Naming Coordination Compounds - Online Tutor, Practice Problems & Exam Prep

• Ligands in coordination compounds can be anionic or neutral; anionic ligands typically end in 'o' (e.g., bromo, oxo, cyano), while neutral ligands are named directly after their common names (e.g., aqua for H2O, amine for NH3).
• Transition metals in complex ions are named using their standard names or Latin-based names, with endings like 'ate' (e.g., ferrate for iron, cuprate for copper).
• The naming of a coordination complex involves identifying and naming the cation and anion, with the cation written first. The complex ion is usually enclosed in brackets.
• In coordination complexes, it's crucial to distinguish between the counter ion and the complex ion, as well as to correctly identify which is the cation and which is the anion for proper naming.

Ligand Naming

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 going to 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 going to 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 amniotic or negatively charged ligand side, so for example here bromide ion, its ligand name is bromo oxide is O2-. In terms of its ligand name, it's Oxo. Hydroxide becomes hydroxyl, 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 N3-, 1. Here it would be called izodo and then Nitro is nitrate, Nitrate is Nitro, oxalate anion is oxalado 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 login. Aqua is water, so H2O MEME is the ammonia molecule, Carbonyl is Co carbon monoxide. We have nitrosol, which is NO, and then finally we have ethylene diamine. 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. Ethylenediamine is just EN for short, so these are the most important and most commonly used negatively charged ligands and neutral ones.

Naming Coordination Compounds Example

In this example question it says write names of all ligands and complex ions. So here we have a silver connected to two of these ethylene diamine or bidentate ligands. Then we have two chloride ions right? So step one 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 login here it would be the chloride ion. So here if we're saying chloride is this CL^-, then its name would become Chloro. Next, if a ligand is neutral, name is. Molecules, with exceptions here are neutral ligand would be this. Basically this ethylene diamine the en. 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 Ethylene Diamine as its name.

And then when more than one identical login, we use the prefixes of die for two, try for three, Tetra for four. Usually we'll 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 ethylene diamine di here is a numerical prefix, then you place the ligand in parentheses and use the prefixes of this if there's two of them, Tris if there's three of them, and Tetra kiss if there's four.

OK, Again, we see this with ethylene diamine because it has the dye in its name that numerical prefix with also information. How would we name these two ligands? Well, there's two 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 then here ethylene diamine has dye in its name and there's two of them in the formula. So this would be bis and in parentheses the ligand name bisethylene diamine. So this is how we name the ligand within this particular complex ion.

Complex Ion Naming

In 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 going to have a Latin name.

So here if we're looking at just the regular way, we name them chromium, Cobalt, Manganese. You can see that the common theme is that the ending ends with eight. But then when we get to the ones with Latin based names, so iron here it's symbol as Fe based on its Latin name. So here would be ferrite copper CU. This would be cooperate Silver here is argentate tin here SN this would be Stan 8 gold here AU that would be alright. And then finally we have a lead which is PB, which would be Plumb bait.

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.

Naming Coordination Compounds Example

In this example it says write the full name of the complex ion. So step one we've done before. In earlier videos it says name ligands in alphabetical order. So we have chloro here and then we have ethylene diamine here. We'd say there's two chloro, so dichloro. Then we'd say that there are two dot ethylene diamines. Because of the presence of dye, the numerical prefix we'd use bis, bis and then ethylene diamine.

Step two. We name the transition metal after the logins, and you remove spaces from all names O We'll fix that U once we write the whole name out. O here if a complex ion is a cat ion, which it's not, it has a 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 important note. Some transition metals will use Latin names. Now, here you'd 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. All right, so let's put all of this together. We say that, let's see our complexion 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 -1, so X plus the two ethylenediamines which are 0, plus the two chloride ions, which each one is -1 equals the overall charge of the species, which is -1. So we're going to have

X + 0 + 2 ⁢ ( - 1 ) = - 1

X = + 1.

So here this would be our silver one ion. So here, if we put it all together, we'd have dichlorum bis ethylene diamine. And in 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.

Provide name of complex ion [Fe(CN)₅NO]^3–

• A. pentacyanidenitrosylferrate(II)
• B. pentacyanidenitroferrate(III)
• C. pentacyanonitrosylferrate(II)
• D. pentacyanonitroferrate(III)

Coordination Compound Naming

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 going to say, similar to naming ionic compounds, we're going to say that the name of the cation here, which is positive, is written before the anion which is negative.

