Which one of the following coordination complexes exhibit the lowest value of magnetic moment (in BM)?

Step-by-step solution

(I) [ Cr ( CN )₆ ]³⁻, Cr ³⁺ 3 d^3 CN is a strong field ligand. Number of unpaired e⁻=3 N= n(n+2) = 3(3+2) = 15 BM (II) [ Mn ( CN )₆ ]³⁻ ; Mn ³⁺ 3 d^4 CN is a strong field ligand. Number of unpaired e⁻=2 N= 2(2+2) = 8 BM (III) [ Fe ( CN )₆ ]³⁻ ; Fe ³⁺ 3 d^5 CN is a strong field ligand. Number of unpaired e⁻=2 N= 2(2+2) = 8 BM (IV) [ Co ( CN )₆ ]³⁻, Co ³⁺ 3 d^6 CN ⁻ is a strong field ligand. Number of unpaired e⁻=0 N=0 Hence, minimum value of magnetic moment is for [ Co ( CN )₆ ]³⁻ .