CBSE Class 12 Chemistry 2014 Outside Delhi Set 1 Solved Paper

Question : 23

Total: 30

(i) Write the IUPAC name of the complex [Cr(NH3)4‌Cl2]‌Cl.
(ii) What type of isomerism is exhibited by the complex [Co(en)3]3+ ?
(en = ethane-1, 2-diamine)
(iii) Why is [NiCl4]2− paramgnetic but [Ni(CO)4] is diamagnetic
(At. nos.: Cr=24,Co=27,Ni=28 )

Solution:

(i) The IUPAC name of [Cr(NH3)4‌Cl2]‌Cl is Tetraam minedichlorochromium(III) chloride.
(ii) The isomerism exhibited by this complex is the optical isomerism.
(iii) The oxidation state of Ni in [NiCl4]2− is +2 . Since chloride is a weak field ligand, it does not cause electron pairing up in opposition to Hund's maximum multiplicity rule. As a result, Ni's valence d-orbitals contain two unpaired electrons, giving the complex its paramagnetic properties. On the other hand, carbonyl is a strong field ligand and causes electron partnering up in opposition to Hund's maximisation rule. As a result, there are no unpaired electrons and the complex is hence diamagnetic.

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