Polydentate Ligands

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SLai_1I
Posts: 112
Joined: Wed Sep 30, 2020 9:52 pm

Polydentate Ligands

Postby SLai_1I » Fri Dec 04, 2020 7:32 pm

What are ways to tell if a ligand is polydentate?

Selena Quispe 2I
Posts: 129
Joined: Wed Sep 30, 2020 10:01 pm
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Re: Polydentate Ligands

Postby Selena Quispe 2I » Fri Dec 04, 2020 7:43 pm

You can tell if a ligand is polydentate if it has 2 or more binding sites. A great example of this is ethylenediamine which has two binding sites at the Nitrogens, it is considered to be bidentate! Another example is diethylenetriamine which has three binding sites as the molecule has three nitrogen binding sites! Attached below is images of Ethylenediamine and Diethylenetriamine (imagine the lone pairs on diethylenetriamine as the image did not include them). I hope this helps!
Attachments
Diethylenetriamine.png
Diethylenetriamine.png (1.28 KiB) Viewed 30 times
Ethylenediamine.jpg
Ethylenediamine.jpg (16.72 KiB) Viewed 30 times

CesarLec1
Posts: 67
Joined: Wed Sep 30, 2020 9:49 pm

Re: Polydentate Ligands

Postby CesarLec1 » Fri Dec 04, 2020 10:23 pm

A great way to find out if it is polydentate is by drawing the lewis structure of the molecule and then filling in the bonds and the free pairs. Once you have drawn them correctly you can easily find where it can bond due to the free pair electrons and if it is more than 2 then it is polydentate.

Ayesha Aslam-Mir 3C
Posts: 122
Joined: Wed Sep 30, 2020 9:43 pm

Re: Polydentate Ligands

Postby Ayesha Aslam-Mir 3C » Sat Dec 05, 2020 4:28 pm

Since a ligand bonds in a chelating complex by donating a lone pair, look for several atoms with one pairs within the same molecule; two lone pairs on the same atom can't bond to the metal atom (lone pair e- repulsion) but otherwise two different Nitrogens with lone pairs, for example, in the same molecule could show bidentate nature, or two places to bond as ligands, in that compound. It could help to draw the Lewis structures out, and/or calculate formal charges on atoms like nitrogen to determine is there is a lone pair to be donated.


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