( C ₂ O ₄)₃]³⁻, [ Fe ( NH ₃)₆]²⁺, [ RhF ₆]³⁻, [ Ni ( NH ₃)₆]²⁺, [ PtCl ₄]²⁻, [ CoF ₆]³⁻ The number of complexes that are BOTH diamagnetic AND involve inner d-orbitals ( d ^2 sp ^3 or dsp ^2 ) for hybridization is _______.

Step-by-step solution

Let us evaluate each complex for its hybridization and magnetic behavior: 1. [ Co ( C ₂ O ₄)₃]³⁻ : Co ³⁺ ( 3 d ^6 ). Oxalate ( C ₂ O ₄²⁻ ) acts as a strong field ligand with Co ³⁺ , causing electron pairing. Configuration is t _ 2 g ^6 e _ g ^0 . It is d ^2 sp ^3 hybridized and diamagnetic. (Matches) 2. [ Fe ( NH ₃)₆]²⁺ : Fe ²⁺ ( 3 d ^6 ). NH ₃ acts as a weak field ligand for +2 ions of the 3d series (except Cu ). Configuration is t _ 2 g ^4 e _ g ^2 . It is sp ^3 d ^2 hybridized and paramagnetic. (Does not match)