 If you have understood octahedral you know octahedral splitting, you should be able to understand tetrahedral. But of course, the problem being it is tetrahedral the angles are different. Octahedral good thing it was on d z square you have one orbital clearly and the ligands are coming from there d x y x and y direction ligands are coming directly. In tetrahedral you see the orbitals in somewhere the ligands are coming from somewhere it is not like head on collision, it is not exactly direct approach of the ligand I mean direct overlap of the ligand and orbital are not happening. That is where of course, you should be able to understand the destabilization will not be that much. So, the splitting of course, there will be splitting also in the d orbital splitting extend to which the splitting will occur will not be too much, because in octahedral it is a head on collision. Then in tetrahedral it is going to be side on just touching and going almost kissing and running away right. So, that is where that is where you will see in tetrahedral you will never have any low spin configuration means the extend of separation between t and e or in this case we do not say t 2 g and e g we say t 2 and e ok same d x y d y z d x z it is t 2 e not e g e is d x 2 y 2 d z 2 ok will come. Since octahedral we are saying that of course, 6 of the ligands are approaching in tetrahedral only 4 of them are approaching. In octahedral it is a head on collision in tetrahedral it is you know just side wise you can say or very little collision very little good evaluator. The repulsion from the ligand or ligand electron will not be able to repeal the metal electron that efficiently as you see in the octahedral case. So, the splitting the repulsion is the splitting is nothing, but difference between e and t 2 whatever we were saying these 3 orbital versus 2 orbital splitting the distance. So, that is never going to be too high if it is not too high if it is always like this at let us say room temperature the electron can access all of them. So, it is always going to be high spin we do not have to worry about low spin in tetrahedral case only in octahedral case we have to think about low spin and high spin clear. The reason is very simple number of ligands are less. So, repulsion is less 4 versus 6 4 ligands versus 6 ligand tetrahedral means 4 ligands and also the approach of the ligand with respect to the orbital is not going to be direct it is almost a side approach ok. Now, so the ligands as you can see occupying alternate orbital over here alternate sorry occupy alternate corner 1 2 3 and 1 in the back 4 ligands right. You imagine just methane CH 4 how the hydrogens are with respect to carbon. Imagine carbon is your metal center and 4 hydrogens are your 4 ligand that is how it is right it is not octahedral it is tetrahedral. So, E orbitals we will be calling E orbitals and T 2 orbitals ok. So, here they are in this case actually I will say you why it will be in this case it is the reverse of octahedral these are going to be stabilized d g 2 and d x 2 y 2 are going to be stabilized because these orbitals are the ones which will be facing this ligand least. So, ligand is here ligand is there ligand is there and ligand is there can you see the 4 ligands 4 black dots strong dots 1 2 3 4 see the d z square orbital and d x 2 orbital y 2 orbital these 2 orbitals are facing the ligand least they are farthest from the ligand that means, the repulsion will be less or they are the one which is going to be stabilized. If you think about the octahedral of course, from the 3 metal ion everything destabilized and from there further stabilized and further destabilized right over here the pattern is just opposite 3 2 was for octahedral it will be 2 3 T 2 sorry E will be the stabilized one T 2 not T 2 g mind you not E g again E and T 2 these are coming from symmetry elements which will not be taught. So, it is like this. So, these 2 orbitals are stabilized these 3 are destabilized relatively destabilized see once again these are the 4 ligands 1 2 3 4 these 4 ligands are with respect to these it is more close to the orbitals these ligands are close to these orbitals more compared to these you just see look at the angle how far they are you will be able to see it ok. It is going to be little bit twisted from octahedral because octahedral it was clear cut tetrahedral you have to see that 109 angle 109 angle right that is the angle between the 2 you know 2 ligands going to be right. Now, these are the one these d orbitals are the one which is going to be destabilized compared to these 2 that is because they are facing the ligand more efficiently or their ligand electrons and metal electrons are going to repeal each other more strongly because they are coming too close to each other compared to that we see in here clear you see it should be fine. Now, also just numerically speaking you can see that the e orbitals are of course 109 angle total if you see the geometry and it is 2 of them. So, it is 54 degree with respect to the center you can look at if it is not clear you can come back I will just t 2 is nearer to the ligand hence higher energy e is further from ligand then thereby lesser energy I think this picture gives you the clear idea where the ligands are and where the orbitals are it is a 3D view no amount of explanation will not be good enough you have to look at I cannot explain perfectly you have to look at ok. Now, so if you look at delta G and delta T in delta 0 delta 0 it I meant actually delta octahedral delta T means delta tetrahedral this is the splitting ok. Now, this splitting delta 0 will be very high that is what we are saying compared to delta T what is the reason once again 4 ligand versus 6 ligands you have 6 ligands for octahedral you have 4 ligands for tetrahedral thereby the delta T will be less delta 0 or delta octahedral is always going to be more ok. Now, what is the extent and also you have seen e below T 2 up. Now, overall this is the one you have to kind of remember it is like 2 third and 2 third why 2 third and 2 third. So, 4 9 where is that coming from. So, 4 ligands versus 6 ligands 6 times 2 third is going to be 4 ligands 6 ligands was for octahedral 4 ligand is for tetrahedral. So, 2 third number of ligands 2 third times 6 is 4 there is a component of 2 third and there is this roughly due to the angle since they were colliding head on and here it is a 109 degree angle is there and thereby how the orbitals are oriented towards the ligand that gives you another 2 third means what I am saying is the extent to