What is the systematic name for each of the following molecules or ions? Include cis or trans prefixes for diastereoisomers. Platinum is Pt(II) in square planar complexes and Pt(IV) in octahedral complexes.

(1)

(2)

(3)

(4)

Video transcript

Hi, everyone. Welcome back. Here's our next problem. It says name each of the following co ordination complexes assigned CIS or trans. If applicable fe is ee Roman numeral two in octahedral complexes and Fe Roman numeral one in square planar complexes. We're given four different possible structures, different geometries, different ligands, different numbers of those ligands. The atoms in them are represented by colored balls, a yellow ball representing fe a blue ball representing H2O a gray ball representing CN A purple ball representing BR and two red balls linked by an arc representing the bate ligand NH two C two CH two NH two, which is ethylene diamine in which the red balls represent the two nitrogen atoms that do the bonding with the metal atom. And then our answer choices A through D are just different possible names for our four different structures. But I'm not going to read out all those names all at once. We'll work through them one by one as we think of the name for our compounds. So let's recall the general order in which we name a compound first. We name the Liggins in alphabetical order. So I'll write an ABC order, we give them a correct prefix to show the number. Remembering that if our ligand doesn't have its own prefix already, we use those prefixes by or die, excuse me, dye, try, etcetera. If there's already a prefix in a ligand name such as an ethylene diamine, we use those prefixes bis, Tris Tetris, et cetera. And then if our ligand happens to have a negative charge, we give it the ending O so an O ending if it's negative, but we don't change it. Of course, if it's positive or neutral. And then after we name all of our ligands, then we name the metal Adam, we use Roman, the Roman numeral in parentheses. And I've just put parentheses around the word Roman numeral to remind us to show the oxidation state of that atom. And if our complex is a, an anion, we use the A TE ending in our middle name. So the A T ending, if it's an anion, we don't change the middle name if it's a cion or it's neutral. If we had counter ions, we would name them last, but none of our complexes have a counter ion. So let's go ahead and think of each of these names for structure number one, we have, of course, our iron in the center, we have an octahedral complex. So this is going to be fe two, we have five water ligands and then one bromide ligand. So in terms of alphabetical order, we need to remember that for water. We use the name Aqua when it's a ligand. So that begins with a, as opposed to the bromine atom, which begins with B. So we are going to name our water ligands first. There are five of them. So we need to use the prefix Penta. We are not worrying about cis or trans because we just have the one bromine. So that isn't going to come into play. So we have panta aqua, bro. I mean there's just one water, of course, is neutral. Bromine has a charge of negative one, since it's negative, we have to give it that o ending. So its name is bromo. So we've taken care of our ligands. We just need our metal ion, it's iron two. We know that we have a Roman numeral, but we need to think about the overall charge of our complex. Is it an, am I? So let's add up the overall charges. We have water is zero. So we'll do zero plus the charge from the bromo, which will be negative one plus the charge from our iron, which as we know is two. So plus two. So our overall charge of the complex will be positive one. So we don't need to change the name. So we write and important to remember the metal name, no spaces. It just runs in there with no spaces. So we have iron and then Roman numeral two in parentheses. Penta Aqua bromo iron two. So let's look at our answer choices to see if we can eliminate any of them. Choice. A for number one says Penta aqua bromo frate two, but this would not be correct because we'd only use frate if our complex was an anion. So eliminate choice. A choice B has Penta aqua bromo iron two as does choice C and choice D as their name for number one, but we've at least eliminated one there. Now let's move on to structure. Number two, structure number two is square planar, only four ligands. So we know iron must be iron one. We have two water ligands and two CN ligands. So CN has a charge of negative one. So when we name our ligands, we will use water first beginning with a, there's two of them. When we have two, we need to remember to label whether it's sis or trance. The two water ligands on our molecule are adjacent to each other at a 90 degree angle. So this would be a cyst and we write that in italics. So Sisson and hyphen now our water, there's two of them. So it's going to be die aqua. Now we get two are cyanide ligand. It's got a negative one charge. So we need that o ending and there's two of them. So it will be die. Cyano got all of our ligands. We need our metal, we know our Roman numeral. We just need the overall charge to see if it's an anion. So our two Cyan origins, we'll have a charge of negative one. So we'll have negative one, multiplied by two. Our waters are neutral. So plus zero, then our iron is a positive one. So plus one. So the overall charge of this complex will end up being negative one. So this is an anion. So our iron needs that a te ending with iron, you use the Latin name. So it's fate and one. So we have Sis Di Aqua Disano fri one. So back to our answer. Choices and Choice B complex two is named trans di aqua di Cyano iron one. While the trans is wrong as is the name iron. So choice B is incorrect twice says sis di Aqua Diano ferret one. So that's correct. And D says Sis di Aqua di Cyano Ferri one. So also correct. But we've eliminated Choice B now we're on to complex number three. It's an octahedral complex. So this will be iron too. We have two water ligands and then we have two of our ethylene diamine, our bent ligand. We do need to label cis or trans, since our waters could be adjacent or opposite this case, our waters are opposite 180 degrees apart. So this will be trans that should be an italics. And then we need die aqua for the two waters. Then we have two of our ethylene diamine ligand. But as we mentioned earlier the ethylene diamine already has an a prefix indicating number. So that needs to say this. And then we put in parentheses, Ethylene diamine. So we've dealt with all of our ligands. We just need to name our central iron. So let's think about the, the overall charge on our complex. Well, water and ethylene diamine are both neutral. So zero plus zero plus the iron charges two equals positive two. So it will just be iron. And then in parentheses two. So trans dy aqua biss ethylene diamine iron two. So we look at choice C. That is indeed what we have when we look at choice D however, its trans di aqua bis ethylene diamine fate two. But again, we wouldn't use ferret because we don't have an airline. So we've eliminated choice D we know that C must be our correct answer. Now, on a test, I wouldn't go any further, but just to be thorough here and really go through all our different complexes. We'll just quickly name number four here. Number four is square planar. So we're talking about iron one, its got two waters and one ethylene diamine. Now we have two water ligaments with ligas, excuse me, but we don't need to use CIS or trans because Ethylene diamine being a bent ligand can only be in two adjacent spots. So the water must also be adjacent. You don't need trans or cysts to disambiguate the arrangement there. So we don't need that we just need to indicate there are two di aqua again, a comes first and then we have just one ethylene die. I mean, let's look at our overall charge. Well, just like the last structure, we just have neutral water. So zero plus zero for neutral ethylene diamine plus one for our iron, our overall charge is positive one. So it's iron one. Now we can confirm that that is the name for number four in choice C di aqua ethylene diamine iron one. So our answer choice is indeed choice. C I'm not going to read all those names all the way through since we talked each of them through. But Choice C has the correct name for all four structures. See you in the next video.