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Thread: Complex ions

  1. #1 Complex ions 
    Forum Ph.D. Heinsbergrelatz's Avatar
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    can anyone briefly outline the answers to these questions?

    is acidic in solution form? if so why?

    Also the ligand ammonia can form a complex ions with Cobalt(II) ion but methane cant, Why? Is it because methane is already stable and has no lone pairs of electrons to form a dative bond with the Central metal ion?(btw this is my answer)

    thank you


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  3. #2  
    Moderator Moderator AlexP's Avatar
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    Your answer sounds right to me.

    Considering that chromium hydroxide, iron hydroxide, and copper hydroxide are not strong bases, what do you think Cr, Fe, and Cu ions will do in solution? Think about this and see if you can arrive at an answer.


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  4. #3 Re: Complex ions 
    Forum Freshman Silex7's Avatar
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    Quote Originally Posted by Heinsbergrelatz
    can anyone briefly outline the answers to these questions?

    is acidic in solution form? if so why?
    Cr(III) is highly inert complex due to its high Ligand Field Stabilization Energy (LFSE) , hence rate of displacement of ligands for Cr(III) complexes is too much slower than it would be for Cr(II) (labile complex), so I assume that this complex won't easily displace Cl- ions with (H+) ions of water in solution, hence it won't be acidic at all ..this is not the ultimate answer of your question, this is just my humble view as a result of my stepped conclusion.

    Quote Originally Posted by Heinsbergrelatz
    Also the ligand ammonia can form a complex ions with Cobalt(II) ion but methane cant, Why? Is it because methane is already stable and has no lone pairs of electrons to form a dative bond with the Central metal ion?(btw this is my answer)

    thank you
    That has to do with ligand factors dependent which are,
    its Basicity that correlates well with ligand nucleaophilicity towards metal center (CoII).. ammonia here is much more basic than methane so its preferred.

    Polarisability, when the repulsion reduced between the electron pair of the nucleophilic ligand (NH3 in this case) and the metalic center (CoII) due to the ability of the entering group to accept electrons from the metal center into a suitable pai orbital..in our case here ofcourse ammonia is more polarised than the methane due to its lone pair and since it is a soft ligand (easily polarised ligand -can accept free electrons easily from the metal) hence ammonia is preferred.

    Also,heavier metal elements (CoII) ease the process of polarization with ammonia.

    i hope this would help alittle.
    "Nothing can be accepted in this world, if it did not pass the mathematical proof."

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