21.2 Naming Complex Ions and Coordination Compounds | General Chemistry

naming

complex

ions

and

coordination

compounds

will be the topic of this lesson. My name is Chad and welcome to Chad's Prep, where my goal is to take the stress out of learning science. Now, in addition to high school and college science preparation, we also offer datm cat. and oatmeal preparation too. I'll leave a link in the description below where you can find those courses now. This lesson is part of my new

general

chemistry

playlist that is almost finished, but for a couple more weeks I will continue to release several. lessons per week for the entire school year and I will start a new playlist shortly after, so if you would like to be notified every time I post a new lesson or start my next playlist, please subscribe to the channel, click the notification bell So we name

complex

ions

and

coordination

compounds

and we are going to divide them into cations and anions and technically we are going to name both cations and neutral complexes in a way, especially when you name the metallic part but with the anions.

We'll do it slightly differently for certain examples of certain metals, as we'll see, so we'll start with a complex cation here and try to make this as confusing as possible so that you know and in the formula Put the metal first into the ligand second, but in the name we put the ligands first and the metal at the end of that complex ion, so again, trying to make it confusing, that's my guess, so we'll name the ligands first and It turns out that you name the ligands, you name them in alphabetical order according to how they are named, so again water is not named as water, it is called aqua ammonia is not named as ammonia, it is named as amine and then it turns out that cl is chlorine and we I will name them in alphabetical order, so in this case the amine will go first am, then aqua aq and then chlorine c h after that, so it turns out that you're also going to use a numeric prefix to tell you, uh, to tell me exactly how many. there is so 2 is for die three for try four for tetra five for penta six for hexa if there is only one, although you will not use any prefix, don't do it, don't say monkey or anything like that, just leave the prefix off and so on for this first one here, so we have to start again by

naming

the amine first, we have three of them, so we're going to say: try amine, if you've had organic

chemistry

, you'll notice that there's a lot of nitrogen.

The compounds they contain are called amines with only one m, but here in coordination chemistry, as an amine ligand has two ms, just a word of wisdom, so triamine we have three amine ligands, and then water is next in line. the alphabet, so we have two of those, so it's going to be say aqua and then just chlorine, so we're just going to say chlorine, and then once you've named all those ligands, you finally named the metal and in this case. cr means chromium, so we're going to say chromium, a big long word, and then in parentheses you're going to put the oxidation state of that metal and you might have to figure that out based on what's in here, so Unfortunately, I will have to know the charges of your ligands, now I can see that this whole complex ion has an overall charge of plus two, but you are supposed to know that water and amine have no

general

charge, they are neutral and then chlorine is minus one and if there is only this ligand which is minus one, then we can deduce that chromium must be plus 3 if the overall complex ion is going to be plus 2.

So you have to put the Roman numeral 3 in there are parentheses there and this is the ion triamine diaquachlor chromium 3 and if you only have only the cation only the animal you are going to say ion in the end it is like if you have na plus, what would you call this? Would you just call it sodium? No, you would call it sodium ion at the end of the name, so if you have just one cation or just one anion, say ion at the end, okay, so for cations and neutral species this is how it says, what we're going to see is going to be a difference: when you name the metal for a complex anion you will always end up with a eaten ending, so if this overall had a negative charge for the entire complex, well then we would have said chromate, now notice, I'm saying it's a negative charge for the whole complex, the metal itself is always, you know, it can never have a negative oxidation, uh, negative oxidation state, it will be positive or, on certain occasions, rare.

In some cases it might be neutral, but it will always be positive, but the key is that if the whole complex has an overall negative charge like it does here, that's when we would end up with an ending in, we wouldn't have said chromium, we would have said chromate and To make this even more complicated again, it turns out that for select metals you will also use the Latin root with the ending ate, so if you notice we get quite a few transition metals that the symbol does not correspond to. to the English name like iron fe, why does it match? so fe comes from the Latin fair and when you have a complex anion with iron you don't say ironate, you say ferrate, so there are certain ones that you should know and I've put they are on hand here, so we have uh uh fe is uh ferry cu note that copper is co but cu is the symbol and that is cupra and then it would be cuprato, so ag argentate if you have spoken some French, you will be able to You will know that the big ant is money or silver, you know it, then you have a u would be orate for gold we're going to use here and then pb plum bait uh definitely lead doesn't start with a pb on the right and then sn for stan, which is uh tin, so we would say stan eight and again this only applies to complex anions so if I have a complex cation and gold is part of it I'm just going to say gold if you know irons are part of it I'm just going to say iron so it's just for complex anions that I use these Latin roots with an ending ate, so in this case we're going to name the ligands first once again, so we have four chlorine ligands and four are tetra, so we're going to say tetrachloro and then instead of gold here because it has a negative charge, yeah would have had a positive neutral charge, we would have just said gold, but again because it has an overall negative charge in this complex anion we will use orate a-u-r-a-t-e and then again the Roman numeral in parentheses and chlorine minus one, so gold in general must be plus four if the entire complex ion has its own overall negative charge two, so we'll put the Roman numeral four in here, so let's do it right, not four, how did I get that?

How about two plus two, so plus two and negative four here for a total of negative two and this is the tetrachlororate ion two. Okay, so we have another one. Something to deal with here and that's when you got polydentate ligands like we do here in this case so unfortunately you have to know their names so name this thing so en is short for ethylenediamine like ophen would be the Abbreviation of phenanthraline. and again, these are on that big list of ligands that are part of the study guide here, so oxalate would just be an ox in parentheses and diethylenetriamine would be a d-i-e-n in parentheses and things like that, so you need to know this.

