Naming Coordination Compounds - Video Tutorials & Practice Problems
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concept
Ligand Naming
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Naming coordination compounds uses a systematic set of rules known as IUPAC, and one important portion of this naming system is the naming of ligands. Now here we're gonna say ligands themselves can either be anions or neutral molecules. Remember, we've said before that there are such things as cationic ligands, but we're not gonna cover those types of ligands within this general chemistry course. So for right now, ligands can either be negatively charged or neutral. Now if we take a look here on our anionic or negatively charged ligand side, for example here, bromide ion, its ligand name is bromo. Oxide is o two minus. In terms of its ligand name, it's oxo. Hydroxide becomes hydroxo. Cyanide becomes cyano. So we can see a kind of theme being formed where we have this o ending of the negatively charged ligand. Azide ion is n 3 minus 1. Here, it would be called isoto, and then nitro is nitrate nitrite is nitro, oxalate anion is oxalato, and then carbonate is carbonado. For our neutral side, here we have the ligand name already. We just have to determine what the formula will be for our ligand. Aqua is water, so h two o. Amine is the ammonia molecule. Carbonyl is CO, carbon monoxide. We have nitroso, which is n o. And then finally, we have ethylenediamine. Here, realize that we have this numerical prefix within it. We'll see how that plays a role in our naming of these different types of ligand structures. Ethylene diamine is just e n for short. So these are the most important and most commonly used negatively charged ligands and neutral ones.
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example
Naming Coordination Compounds Example
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In this example question, it says, write names of all ligands and complex ions. So here we have a silver connected to 2 of these ethylenediamine or bidentate ligands, then we have 2 chloride ions. Right. So step 1 here is we name ligands in alphabetical order. If a ligand is an anion, so negatively charged, you change the ending to o. So here, if we take a look, who is our negatively charged ligand here? It would be the chloride ion. So here, if we're saying chloride is this, Cl minus, then its name would become chloro. Next, if a ligand is neutral, name is molecules with exceptions. Here, our neutral ligand would be this, basically, this ethylenediamine, the e n. So that'd be this portion right here that we're talking about in terms of our neutral ligand here. So here, that would just be, ethylenediamine as its name. And then when more than one identical ligand, we'll use the prefixes of di for 2, tri for 3, tetra for 4. Usually, we won't see beyond that, so we don't worry about too much beyond that. But if it does happen, we'll we'll see that when it occurs. So here, if a ligand has a prefix in the name, so ethylenediamine, di here is a numerical prefix, then you place the ligand in parenthesis and use the prefixes of -bis, if there's 2 of them, tris, if there's 3 of them, and tetra kiss, if there's 4. K? Again, we see this with ethylenediamine because it has the di in its name, that numerical prefix. With all this information, how would we name these 2 ligands? Well, there's 2 chlorines within the original complex ion. We'd name it first because we named ligands alphabetically, so it'd be dichloro, since it's the same identical and there's 2 of them. And then here, ethylenediamine has di in its name, and there's 2 of them in the formula. So this would be bis, and in parenthesis, the ligand name, bisethylenediamine. So this is how we name the ligand within this particular complex ion.
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concept
Complex Ion Naming
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And continue our discussion of naming complex ions and eventually coordination complexes. We are now ready to name the complex ion by adding the name of the transition metal. So here we have our transition metals, and we have their metal names, which are pretty standard for some, but then we have Latin based elements in the periodic table, so they're gonna have a Latin name. So here, if we're looking at just the regular way we name them, chromium, cobalt, manganese, molybdenum, you can see that the common theme is at the ending ends with 8. But then when we get to the ones with Latin based names, so iron here, it's simple as Fe based on its Latin name. So here would be ferrate, Copper, cu, this would be cuprate. Silver here is argentate. Tin here, s n, this would be stannate. Gold here, AU, that would be all rate. And then finally, we have lead, which is, PB, which would be plumbate. So these are some commonly referenced transition metals when it comes to naming these complex ions. On one side, we have their regular metal names, but then for the Latin based ones, they have new Latin names.
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example
Naming Coordination Compounds Example
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In this example, it says write the full name of the complex ion. So step 1, we've done before in earlier videos. It says name ligands in alphabetical order. So we have chloro here, and then we have ethylenediamine here. We'd say there's 2 chloros, so dichloro. Then we'd say that there are 2, ethylenediamines. Because of the presence of di, the numerical prefix, we'd use bis, bis and then ethylenediamine. Step 2, we name the transition metal after the ligands, and you remove spaces from all names. So we'll fix that up once we write the whole name out. So here, if a complex ion is a cation, which it's not, it has negative charge, the metal's name is not modified. If the complex ion is an anion, like it is in this case, then you change the ending of the transition metal to 8. Now this is important. Note, some transition metals will use Latin names. Now here you add a Roman numeral for oxidation number in parentheses after the metal name, and then you have to get and then the overall charge of the complex ion is not named. Alright. So let's put all of this together. We say that let's see. Our complex ion is negatively charged, so we have to change the ending of the metal, the transition metal to 8. Silver has a Latin based name. Its name would be argentate. That's the name of our metal. So now we'd also have to talk about what is its oxidation number. Well, here, this is neutral, so it's 0. Silver here is x. Chloride ions, each one is minus 1. So x plus the 2 Ethylene diamines, which are 0, plus the 2 Chloride ions, which each one is minus 1, equals the overall charge of the species, which is minus 1. So we're gonna have x minus 2 equals minus 1, x equals oops, x equals plus 1. So here this would be our silver one ion. So here, if we put it all together, we'd have dichlorobisethylene diamine, argentate, and then the roman numeral one. Again, remove all spaces from the name. So that's why it's all this one long string of letters and then our Roman numeral at the end. So this will be the name of this particular complex ion.
