Question

The correct order of the number of unpaired electrons in the given complexes is
A. \([Fe(CN)_6]^{3–}\)
B. \([FeF_6]^{3–}\)
C. \([CoF_6]^{3–}\)
D. \([Cr(oxalate)_3]^{3–}\)
E. \([Ni(CO)_4]\)
Choose the correct answer from the options given below:

• A. A < E < D < C < B
• B. E < A < B < D < C
• C. E < A < D < C < B
• D. A < E < C < B < D

Answer 1

The Correct Option is C

The order of unpaired electrons can be determined by considering the electronic configurations of the metal centers in the complexes: \[ \text{Fe}^{3+} (3d^5) \quad \text{(for Fe(CN)$_6^{3-}$)} \] \[ \text{Fe}^{3+} \quad \text{(for FeF$_6^{3-}$)} \] \[ \text{Co}^{3+} \quad \text{(for CoF$_6^{3-}$)} \] \[ \text{Cr}^{3+} \quad \text{(for Cr(oxalate)$_3^{3-}$)} \] \[ \text{Ni} \quad \text{(for Ni(CO)$_4$)} \] After considering the ligand field effects (Weak Field Ligand vs Strong Field Ligand) and the electronic configurations, the order of unpaired electrons is: \[ E < A < D < C < B \]