which ligand in octahedral case is interacting versus extent to which tetrahedral is interacting overall that is going to be 4 9 of delta 0. Delta octahedral is always going to be higher compared to delta tetrahedral for a let us say given metal complex. You have ML 4 ML 6 same metal same ligand everything else oxidation states same. So, tetrahedral that destabilization or the splitting is always going to be less how less it is 4 9 times delta 0 where the 4 9 is coming from 2 third times 2 third 2 third times 2 third 2 third due to the number of ligands 6 times 2 third is 4 another 2 third due to the angle of approach how it is coming ok. Anyway that is what I was trying to tell all tetrahedral complexes are high spin because the splitting is less understood octahedral and tetrahedral completely different scenario T 2 G lower E G up here E not E G ok E lower T 2 up that is all you need to know now let us go. So, as you see now you look at these values we were saying 20,000 25,000 so on for this delta delta octahedral delta tetrahedral is always very small in number. If you now go back and look at the corresponding let us say octahedral complex you will be able to see that these are lower in number 5 10 minutes 5 minutes. So, if you now compare the stability or overall between octahedral and tetrahedral if it is 0 electron no stability let us say we are not talking if it is 1 electron in the octahedral case the blue line is for octahedral ligand field stabilization energy plot versus number of electrons plot. So, if you have 1 electron it is going to be in T 2 G 1 for octahedral case it is going to be 0.4 if you have 2 unfair electron it is going to be 0.8 or 8 d Q or 0.8 delta 0 we are talking 4 d Q then 8 d Q if it is 3 it is 12 or 1.2 delta 0. Similarly, you can start putting for tetrahedral tetrahedral it is E 1 not T E 1 E 2 E 1 is going to be 6 6 delta T if that 6 delta T you multiply by 4 9 of delta 0 which that 4 9 term you will be able to see that this is the actual difference. This plot actually makes complete sense 5 unfair electron we are talking all high spin versus high spin octahedral high spin tetrahedral high spin we are comparing 5 unfair electron high spin in octahedral means T 2 G 3 E G 2 0 total 0 3 of them are in here 2 of them are in here. So, 0 in octahedral in tetrahedral it is always high spin E 2 T 2 3 right. So, it is once again going to be 0 that is how for as the number of electron increases how the high spin case ligand field stabilization energy is varying you will be able to understand. I think we are losing the concentration I am with you just 1 or 2 minutes I will not take too much. Now, so let us look at this one if you understand little bit of this one I think I will let you go today ok. Taking you pick up 3 3 unpaired electron number of electrons is 3 number of 3 unpaired electrons or 3 electrons d 3 configuration for octahedral case it is what T 2 G and E G it is going to be 1 2 3 T 2 G 3 and E G 0. T 2 G 3 means each of them are having 4 d Q stabilization. So, it is going to be minus 12 d Q or minus 1.2 delta 0 or delta octahedral that is the stabilization energy that is over there. Now, you talk about tetrahedral case 3 electron it is going to be E and T 2 E 2 T 2 1 E 2 T 2 1 E 2 means 6 plus 6 12 12 d Q stabilization. If it is 3 electrons 1 2 3 it is never going to pair up unless there is no option then it will pair up it is never high spin low spin situation it is always high spin situation 1 2 3 each of them are 6 delta T not delta O delta T. So, 2 of them are 12 delta T 1 of them is 4 delta T minus 12 plus 4 minus 8 minus 8 delta T. Now, that is tetrahedral how much it is in terms of octahedral multiplied by 4 9. So, apparent close to 4 4 delta O right yeah most of you got it. So, minus 6 times 2 plus 4 delta T that is going to be for E 2 T 2 1 this is going to be for tetrahedral E 2 T 2 1 electronic configuration overall how much it is? It is going to be minus 8 delta T. Now, as you know minus 8 delta T means minus 8 delta T means this is time 4 by 9 for overall this is going to be in delta 0 right. So, it is nearly going to be let us say 3.8 or 3.9 whatever it is 9 and 8 console out whatever it is 32 divided by 9 right. So, now, you look back in here 3.8 or so. So, that is how each of the electronic configuration once again mind you this is high spin tetrahedral is always high spin tetrahedral high spin versus octahedral high spin we are trying to compare you should be able to do this plot by yourself ok. If you think you have understood this class or if you after studying 10 minutes 15 minutes whatever it takes you or 1 hour whatever it takes you after studying it if you can plot this one I think that will reflect that you have understood the delta 0 and delta T business ok. Now, there is another term which is called octahedral site stabilization energy. What is that? That is nothing, but the same electronic configuration or same electron number if it is given for octahedral versus it is given for tetrahedral what is the stabilization net stabilization let us say net stabilization. This is 2 electron stabilization for octahedral this is 2 electron stabilization for tetrahedral what is the difference between the 2? You will never see that octahedral is less stable compared to tetrahedral it is always octahedral is more stable how much stable that is what is usually called octahedral site stabilization energy OSSE it is perhaps not discussed in the class. So, you can understand the difference for the same type of electron or same electronic configuration how much stability octahedral is going to get compared to tetrahedral ok, but mind you again this is the comparison between the high spin high spin tetrahedral high spin octahedral is always high spin octahedral high spin, but sometime this octahedral site stabilization energy can differ sometime tetrahedral is more stable if octahedral stabilized I mean octahedral that crystal field stabilization energy becomes less that can happen if it is let us say I mean scenarios will be there where you can have such thing we will discuss those ok. So, those next topic will be spinel normal spinel spinels are what spinels are nothing but the gems what you see these are different metal oxides with the form AB2O4 magnesium aluminum 1 magnesium 2 aluminum and 4 oxygen different of these you know the jewels that you see different rocks these are nothing but spinel. Spinels are of 2 types normal spinel and inverse spinel this is the only topic that is left for this chapter coordination complex. So, the class is over.