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Problem
Problem
Provide name of complex ion [Fe(CN)5NO]3–
A
pentacyanidenitrosylferrate(II)
B
pentacyanidenitroferrate(III)
C
pentacyanonitrosylferrate(II)
D
pentacyanonitroferrate(III)
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concept
Coordination Compound Naming
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At this point, we know how to name the ligands within our complex ion and the complex ion itself. Now we have to go one step further and talk about the coordination complex as a whole. So here we're gonna say similar to naming ionic compounds, we're gonna say that the name of the cation here, which is positive, is written before the anion, which is negative. And we're gonna say here that the cation can be either a counter ion or it could be a complex ion, so we have to pay very close attention. If we take a look here at these 2 coordination complex examples, here we have potassium connected to what's in the brackets. Remember, what's in the brackets is a clear giveaway that that is our complex ion, which would mean that what's in the red, this the potassium would be our counter ion. Okay. So here, this is our complex ion, and then potassium here would be our counterion. For the other one, it's reversed. What's in brackets is first, that is our complex ion, and it's the chloride ion that's on the end that is our counter ion. So just remember, the art in terms of naming the coordination complex as a whole is to be able to identify which portion is the counter ion and which portion is the complex ion. In addition to this, also recognizing which one is the cation and anion is essential to properly naming these coordination complexes.
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example
Naming Coordination Compounds Example
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Provide a systematic name for the following coordination complex. In it, what we have is our complex ion in brackets here, and then we have our counter ion in the form of bromide ions. Portions of this we've covered before. Step 1, we have to name the ligands in alphabetical order. If the ligand is negatively charged, we change the ending to oxo. If the ligand is neutral, you keep its name. Now remember we use numerical prefixes of di, tri, and tetra unless we're dealing with the ligand like ethylenediamine, where it has a numerical prefix in its name, so then we use the prefixes of bis, tris, and petrochis. Step 2, you name the transition metals after your ligands, remove the spaces between the names. If the complex ion is a cation, the metal name stays the same. If the complex sign is an anion, you change the ending to 8. Remember, some transition metals have Latin based names. We add a Roman numeral depending on the charge of the transition metal, and then the overall charge of the complex ion is not important in terms of naming it. Well, we don't include it in a name. It does help us to determine the charge of the transition metal, though. Now here, this is where it's new. We're talking about the counterion finally. Now if the counterion if it's a cation, the name is not changed. If it's an anion, you change the ending to ide. Polyatomic ions, their name is not changed. Finally, you write the full name of the coordination complex. You name the cation first before you name the anion, and then you add a space between the cation name and the anion name. So that's where a space is allowed. So if you move up back up here and take a look at this alright. So what do we have here? Well, we have here bromide ion, and then we have our complex ion, the 2 that's with the b r on the outside here, it came from this complex ion. So the complex ion portion is chromium with 5 waters, 1 bromide ligand, and an overall charge of 2 plus. Alright. So now let's name the ligands that are inside the complex ion. Water here, it's aqua, and then bromine here is bromo. We name them alphabetically. Here we have 5 waters, so that'd be penta for its numerical prefix name, so pentaaqua. And here you can drop the a because that'd be penta and aqua. You could drop one of the a's because that'd be 2 a's. So pentaqua, and then where there's only 1 bromo, so bromo. Now chromium here, we're gonna say if the complex ion is a cation, then the metal name is not modified. So we're looking at this portion here. So chromium is part of a positive complex ion, so it keeps its name. It's gonna still stay chromium, but we need to determine its charge. Well, here we don't know its charge, it's x. Water here is neutral, so it's 0. Bromine here is minus 1. We're gonna say x+5water, each one is 0, plus 1 times negative one equals plus 2. X minus 1 equals plus 2, x equals plus 3. So this is chromium 3 ion. We've named our complex ion portion. Then remember, if the counter ion is an anion, you change its ending to ide. So this would state the bromide ion. Remember, there's a space between the the cation portion, which is this complex ion, and the anion portion, which is this counter ion. So that would be the full name, pentaquabromochromium 3 bromide.
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Problem
Problem
Provide a systematic name for K2[Mo(O)Cl4].
A
Potassium tetrachlorocarbonylmolybdate(VI)
B
Dipotassium tetrachlorocarbonylmolybdate(IV)
C
Potassium tetrachloroxomolybdate(IV)
D
Dipotassium tetrachloroxomolybdate(VI)
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Problem
Problem
Provide name for the following coordination compound: [Ag(H2O)2]NO3.
A
Diaquasilver(I) nitrate
B
Dihydroxidesilver(I) nitrate
C
Diaquasilver(II) nitrosyl
D
Dihydroxidesilver(II) nitrosyl
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Problem
Problem
What is the systematic name of [Co(en)2(NH3)CN]Cl2.