Which of the complexes or complex ions has geometric (cis

Question

Which of the complexes or complex ions has geometric (cis or trans) isomers?

Accepted Answer

Hi, everyone. Welcome back. Let's look at our next question. It says which statement about the relationship between the structures of the complex ion and our ion has an overall charge of positive one and it has a Cobalt atom, two water liens and two catechol ligands abbreviated lowercase cat. And our questions again asking which statement about the relationship between the structures of this ion is incorrect. And we have four different structures of our given complex. And then we need to choose the incorrect statement among choice. A one and two are cis trans isomers B two and three are an Antium C one and four are dimers or D one and three are cis trans isomers. So cyst trans isomers are kind of the easiest to start with the easiest to evaluate. As we recall, we would start with when we have we have two and two ligands, but one of our ligands, the cat coate is by dentate. So let's look at our Monod dente water ligand. We have two of them. They will be a trans arrangement if they are 180 degrees apart opposite from each other. And this arrangement, if they're adjacent to each other or 90 degrees apart. So in choice, a, we're supposed to evaluate whether one and two R cy trans isomers. And indeed, when we look at molecule one, we see that the water ligands are 180 degrees apart opposite from each other. And in structure number two, they are adjacent to each other 90 degrees apart. So we have structure number one being trans structure, number two being sis. But other than that, then they have the two water ligands, the two cat coate ligands around that central Cobalt. So they are cist trans isomers. So statement A is true. And since we're looking for an incorrect statement, it won't be our answer. We have one other statement that asks about cis trans isomers. A statement D asks whether one and three are cyran isomers. So we've already seen that structure one is a trans isomer. Let's look at structure number three. And we see instruction number three, we have two adjacent water molecules. So that would be a cyst arrangement and therefore one and three are also cys trans isomers. So this is another true statement and therefore another answer that will eliminate. So now let's look at choice B it says two and three are an anti MERS. Let's recall that an anti are non superimposable mirror images. So we need to evaluate these. So let's look at number two. And I'm going to draw a very simplified structure to make it a little easier. The cat coate being a little bulky, it can sometimes be a little tricky as you're trying to see. Imagine rotating it around. I have my basic octahedral structure with cobalt in the middle. And I know in structure number two, I have my sis arrangement of water ligands draw them there. And then for my cat coate, I'm just going to draw my two oxygens and then I'll just draw an arc connecting them representing the rest of my structure. Recalling that cate is a symmetrical molecule, the plane of symmetry through it. And then I'll add my other cate that's on within the square plane. So first, I will draw the mirror image of this molecule and then we will see if it's super imposable to determine whether there is an anti, if it's an a chiral molecule, we would not have an anti. And then does that mirror image match up with structure number three. So let's draw our mirror image. And can we superimpose these on each other? So I will imagine rotating my first structure, my structure number two to see if I can get it to be identical to the mirror image. So as I draw my octahedral structure here, I'm going to see what would make a rotation that might cause them to match up. Well, a logical thing to start out with would be that Catechol ligand that's within the square plane. It's on the left side in my written initial structure. And on the right side of my mirror image. So let's imagine rotating this whole molecule 180 degrees to put that calculate over on the right side. What happens to the other ligands? Well, the water ligand on top stays the same. That was my axis of rotation. Then part of that oxalate on the bottom stays there, not oxalate, excuse me, catechol, the oxygen atom from the catechol stays on the bottom. But the it was linked to an oxygen atom. The other part of that cate was in the front, right, rotated around 100 80 degrees. That will be in the back left. So that link will be going from the bottom to the back left and then our remaining water molecule will move from the back right to the front left. So you can see that we try and rotate this so that, that a cat coate in the square plane matches up. This is not a super imposable mirror image. So we have an anti ierse here. So these are an an timorous. So the last thing we have to check is does our mirror image match structure three because we're trying to evaluate our two and three in ante MERS. And indeed, when we look over at structure number three, it has adjacent cis water ligands on the top and the back left, it has a catechol within the square plane on the right. And then the remaining catechol with a link from the bottom oxygen to the front left. So two and three are indeed an an timorous. This is a true statement. And so therefore, choice B cannot be our answer. Well, by process of elimination, we know choice C must be the answer. This must be an incorrect statement. It says one and four are ditherers. So dimers, we have the same atoms bonded to the same central atom, but different arrangements and space around it. So let's evaluate structure one and structure four. Well, first thing we'll notice looking at structure four is that it also has just like structure one, a trans arrangement of the water leggings. And that makes it pretty easy to see given that cat coate is also a symmetrical uh ligand. And so the cata Coates are opposite from each other. We have this symmetrical overall molecule. And indeed, we could take structure four, rotate it. So those two trans water molecules are at the top and the bottom our catechol ligands would then be in the square plane. And we can see that one and four are not ditherers, they are the identical structure, the identical molecule. So statement C is indeed false. And choice C is therefore our answer as to which statement about the relationship between these structures is incorrect, that one and four are dia see you in the next video.

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Which of the complexes or complex ions has geometric (cis or trans) isomers?

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