Question

Give the number of unpaired electrons in fef6 4- and fecn6 4-

Answer 1

Answer: fef6)4- has 5 unpaired e

Fe(CN)6)4- has 1 unpaired e

Explanation: In both the compounds iron exist as Fe2+

[Fe(f)6]4-

X + 6*-1 = -4

X = -4 + 6 = 2

[Fe(CN)6]4-

X + 6*-1 = -4

X = -4 + 6 = 2

But cyanide ion is a strong field ligand which causes large splitting of d orbitals resulting in pairing of electrons in low energy t2g orbital

While fluorine is weak field ligand it causes less splitting .

Resulting in excitation of electrons to high energy eg orbital