 I once again welcome you all to MSP lecture series on interpretative spectroscopy. So since last couple of lectures I started discussing on NMR active nuclei other than 1H and 13C and in the previous one I showed you very nicely, very meticulously we can assign and interpret the spectra even if you do not know which nuclei it represents. But one thing is we should have vital information and we should analyze in a proper way and let we continue with more such examples and this is going to be my last lecture as far as NMR is concerned and then I shall move on to UV visible spectroscopy and then IR and at the end mass spectrometry as I have mentioned I will come back again at the end to discuss problems related to all these spectroscopic methods. I come up with more examples of again multi-nuclear NMR at the end of this lecture series. So now let us look into 1H NMR spectrum of borohydride. So that means we all know that NABH4 where B is in a tetrahedral environment with four hydrogen atoms and it is anionic and I have shown here 1H NMR spectrum of boron hydride. The element boron if you consider and if you look into the table I provided in my second or third lecture about all NMR active nuclei and their gyrominodic ratio natural abundance and also the corresponding sensitivity and details and nuclear spin. So now if you consider boron it has two isotopes and both are NMR active and 10 boron abundance is about 20% and its nuclear spin is 3 whereas 11 boron is 80% abundance and its spin is 3 by 2. So now let us look into this spectrum and rationalize the appearance of the observed 1H NMR spectrum. So now if you look into first one here we are seeing four lines of equal intensity and also we are also seeing some smaller lines here. So seven lines are there here. So let us try to see what it is and if you look into boron 10 boron I equals 3 and if you simply use this 2 Ni plus 1 rule here and 2 is 1, 1 nuclei is there and then let us put now 3 by 2 and plus 1 that means I am considering 11 boron here then we should get four lines here. So that means we are getting four lines in case of 1H NMR that means 1H is coupled with boron, 11 boron with I equals 3 by 2 and it is showing four lines of equal intensity that means immediately we can say this is due to 1J, B, 11 and H coupling and coupling constant is in the order of 50 hertz and now what is this seven lines here? Now let us look into 10 boron, in 10 boron we have again one boron is there and 3 plus 1 that means seven lines should be there and then here this is 80% and this is only 20% it is one fourth of the intensity so it should give seven lines of equal intensity. So we are seeing here this one and here that means basically this spacing is for 10 boron to hydrogen coupling and then this spacing is 11 boron to hydrogen coupling so that both are appearing here because both of them have appreciable abundance 80% and 20% that means 1H NMR of boron hydride consists of coupling due to both 10 boron which appears as seven lines and 11 boron which appears as quadrate of 1 is to 1 is to 1 is to 1 intensity. This is how the 1H NMR spectrum of boron hydride looks like. Let us look into 11 boron NMR spectrum of BH4 minus now if you consider 11 boron NMR you should remember the fact that boron is in tetrahedral environment with four equivalent hydrogen atoms as a result boron signal should be split into a quintet that is what we see here we have quintet it is because of boron coupling with four equivalent hydrogen atoms this is here 11 boron to hydrogen coupling is 64.9 Hertz and this spectrum can be obtained when we run 11 boron NMR so when we run 10 boron NMR spectrum how it is going to look like yes it is it looks more or less identical except for the separation the couplings would vary and 10 boron NMR also shows a quintet of this intensity ratio of these five lines and here 10 boron to hydrogen coupling is 27.3 Hertz and both look identical by just looking into the spacings or couplings we should be able to distinguish between 11 boron NMR spectrum and 10 boron NMR spectrum. Now let us look into 11 boron NMR spectrum of BF3 dietherate diethyl ether of course you should know that BF3 is very reactive and we cannot store it without forming an adduct it is unstable and then if you add BF3 to a donor solvent such as ether or SME2 it readily forms a adduct and that can be in solution and handling would also be easy so most of the time we get whether BH3 will come as SME2 and BF3 will coming as etherate handling would be very easy it comes in known molar concentration and then if you look into 11 boron NMR spectrum you anticipate boron to fluorine coupling and then 11 boron NMR should be consists of a quadrate of 1 is to 3 is to 3 is to 1 intensity but how it is going to look like so it looks like a singlet that means coupling to proton or fluorine is not usually observed except in the smallest and most symmetric molecules such as BH4 minus only in case of BH4 minus you can see coupling where in most of the other boron compounds whether you have fluorine on it whether you have hydrogen on it normally you do not see coupling and same thing is true if you run 19 FNMR 19 FNMR show a probably a singlet does not show any coupling with boron rarely we come across those things we have examined numerous examples of compounds having BF2 with both 11 boron NMR as well as 19 FNMR both of them would show only singlets so then 10 boron NMR has a lower sensitivity and results in broader signals than 11 boron so it is always ideal to use 11 boron NMR unless the sample is enriched with 10 boron due to the you know lower sensitivity of 10 boron if you want to interpret data or we want to look into boron NMR it is always better to look for 11 boron NMR rather than going for 10 boron NMR unless the sample is enriched with 10 boron so now let us look into another interesting NMR active nucleus that is mercury and mercury has 2 NMR active nuclei 199 mercury and 201 mercury and 199 is about 16.84 percent abundant and it is I equals half and then if we look into 400 MHz NMR the corresponding frequency for mercury 71.3 MHz and the other one is 201 mercury that is 13.2 percent abundant and I equals 3 by 2. 