Consider the following isomers [Cr(NH3)2Cl4]-.

(a) Label the isomers as cis or trans.

(b) Which isomers are identical, and which are different?

(c) Do any of these isomers exist as enantiomers? Explain.

Video transcript

All right. Hi, everyone. So this question says that the structures below show isomers of PT CO two F two. Part one categorize each isomer as either cis or trans. Part two identify which isomers are identical. And part three identify the pair of isomers that exist as enantiomer. So as you can see, we have four different answer choices, proposing different possibilities for both. Uh excuse me, for parts 12 and three. So let's go ahead and get started and recall that for the first parts of the question we're looking for stereo isomers, right? And stereo isomers can fall under two distinct categories after I scroll up a bit, right. The first are anant tir and the second category are diarios. Now in N two mirrors referred to stereo isomers that happen to be mirror images of each other where is dice, stereo mirrors are stereo isomers that happen to be non mirror images of each other. And for the record rate, cis trans isomers are considered to fall under the category of di stereo mirrors because they would not be mirror images of each other. So if we consider the structures of the ligands provided in this question, we have to consider the orientation of each type of ligand relative to each other, right? Because for both A through D or not both but structures A through D, we have platinum in the center of all structures and we have two types of ligands, right? We have two co ligands and two fluorine lids. So a specific configuration, a specific structure is considered to be cis when the ligands are on the same side relative to the center. By contrast, it's considered trans, if the two ligands are on opposite sides of each other, right. So if we consider structure A for a moment relative to the atom of platinum in the center, our fluorine ligands are on opposite ends and so are the co leggins as well. So because they're opposite relative to each other, right structure A or isomer A is going to be trans. So when we consider structure be in the same way, structure B has its ligands on the same side relative to our platinum in the center. Therefore, right oops structure B is going to be cysts, excuse me. And structure C once again has our ligands on opposite ends of our center, which means that C similar to A is going to be trans and D once again is going to be sis because we can see that the spheres of the same color are on the same side relative to our platinum in the center. So this is going to answer part one right structures A and C are trans, whereas B and D are sis, so now let's go ahead and focus our attention on the second part of the question in which we identify, which isomers are identical to each other. Now, to answer this question, we have to recall two things. Number one, there are only two types of ligands in this compound specifically. And number two, both types of ligands happens to be mono dentate. And so what that means is that for each ligand that we have in this compound, only one atom is coordinating with the central metal ion in this case, platinum. So because of this, all cyst structures are going to be identical and all trans structures are going to be identical as well. And the reason for this is because they're essentially going to be the same exact molecule viewed in different perspectives, right. So for example, A and C are both trans, meaning they're going to be identical to each other because you can rotate either of the two structures to make it look like the other one. And this is illustrated if you can imagine rotating or structure A here so that it looks the same as C. So therefore, right to answer part two of the question A and C are identical and B and D are identical to each other because they have the same configuration, right, either they are both Ciss or they are both trans. So now we can go ahead and compete. The third part of the question in which we identify the pair of isomers that exist as an numer. Now recall it earlier on in this video, we first identified which isomers were cis or trans. And what I want to point out here is that ac trans relationship actually means that they're going to be die stereo mi not in an tumors, right. So because our cis structures are identical and the trans structures are identical, that actually means we have two distinct complexes indicating that they are di stereo mirrors and not an Antos. So what that means is that there is no possibility of us being able to rotate the isomers in such a way that they're going to appear like mirror images of each other in this case, that is not going to be possible. So what that means is that for part three of the question, we're not actually going to observe any pairs that will exist as anant meres because instead they're all die stereo meres. So with all this in mind, right, our answer is going to be option A in the multiple choice because for part one, right A and C are trans, whereas B and D are sis for part two A is identical to C and B is identical to D. And for part three, none of the isomers exist as anant tumors because they are, in fact Dier Mes So, with that being said, if you stuck around to the end, thank you so very much for watching. And I hope you found this helpful.