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Equivalent Ligands

  • Page ID
    39301
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    Equivalent ligands or, more completely, chemically equivalent ligands in an organic molecule are like ligands that have identical chemical properties under all or a specified set of conditions. A test known as the replacement test is used to find if two like ligands in a molecule are equivalent.

    eg:

    equivalentligands1a.png

    Apply the replacement test to find if the two hydrogen atoms in 1 are equivalent:

    Step 1:
    Label the two hydrogen atoms in 1 for identification purposes.

    equivalentligands1.png

    Step 2:
    Replace H (a) in 1 with a hypothetical atom (X).

    equivalentligands3.png

    Step 3:
    Replace H (b) in 1 with the same hypothetical atom, X.

    equivalentligands4.png

    Step 4:
    Compare molecules 2 and 3. They are superimposable on each other, meaning that they are identical. Identical molecules have identical chemical properties under all conditions. Since the replacement of H (a) and of H (b) in 1 with the same atom leads to molecules that have identical chemical properties under all conditions, H (a) and H (b) have identical chemical properties under all conditions, i.e., H (a) and H (b) are equivalent under all conditions.

    see also homotopic, enantiotopic, diastereotopic, constitutionally heterotopic


    Equivalent Ligands is shared under a All Rights Reserved (used with permission) license and was authored, remixed, and/or curated by Gamini Gunawardena via source content that was edited to conform to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.

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