199 mercury is a low sensitivity nucleus and its sharp signals for a wide chemical shift range whereas 201 mercury a quadcopolar low sensitivity nucleus that is broad signals and 199 mercury NMR used for the study of mercury compounds their structure dynamics and conformation it is also used for biological bindings studies using its relaxation effects once again whether we are looking into 199 mercury or 201 mercury the standard use it is dimethyl mercury so dimethyl mercury is set as 0 and then the chemical shift range can be 1000 to minus 3000 for mercury iodide comes around minus 3000 and mercury nitro compound comes between minus 2000 to minus 3000 and dibromo mercury shows around minus 2000 and between minus 1000 to minus 2000 mercury chloride shows and of course here you can see the argonomercury compounds and argonomercury compounds come in this the range that is shown here let us look into some examples of compounds containing mercury so one such example is dimethyl mercury and if you look into 199 HG NMR here you can see 6 hydrogen atoms are there so CH3 CH3 so here 6 hydrogen atoms are equally coupled to mercury and as a result what we are getting is a separate here so with coupling 199 mercury to hydrogen coupling of 100.9 hertz here and then when we look into 1 H NMR spectrum of dimethyl mercury we get one signal here this is for NMR inactive and then since we have a small percentage of 199 mercury is there it will also show a satellite peak here and this here the mercury hydrogen coupling is 109 hertz this should be same as this one here so that means 1 H NMR spectrum consists of a singlet with mercury coupling satellites with a mercury hydrogen coupling of 109 hertz whereas 199 mercury NMR consists of 7 lines the septic because of coupling with hydrogen atom so now let us look into 13C NMR of dimethyl mercury and again here you can expect one signal broad signal and then having mercury satellites and here 1J mercury 199 mercury to 13C coupling is about 686.2 hertz now we have another interesting molecule is there and we have dialkyl mercury a compound is there alkenyl so we have here three different type of fluorine atoms are there on each one you can distinguish these two are identical in the red and then we have in the green they are identical and then these two are identical that means they are equally coupling to mercury so that means first these two bond apart fluorine atoms will split mercury into triplet so this one is 2J mercury fluorine coupling now we will come to this one this will be split into triplet again so I have given in the color here so this is if you see 1 2 3 bond coupling mercury to coupling now we have these blue ones they are also 1 2 3 coupling so they are further splitting this into triplet here so if you see here this can be called as triplet of triplets of triplets if you want to spell out this how you should say whatever the splitting pattern you have to start from the beginning that should come first because triplet of triplets of triplets this is how you should pronounce the spectrum and this how it is going to look like and of course you can also distinguish here the various couplings so this is a very interesting structure here NMR spectrum here for mercury so triplet of triplets of triplets let us look into one more interesting spectrum here look into here one of the fluorine is replaced by CF3 group so that means basically to begin with very similar to what we had earlier these two would couple together to give a triplet and then next these two would couple to give split this triplet into triplets and now the CF3 group we have 6 of them are there 6 equivalents are there so 6 equivalents means if you again you go with the 2 Ni plus 1 rule 2 7 that means each of this triplet lines will be further split into 7 lines so something like this all of them so that means this one we can call it as triplet of triplets of separates so this how the spectrum looks like this is a triplet of triplets of separates I think that is enough here about mercury NMR and in case if you have some examples where interpretation is a problem you can always show it to me so that I can interpret and give the information back to you so let us look into one more example here trifluoro phenyl substituted boron here and this is a 19 F NMR spectrum what I have shown here and if you look into 19 F 4 NMR spectrum and by just looking into that one you can conclude that these two are equivalent ortho fluid atoms are equivalent and then we have metafluid atoms are another set and then we have another set in 1 is to 2 is to 2 ratio that means we can see 3 different type of fluid atoms are there and you can see here and of course they can also couple with boron or hydrogen as a result they show the multiplied and I do not have a resolved spectrum here but nevertheless by looking into those things you should be able to identify 3 different type of fluid environments in this molecule so now let us look into one more example this is about lead lead also have several naturally occurring isotopes including 204 PB 1.5 percent natural abundance and 206 PB 24 percent abundance and also we have 207 PB 22 percent abundance and also we have 208 PB 52 percent abundance of these isotopes only 207 has non-zero nuclear spin of I equals half 207 207 is 22 percent I equals half this is NMR active that means if you have any lead compound like tetra methyl lead or tetraethyl lead is there certainly we can run 207 lead NMR to know its chemical shift environment and what would you expect to observe for the 1 H NMR spectrum of tetra methyl lead given that 2 J PB H coupling is 60 hertz that means the value is given PB H and if you just look into tetra methyl lead so what the data provided is this 2 bond coupling 2 bond coupling 60 hertz that means how the NMR spectrum would look like in case of tetra methyl lead 1 H NMR spectrum so let us draw and you should remember the fact that 207 PB abundance is only 22 percent so if it is 22 percent then the 78 percent is you should consider I equals zero non NMR active lead so that would show a singlet something like this that means out of 100 molecules of tetra methyl lead about 78 molecules do not have NMR active lead as a result that would appear as a singlet here but whereas 22 percent of 207 would split hydrogen signal into a doublet something like this here and then this would be 11 percent and this would be 11 percent and this is 78 percent and then this coupling will be 60 hertz this is what the information is given this how the spectrum would look like 1 H NMR spectrum of tetra methyl lead so this is all about lead NMR and of course today I discussed about 10 boron 11 boron NMR and 199 mercury NMR and also how boron interaction would take place in sodium borohydrate to give a quartet for 11 boron coupling and also separate for of same intensity for 10 boron with I equals 3 and 11 boron I equals 3 by 2 in case of boron components you should remember if the molecule is not symmetric probably we do not see boron fluorine coupling or boron hydrogen coupling whereas in case of symmetric molecules such as BH4 which are very nicely splitting of boron by hydrogen as well as hydrogen by boron and also we could see in 1 H NMR spectrum of boron hydrate coupling of both 11 boron and also 10 boron so with this let me stop here and continue in my next lecture about a new spectroscopy topic that is UV visible spectroscopy until then have an excellent time reading interpretive spectroscopy. Thank you.