Question

${\left[\mathrm{Fe}{\left({\mathrm{H}}_2\mathrm{O}\right)}_6\right]}^{2+}$ and ${\left[\mathrm{Fe}(\mathrm{CN}{)}_6\right]}^{4-}$ differ in :

• A. Geometry, magnetic moment
• B. Magnetic moment and colour
• C. Geometry and hybridisation
• D. None of these

Answer 1

Answer: (B)

$(\mu {)}_I=\sqrt{4(4+2)}=24BM$
${\mu }_{II}=0$
d-d transitions between $t_{2g}\&e_g$ orbitals are different due to $3d^6$ (unpaired) & $3d^6$ (Paired) configurations as shown i.e exhibit different colours.