CBSE Class 12 · 2007 · Foreign · Coordination CompoundsShort Answer

a) Illustrate the following with an example each:
i) linkage isomerism
ii) coordination isomerism
b) Why is [NiCl

_{4}

]

^{2 -}

paramagnetic? (Ni = 28)

Solution

(a)(i) Linkage isomerism — an ambidentate ligand binds through different atoms:

[Co (N H_{3})_{5} (N O_{2})] C l_{2} (N -bonded) and [Co (N H_{3})_{5} (ONO)] C l_{2} (O -bonded)

(ii) Coordination isomerism — ligands exchanged between cationic and anionic spheres:

[Co (N H_{3})_{6}] [Cr (CN)_{6}] and [Cr (N H_{3})_{6}] [Co (CN)_{6}]

(b) Ni

^{2 +}

= 3d

^{8}

. Cl

^{-}

is a weak-field ligand, so no pairing occurs; the complex is tetrahedral (sp

^{3}

) and the d

^{8}

configuration retains \textbf{2 unpaired electrons} — hence paramagnetic.

CBSE Class 12 Board · 2007 · Foreign · Subjective