Remembering polydentates

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tchar96_1F
Posts: 14
Joined: Fri Sep 26, 2014 2:02 pm

Remembering polydentates

Postby tchar96_1F » Sun Nov 23, 2014 4:07 pm

Hi,

I was wondering if we are expected to know which compounds are polydentates (bidentate, tridentate, etc.) so we can figure out the coordination number?

Thanks!

AmirMahmoud_1J
Posts: 9
Joined: Fri Sep 26, 2014 2:02 pm

Re: Remembering polydentates

Postby AmirMahmoud_1J » Mon Nov 24, 2014 6:06 pm

You don't need to memorize them. You can just work them out by doing the lewis structure and finding the lone pairs, that way you don't have to memorize anything. I personally think its good to have an idea of the number of bonds the compounds that we use in class such as edta.

RaquelAvalos1K
Posts: 35
Joined: Fri Sep 26, 2014 2:02 pm

Re: Remembering polydentates

Postby RaquelAvalos1K » Fri Nov 28, 2014 6:30 pm

So the number of sites a ligand can bond to are determined by number of lone pairs?

GinaYoung1L
Posts: 16
Joined: Fri Sep 26, 2014 2:02 pm

Re: Remembering polydentates

Postby GinaYoung1L » Fri Nov 28, 2014 10:59 pm

The number of lone pairs (with each pair on separate atoms) is indeed helpful in determining the number of binding sites one ligand can have. For instance, in the chemical formula for diethylenetriamine, NH2CH2CH2NHCH2CH2NH2, there are three nitrogens. The three nitrogens each have a lone pair if you can imagine its Lewis structure without writing it out. The ligand is expectantly a tridentate.

However, you have to be careful if the lone pairs are in close proximity (such as in H2O.) The H2O structure has two lone pairs on the same atom, oxygen. Therefore, only one lone pair can physically act as a binding site. H2O is a monodentate rather than a bidentate.

RaquelAvalos1K
Posts: 35
Joined: Fri Sep 26, 2014 2:02 pm

Re: Remembering polydentates

Postby RaquelAvalos1K » Sat Nov 29, 2014 3:36 pm

I'm having trouble making or finding a lewis structure for dien. How is it that the central N also has a lone pair?


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