And we're going to 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 two coordination complex examples. Here we have potassium connected to what's in the brackets. Remember what's in the bracket 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.

OK, so here this is our complex ion and then potassium here would be our counter ion. 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.

Naming Coordination Compounds Example

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 one we have to name the logins 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 die, try and Tetra unless we're dealing with the ligand like ethylene diamine where it has a numerical prefix in its name. So then we use the prefixes of this Tris and tetricus.

Step 2. You name the transition metals after your ligands. Remove the spaces between the names. If the complex sign 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 without a Roman numeral depending on the charge of the transition metal and then the overall charge of the complex sign is not important. In terms of naming it, well we don't include it in the 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 counter ion finally. Now if the counter ion, if it's a cation, the name is not changed. If it's an anion, you change the ending to ID polyatomic ions. Their name is not changed. Finally, you write the full name of the coordination complex. You name the cat ion first before you name the anion, and then you add a space between the cat ion name and the anion name. So that's where space is allowed.

So if you move back up here and take a look at this, all right. So what do we have here? Well, we have here Bromide ion and then we have our complex ion, the two that's with the BR on the outside here it came from this complex ion. So the complex ion portion is chromium with five waters, one bromide ligand and an overall charge of two plus.

All right, 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 the penta for its numerical prefix name, so penta, Aqua. And here you can drop the A because that B penton and Aqua. You could drop one of the as because that would be two as, so penta, Aqua. And then there's only one bromo, so bromo.

Now chromium here we're going to say if the complex ion is a cat ion, then the metal name is not modified. So we're looking at this portion here. So Chromium is part of a positive complex science or keeps its name. It can 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 -1. We're going to say X + 5 water. Each one is 0 + 1 * -1 = + 2 X -1 = + 2 X = + 3 So this is Chromium 3 ion.

We've named our complex ion portion. And remember if the counter ion is an anion you change its ending to ID O. This would state the bromide ion. Remember there's a space between the the cat ion portion, which is this complex ion and the anion portion which is this counter ion. So that would be the full name. Penta Aqua bromo Chromium 3 bromide.

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)

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

What is the systematic name of [Co(en)₂(NH₃)CN]Cl₂.

• A. Amminocyanodiethylenediaminecobalt(II) chloride
• B. Amminecyanobisethylenediaminecobalt(II) chloride
• C. Amminocyanodi(ethylenediamine)cobalt(III) chloride
• D. Amminecyanobis(ethylenediamine)cobalt(III) chloride

Here’s what students ask on this topic:

When naming coordination compounds, are ligands always listed?

Yes, when naming coordination compounds, ligands are always listed as part of the compound's name. The ligands are named before the metal ion in the chemical name. If there are multiple ligands, they are listed alphabetically regardless of charge or the number of each type of ligand present. Neutral ligands are usually given their common names, with some exceptions (e.g. water is called 'aqua'). Anionic ligands typically end in '-o' (e.g. chloride becomes 'chlorido'). Prefixes like di-, tri-, tetra-, etc., are used to indicate the number of each type of ligand if there is more than one. These prefixes are not considered when determining the alphabetical order of ligands. After naming the ligands, the metal is named, and its oxidation state is indicated in Roman numerals in parentheses. If the compound is an anionic complex, the name of the metal ends with the suffix '-ate'.

How to name coordination compounds?

Naming coordination compounds involves a specific set of rules to ensure that the chemical composition and structure of the compound are clearly communicated. Here's a simplified summary of the process:

1. Name the ligands first: Ligands are the ions or molecules attached to the central metal atom or ion in the coordination compound. Name them in alphabetical order, regardless of charge. Use prefixes like 'di-', 'tri-', 'tetra-', etc., to indicate the number of each type of ligand. Anionic ligands typically end in '-o' (e.g. chloride becomes chlorido), neutral ligands are often named as the molecule (e.g. water becomes aqua), except for a few special cases like ammonia, which is named as ammine.
2. Name the central metal: After the ligands, the name of the central metal atom or ion is given. If the complex is an anion, the metal name ends in '-ate' (e.g. iron becomes ferrate). For transition metals, the oxidation state of the metal is indicated in Roman numerals in parentheses immediately following the metal name.
3. Add prefixes for the entire complex: If the complex is a cation or a neutral molecule, no further changes are needed after naming the metal with its oxidation state. However, if the complex is an anion, the name of the