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QJEEAdv18Chdf3b: JEE Advanced 2018 Chemistry - Class 12 JEEAdv18Chdf3b Solution: The correct option(s) regarding the complex [ C o ( e n ) ( N H …

The correct option(s) regarding the complex

[Co(en)(NH3)3(H2O)]3+ (en=H2NCH2CH2NH2) is (are)

Multiple Choice Options

  • A It has two geometrical isomers
  • B It will have three geometrical isomers if bidentate 'en' is replaced by two cyanide ligands
  • C It is paramagnetic
  • D It absorbs light at longer wavelength as compared to [Co(en)(NH3)4]3+

Step-by-Step Verified Solution

Option (A) : Correct. The complex [Co(en)(NH3)3(H2O)]3+ has two following isomers:

JEE Advanced 2018 Paper 2 Offline Chemistry - Coordination Compounds Question 41 English Explanation 1

Option (B) : Correct. When bidentate 'en' is replaced by two cyanide ligands complex [Co(CN)2(NH3)3(H2O)]+ will have three following isomers:

JEE Advanced 2018 Paper 2 Offline Chemistry - Coordination Compounds Question 41 English Explanation 2

Option (C) : Incorrect. Incomplex [Co(en)(NH3)3(H2O)]3+, Co is in + 3 oxidation, that is, [Ar]d6. In the presence given ligands the complex will have low spin, hence, diamagnetic.

Option (D) : Correct. In complex [Co(en)(NH3)4]3+ there is larger gap between t2g and eg than in complex [Co(en)(NH3)3(H2O)]3+. Hence [Co(en)(NH3)3(H2O)]3+ will absorb light at longer wavelength as compared to [Co(en)(NH3)4]3+.

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