Now when we talk about structural isomers, we're going to say they consist of two types. We have coordination isomers or linkage isomers. In coordination isomers, we're going to say these are molecules where the anionic ligand and a counter ion and have switched places. So if we take a look here at these two, what can make them coordination isomers? Well, we have an anionic ligand. Let's say our ligand here that's aniotic is the bromide ion and it's going to switch places with a counter ion.
Now the charges of them both have to be the same. So if I have a -1 here, I need to have a -1 ligand attached to the metal. So let's put a chlorine here for us to make its isomer. I just have those switch places now. My bromide ion has come here and my chloride ion is out here. So we swapped in an aniotic ligand for another one.
Now linkage isomers. These are molecules where the connectivity between the ligand and the metal is different. So one example we have here is with thinosinate. Remember, thinosanate has resonance involved and because of that we could either have the nitrogen be the negative end or the sulfur being the negative end. When we talked about donor atoms, we said that the negatively charged atom within a ligand would act as the donor atom, and because nitrogen or sulfur can be negatively charged, either one could be the donor atom.
This will result in linkage isomers 1 where we have these sulfurs directly connecting to our silver ion or one where the nitrogen directly connects to our silver ion. So these will be two linkage isomers and as a result of the ligand itself possessing resonance meaning multiple elements could be the donor atom. So just keep in mind when we talk about structural isomers, we're talking either about coordination isomers or linkage isomers.