COMEDK202510 May 2025Evening ShiftChemistryCoordination CompoundsActual
The correct order of spin only magnetic moments among the following is: [Given: Atomic numbers: Mn =25, Fe =26, Co =27 ]
Options
- A[ MnCl ₄ ]²⁻> [ CoCl ₄ ]²⁻> [ Fe ( CN )₆ ]⁴⁻
- B[ MnCl ₄ ]²⁻> [ Fe ( CN )₆ ]⁴⁻> [ CoCl ₄ ]²⁻
- C[ Fe ( CN )₆ ]⁴⁻> [ CoCl ₄ ]²⁻> [ MnCl ₄ ]²⁻
- D[ Fe ( CN )₆ ]⁴⁻> [ MnCl ₄ ]²⁻> [ CoCl ₄ ]²⁻
Correct answer
A. [ MnCl ₄ ]²⁻> [ CoCl ₄ ]²⁻> [ Fe ( CN )₆ ]⁴⁻
Step-by-step solution
For [ MnCl ₄ ]²⁻ : Mn is in +2 oxidation state ( d^5 configuration). Since Cl ⁻ is a weak field ligand, the electrons remain unpaired. Number of unpaired electrons n = 5 . Magnetic moment = n(n+2) = 5(7) = 35 5.92 BM. For [ CoCl ₄ ]²⁻ : Co is in +2 oxidation state ( d^7 configuration). Since Cl ⁻ is a weak field ligand, the electrons remain unpaired. Number of unpaired electrons n = 3 . Magnetic moment = 3(5) = 15 3.87 BM. For [ Fe ( CN )₆ ]⁴⁻ : Fe is in +2 oxidation state ( d^6 configuration). Since CN ⁻ is a stro