Unfortunately, names because when you go to name them, the full name is part of the name, where it's just some little abbreviations that are part of the formula, so we're going to name all of our polydentate ligands in this case first or just ligands and it's ethylenediamine and there's three of them, well, it turns out that with polydentate ligands you don't use the ditri tetra, you're going to use bis tris and tetrakis, strange as it may seem, and since there are three, we'll say tris don't try it, so remember that's for the polydentate liggins have slightly different numerical prefixes, so this is tris ethylenediamine and notice that the diamine here only has one m, not two, as part of this big word ethylenediamine, oddly enough, and then we're going to name the metal and notice that we have a complex cation we're not going to say ferrate here we're just going to say iron and then we have to put a Roman numeral in parentheses once again and in this case you're supposed to know not only that ethylene is ethylene bidente Diamine is biodentate but it is also neutral, it has no overall charge, so in this case the iron must be responsible for the entire charge plus two, hence the Roman numeral two and we are dealing with just an ion, not a complete compound , so this is tris ethylenediamine iron two ions okay, now we're going to do a couple of examples of full coordination compounds where we have cations and anions, and it will work like we name other ionic compounds: first name the cation and then the anion so, and if they're simple, great and if they're complex, well, now we've learned some new rules for naming them as complex ions and stuff, but we're going to have to put them together, so if we know, also, that's the sodium ion if we have cl minus that is the chloride ion, but if we have nacl, it is now sodium chloride, a complete ionic compound and that is where we are heading with this with complete coordination compounds where we have both caron and anion and at least one of them will be complex in this chapter, but in the last example we will see where we have both the complex cation and a complex anion.

Let's take a look, so just a second ago we called this beautiful complex catym and it was the triamine ion diaqua chlorochrome 3 since chromium was in the plus 3 oxidation state and now we're going to make this cation also part of a compound full ionic, so in this case we're going to get rid of that plus 2 charge and just put a couple of chloride counterions in here, general neutral ionic compound, every once in a while when you name an ionic compound, you're still going to start with the cation first and second, so we'll name the cation first, but since it's not just a cation on its own, we'll take that ion out and once you've said the full cation, you'll just name the anion.

In this case, it's just a simple anion and we'll just say chloride. It's not dichloride or anything like that. Note that if we have nacl versus mgcl2, this is sodium chloride, this is magnesium chloride, so how many chlorides are there is implied by knowing the charges of the cations and knowing the charge of the chloride, so we don't say dichloride. or something like that for a simple anion, here it's just plain old chloride, although there are two of them and just a minute ago we also called this beautiful complex anion as tetrachlororate ii ion, but again, instead of having it as a standalone anna here. we're going to make it part of a coordination compound here, so we have both the cation and the anion, now a neutral compound and in this case we don't put ion on the end, so this is the name of the anion, but again without compounds, we name cation first, anion, second, so this will go at the end of the name, so we just have to say the name of the cation, well, this is just plain old sodium, just like we had it, you know, this has been sodium chloride . well this is just sodium tetrachloroate ii two great words and again the fact that there are two totally irrelevant sodiums so if we had na2 this would just be sodium sulfide and notice the two don't become part of the name just It is implicit in ionic compounds. based on you knowing the charges of cations and anions, how many will be in that balanced formula for a neutral compound.

Well, in this last example, instead of giving you the formula and asking for the name, now we will give you the name and ask for the formula and what will make this a little challenging is that both the catyan and the anion are complex ions, But as you'll discover, going from name to formula is actually a little easier. at least for a single complex ion, putting the two together is going to be a little difficult, so hexaamine nickel 2 nickels the metal ion well, so it goes first in the formula hexaamine means there are six ammonias here and then it's nickel two and nickel two. that means it will generally have a charge plus two since ammonia is neutral and nickels plus two are fine so here we have hexacyanoferates and ferry which is iron so we'll start with fe and then hexacyano which means there are six ligands and those are minus one each, you'll notice that all the negative uh ligands and all the organs that have a negative charge will always end with the letter o like cyano chloro fluoro, carbonado oxalate, etc., so it's a nice and convenient way to remind you .

Know and notice that water and amine do not end with an o and are not negatively charged, but this is hexacyanoferate two and in this case the cyanoligans are minus one each, so the iron here is plus two, so in Generally this should have a minus four. charge and so, just like you have simple cations and simple anons, you have to adjust the number of cations and anions to get an overall neutral compound, so if this is plus two and this is minus four, we don't have a neutral compound. until we put two big fat ones in there and now we have a neutral compound, so it's the same as if you had something like nas again, if you want to get the proper formula for sodium sulfide, you have to realize that sodium plus one sulfides minus two, these are not going to balance, you have to until you put the two right there so that the cations and anions balance perfectly in a neutral compound, so it's the same type of thing we did here, we had to figure out the chargegeneral of the cation general charge of the complex anion and then balance the formula by putting a subscript 2 here, but here is the general formula for this beautiful coordination compound now, if this lesson on how to name complex ions was useful to you, then a like and a comment letting me know are the best things you can do to support the channel now, in the next lesson we will start looking at isomers and it will require your best mental concentration, so if you need to grab some coffee before joining me in the next lesson , I recommend that you do it happily by studying.