Question

All the metal ions contains t2g6 eg0 configurations. Which of the following complex will be paramagnetic?

• A. [FeCl(CN)4(O2)]4-
• B. K4[Fe(CN)6]
• C. [Co(NH3)6]Cl3
• D. [Fe(CN)5(O2)]-5

Answer 1

Answer: (A)

$FeCl(CN)4(O2)$4-

Answer 2

(1) [FeCl(CN)4(O2)]4– ; O2 is O22–; CN– is strong field ligand, so compels for the pairing of electrons.

Fe3+ ® 3d5 ;

(2) K4[Fe(CN)6] ; CN– is strong field ligand so compels for the pairing of electrons.

Fe2+ ® 3d6 :

(3) [Co(NH3)6]Cl3 ; NH3 is strong field ligand and 3d6 configuration has higher CFSE compelling for the pairing of electrons.

Co3+ ® 3d6 :

(4) [Fe(CN)5(O2)]5– ; O2 is O22– ; CN– is strong field ligand so compels for the pairing of electrons

Fe2+ ® 3d6 :