Coordination Compounds

Jules Bruno
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Hey, guys, In this new video, we're gonna take a look at coordination compounds. Now we're gonna say here the most important or most prevalent aspect of transition metal chemistry is the interesting types of compounds they form. We refer to these compounds as coordination compounds or coordination complexes, and important things to know about them is that these coordination complexes or compounds they are usually colored, so they form very vibrant colors reds, greens, blues, purples, different types of colors because of the transition metal involved also, so they're usually colored and para magnetic. So the transition metal that's in the center of them usually has at least one electron, that is UNP aired. Now we're gonna say here within a coordination complex here, this is our coordination complex that we're talking about. It's made up of different things were going to say the coordination complex. Um, there is at least one thing that we call a complex ion, and we're gonna say complex ion is a species that is made up of a metal cat ion. So the transition metal in the middle that is connected to molecules that are neutral or it can also be connected to an ions negative ions. These neutral molecules that are connected to the metal or these negative ions that are connected to the metal are called Liggins. Now this is important to understand the metal can. Ion is gonna act as an electron pair except er, and we say it's acting as an electron pair. Except, er we're basically saying that it's acting as a Lewis acid and then here the Liggins, which could be neutral molecules such as ammonia or water. Or they could be negative ions such as chloride ion or fluoride ion. These Liggins they're acting as electron pair donors, so they have lone pairs on them that can donate electrons to the metal cat ion. Since they're acting as electron pair donors, they're acting as Louis Bases when you guys get to that section, if you haven't yet in terms of my videos about acid and base identification, realize that they're different types of acids and bases out there here. We're talking about Lewis acids and bases, and here we're talking about how they donate electron pairs. All right, so are complex ion when we're looking at this right here, this is our complex. Well, they start coordination complex or commit coordination on compound. It breaks up into a complex ion, and then also, in order to maintain the overall neutrality of the compound, we use counter ions. All right, so how do we look at this thing and figure out how it breaks up? Well, we're going to stay here First. Is we should calculate what is the oxidation number of nickel here? Here. We're gonna say that nickel is X ammonia has no charge because it's a neutral covalin compound. So it's oxidation number zero. Chlorine here is minus one. So it be X plus for ammonia, as each one is zero plus two chlorine. Each one is minus one equals zero. The charge of the compound this cancels out. So this is X minus two equals zero. So X equals plus two. So oh, should realize here's this thing breaks up into two ions. It breaks up into the nickel connected to the four ammonia us. We find out that the oxidation number of nickel is plus two. Ammonia is zero. So the overall charge of this thing is two. Plus, Then we have these two chlorine that are also involved. They break Frias Well, there's two of them, each one minus one. So we're starting out with our coordination complex on the left side of the era, it breaks up into two ions. This part here, this is our complex ion. And again you're complex. Ion is made up of basically two major things. It's made up of your metal. Can I on And then it's made up of your Liggins, Liggan or Liggins. Here are Liggins are ammonia, which are neutral. But there could have also been ammonia with bro mean there could be more than one type of Liggan attached to the transition metal in the middle. And then here the C L minus is here. There's two of them, so overall, this is minus two. So these negative negative to charge overall would cancel out this positive to charge overall. And that's why our coordination complex in the beginning was neutral. So since it's giving us a neutral compound when they're together, these represent our counter ions. So that's how we basically look at something and we break it down into its components. I know there's a lot involved here. This complex ion is made up of a bunch of things together not as simple as your basic Ionic compound, but it's still based on the principles of them. All right, so now, now that we've talked about the coordination complex and how it's made up of a complex ion and the counter ion, we have to talk about the coordination number involved. Now we're going to say the coordination number is the number of ligand atoms bonded to the central metal cat I'll and here, basically the number of ligand atoms that are usually attached to the central element. Usually 24 or six Liggins are attached to the central metal. These are the most common numbers there is, on rare occasion, very rare. Eight. But here we don't worry too much about that one. That one's way out there in terms of off the different types of coordination compounds we conform. So remember your coordination numbers. The number of Liggins attached to your metal cat ion. Now here we're going to say the coordination number is based on the size or charge off the metal cat ion, and it's also based on its electron configuration, because remember, these coordination complexes are para magnetic, so we have electrons that are not paired up the mawr unpaid electrons you have, the greater the chance of the number of bonds you conform because remember, forming bonds means you gain electrons, electrons that you can use to pair up with your unpaid electrons. And we're gonna say here we're gonna say that the most common coordination number is six. However, two and four also common six just happens to be the most likely number for a lot of these coordination complexes. So if we're talking about this, we have to talk about geometries. So we're gonna say the types of the geometries allowed are based on the coordination number of the central metal ion. So the first one is linear in terms of its geometry. This happens when we have a coordination number of too. So basically, we have our metal cat ion in the center, and it's connected to two Liggins thes Liggins could be, um, negative or they can be neutral. So good example here is we could have copper and it could be connected to maybe too bro means. And we should realize here is that when it comes to the complex ion, we draw brackets around it, so for the complex iron. We're always gonna put brackets around it. Now, Here, these next to both happened when we have four. Liggins connected, um, to the metal cat island. Okay, so four here could be either Tetra hydro or they could be, ah, square plane or planner. How do we determine which one's gonna dominate? Well, basically, we look at the metal cat ion, and if the metal can ion has on electron configuration that ends with D 10 for example, zinc zinc is are gone for us to three d 10. If it has a D 10 configuration, then it'll be Tetra Hydro. If it has a D eight configuration, for example, if we want to think of d A, we could think of nickel because nickel is are gone for us to three d eight. Then it'll be square plainer or planner. So good examples here. I could do zinc connected to four hydroxide. Overall charges minus two. And how am I coming up with the overall charge? Well, we know that zinc is a type one medal. It's always plus two, but we have four hydroxide ions. Each one is minus one. So if you think about it. You have plus, to hear you have minus four here. Really? Because there's each one is minus one. That's why the charge overall is minus two. And then he could just do nickel. But those four hydroxide as well, also minus two overall notice how again? I'm putting brackets around the complex ion because that's what you're supposed to do to write it correctly. And then octahedron is when you have six around here. So we could just do cobalt. We could use now a neutral licking if we want. So you have six of them. You could say, overall, this charges plus three. So again, these are the most common types of coordination numbers here. Eight is possible, but you're not gonna see it within your book. So don't worry too much about that. Um, six is the most common one. The Liggins can be either neutral or negatively charged. And as we go more and more until coordination complex will be taking a look at the different shapes, they can have the different types of ice tumors that exist as well as how do you name these different types of molecules? It's a bit different from the naming of normal ionic compounds and Covalin compounds, so it's gonna be a whole new set of rules that you have to remember. So just remember coordination complex looks at the complex on with its counter ion in the complex ion, we have our metal ion in the center connected toe Liggins, which can be either negative or neutral. The counter ion is just an ions that are used to balance out the overall charge of the complex ion that overall were neutral. Remember these principles when looking at coordination complexes?