Sketch the structure of the complex in each of the following compounds and give the full compound name:

a. cis-[Co(NH₃)₄(H₂O)₂] (NO₃)₂

Video transcript

All right, hello everyone. So this question says to draw the structure of the complex in the provided co ordination compound and give the complete name of the compound. And here we have cis conh 34 cl two cl. Now, in this particular case, the topic at hand is revolving around identifying and naming a metal complex in a metal complex. The central atom is generally a transition metal and that transition metal is bonded to a group of surrounding molecules or ions known generally as ligands. If the complex itself has an overall charge, then that's referred to as a complex ion compounds containing these complexes are known as co ordination compounds. But in this particular case, we're given the co-ordination compound overall. So the idea is to identify which portion of the compound contains a transition metal. And so here we can see that the portion in question is inside of the brackets, there is one transition metal here that's cobalt, which must be the central atom of the complex. And so now that we know what the central metal is going to be, let's go ahead and talk about how to draw our leggings in particular the way in which we draw our ligands connecting to the central metal atom depends entirely on the co ordination number of that particular ligand. Now, the co ordination number is the number of ligand atoms directly bound to the central metal. For example, a lien is considered to be mono dentate if it binds to the central metal via only one donor addict. In other words, only one bond is establishing, sorry, only one atom is establishing a bond to the central metal. Examples of mono dentate ligands include water chlorine and ammonia. That's an H three. And so based on this, we can see that all of our ligands that's four ammonia and two chlorine, all of these are mono dentate. So from here, let's talk about the charge of the complex as a whole because it is worth mentioning that outside of these brackets is one additional chlorine atom. Now, this chlorine atom is actually a chloride ion because it's inside or excuse me, outside of the brackets, it's going to be a counter ion. And so if chloride has a negative one charge, then the complex as a whole should have a positive charge. And so with this in mind, let's go ahead and start by drawing out our central Cobalt Yep. And so now we know for a fact that each of our ligands is going to connect to our central Cobalt atom via only one bond. However, notice that configuration has also been mentioned because this complex is supposed to be in the cis configuration, recall that a complex has or is in the SIS configuration if ligands of the same type are adjacent to each other around the central metal. So here to go ahead and showcase that CIS configuration on the right side, I'm going to draw both chlorine ligands adjacent to each other. This means that the remaining spaces are going to be for those NH three legates. And so from here, because this complex does have an overall charge, I'm going to enclose this in brackets and I am going to place the charge on the outside. So here I'm putting a positive one charge. So now just to clarify the co-ordination number of this particular complex, because all of these ligands are mono dentate, they each contribute a co-ordination number of one by dentate ligands coordinate or contribute a coordinating number of two and so on. So six mono dentate ligands means that the co-ordination number of this complex is equal to six. So now let's talk about naming. In this particular case, we have a complex cion followed by that counter anion. The cion is always written before the anion in the compound. So let's go ahead and tackle the name of our complex cion first. And so here recall also that all of the ligands present in the complex must be named in alphabetical order before the name of the central metal. The alphabetical order does not include prefixes. So let's go ahead and talk about that. As for ligands, we have four NH threes and two chlorine. Now, NH three is an example of a ligand that has a unique name to it, namely, it's described as amine with two MS where is chlorine is coral. However, because there are multiple copies of the same ligand present in this complex prefixes are necessary to specify how many there are. So two chlorine means the prefix is die. So die chloral and four NH three groups means that the appropriate prefix is tetra. So that's tetra ami. However, these prefixes are not going to be considered when deciding the alphabetical order. So here the A in a mean goes before the C in coral. So that's how we're going to write them. So from here, now that we've identified all of our ligands, the central metal is going to be named. However, because the central metal is a transition metal, it's important to specify the oxidation state in the actual name. So to go ahead and determine the transition, excuse me, the oxidation state of our transition metal, it's important to remember that the sum of all oxidation states and charges should equal the overall charge of the complex. So here the oxidation state of Cobalt added to the charges contributed by all Liggins should equal the overall charge, which is positive one. And so from here, recall that NH three is neutral and chlorine or rather chloride has a charge of negative one. So here I can make some substitutions, I can say that the oxidation state of Cobalt added to four multiplied by zero and added to two multiplied by negative one is equal to positive one. This means I can simplify my expression. And I can say that the oxidation state of Cobalt subtracted by two is equal to positive one. This means that the oxidation state of Cobalt in this complex is equal to positive three. So now lets go ahead and write out our name. But before I do that, let me actually move this information upwards. So first, as mentioned previously, we're going to go ahead and list our ligands in alphabetical order with no spaces in between them. So that's tetra amine die coo this is followed by the name of the transition metal which is cobalt. And then after the transition metals name is a Roman numeral for the oxidation state in parenthesis, that's Roman numeral three. And this is the name of the cion in the overall complex. And so because the configuration was also specified, this is in the cis configuration that should be included before the actual name of the complex with a dash in between them. So, so far, we have sis dash tetra amine chloral cobalt three. And then the counter ion which is chloride is written after the cion with a space in between and there you have it. So now we have our complex and our name is as follows, it is cys tetra amine di Chloro Cobalt three chloride. And with that being said, thank you so very much for watching. And I hope you found this helpful.