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isomerism in complexes

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  • hoay's Avatar
    189 posts since Jul '11
    • http://pastpapers.papacambridge.com/view.php?id=Cambridge%20International%20Examinations%20%28CIE%29/AS%20and%20A%20Level/Chemistry%20%289701%29/2016%20Jun/9701_s16_qp_42.pdf

       

      For Q.4(a)(iii) the complex given does not show cis-trans. The marking scheme says  that its mirror images are superimposable. But how ? I think the mirror images are non-superimposable.  when we say non-superimposable we say with reespect to 3 -dimensional arrangement. In 3-dimensional they would be different. 

       

  • Moderator
    H2 Chemistry @ BedokFunland JC (near VJC & TJC)
    UltimaOnline's Avatar
    15,164 posts since May '05
    • Originally posted by hoay:

      http://pastpapers.papacambridge.com/view.php?id=Cambridge%20International%20Examinations%20%28CIE%29/AS%20and%20A%20Level/Chemistry%20%289701%29/2016%20Jun/9701_s16_qp_42.pdf

       

      For Q.4(a)(iii) the complex given does not show cis-trans. The marking scheme says  that its mirror images are superimposable. But how ? I think the mirror images are non-superimposable.  when we say non-superimposable we say with reespect to 3 -dimensional arrangement. In 3-dimensional they would be different. 

       


      The mirror image is indeed superimposable onto the molecule itself. Imagine the mirror image, then rotate the mirror image 180 degrees. It becomes the molecule itself, ie. superimposable.

  • hoay's Avatar
    189 posts since Jul '11
    • and if on rotating 180 it doe not match the original moleucle its non-superimposable?

      If we replace one of the  bidentate ligands with two different monodentate then there would be optical isomers and not cis-trans isomers? Is'nt ? 

      Edited by hoay 04 Feb `18, 4:31AM
  • Moderator
    H2 Chemistry @ BedokFunland JC (near VJC & TJC)
    UltimaOnline's Avatar
    15,164 posts since May '05
    • Originally posted by hoay:

      and if on rotating 180 it doe not match the original moleucle its non-superimposable?

      If we replace one of the  bidentate ligands with two different monodentate then there would be optical isomers and not cis-trans isomers? Is'nt ? 


      Yes (but can be any degree, not necessarily 180) and yes.

  • hoay's Avatar
    189 posts since Jul '11
    • If sulfato SO42- is bidentate ligand along with ethylenediamine then it has no isomers as the case with Pt complex above?

  • Moderator
    H2 Chemistry @ BedokFunland JC (near VJC & TJC)
    UltimaOnline's Avatar
    15,164 posts since May '05
    • Originally posted by hoay:

      If sulfato SO42- is bidentate ligand along with ethylenediamine then it has no isomers as the case with Pt complex above?


      Yes.

  • Galateawoodson's Avatar
    1 post since Apr '18
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