Bidentate Ligands

[Tiahna Thomas 2C]

In the Achieve homework for week nine, we look at a problem which includes a bidentate ligand. This confused me at first, so my coordination number was off. I was wondering if there is a way to identify bidentate ligands, or if we are supposed to memorize ones we will commonly see. Thank you!

[Zinnia Kwan 3D]

I feel like you could recognize polydentate ligands by drawing them out because it is polydentate when you see two electrons with lone pairs that are 4 atoms apart (remember the arm-shoulder-shoulder-arm thing Lavelle mentioned in the lecture). However, for one of the problems I remember that EN was the ligand, and I feel like we should memorize that it is bidentate. I feel like it might be useful just to know the really common ones, or at least the ones mentioned in the book: en, dien, and edta.

[Leo Chang 2H]

Hi,

While it may help knowing the more common polydentate ligands, for most of them, I think that you can just determine how many binding sites it will have based on their the number of lone pairs that they have. Since ligands are molecules that bind to the central atom in a coordination compound through the donation of electrons, if a picture of a ligand is provided, you can see how many lone pairs of electrons are present on the ligand to tell you how many binding sites it has. Furthermore, even with molecules like EN, the name is just acronym for the actual molecule; in this case, EN is ethylenediamine. The naming of ligands are usually pretty straight forward, so you could probably just draw out the molecule based on the name if a picture of the ligand is not provided and then count the number of lone pairs.

I hope this helps!