Consider the metal complexes [Ni(en)₃]²⁺ (A), [NiCl₄]²⁻ (B) and [Ni(NH₃)₆]²⁺ (C). Choose the CORRECT option by considering the number of unpaired electrons present in (A), (B) and (C) respectively and the order of frequency of absorption.

Step-by-step solution

The oxidation state of Ni in all three complexes is +2 . The electronic configuration of Ni²⁺ is [Ar] 3d⁸ . In [Ni(en)₃]²⁺ (A), the coordination number is 6 (octahedral geometry). The d⁸ configuration in an octahedral field is t_ 2g ⁶ e_ g ² , which has 2 unpaired electrons. In [NiCl₄]²⁻ (B), the coordination number is 4 with weak field Cl⁻ ligands (tetrahedral geometry). The d⁸ configuration in a tetrahedral field is e⁴ t₂⁴ , which has 2 unpaired electrons. In [Ni(NH₃)₆]²⁺ (C), the coordination number is 6 (octahe