Among the following, the pair of coordination complexes that exhibit the exact same spin-only magnetic moment is:

Step-by-step solution

For [ Cr ( H ₂ O )₆]²⁺ , the central metal ion is Cr ²⁺ , which has a 3 d ^4 electronic configuration. Since H ₂ O is a weak field ligand, the configuration is t _ 2 g ^3 e _ g ^1 , giving 4 unpaired electrons. For [ Fe ( H ₂ O )₆]²⁺ , the central metal ion is Fe ²⁺ , which has a 3 d ^6 electronic configuration. With the weak field ligand H ₂ O , the configuration is t _ 2 g ^4 e _ g ^2 , giving 4 unpaired electrons. Since both complexes have 4 unpaired electrons, they have the same spin-only magnetic moment ( = 4(