Other Spin-Vi Nuclei

The signal intensity of an MR-visible fluorinated compound is directly proportional to the number of fluorine spins present, similarly to other spin Vi nuclei. However, a number of processes can restrict compound MR visibility and thereby impede quantification from... 

Since phosphorus and protons are both abundant spin-Vi nuclei, it is simple to design an experiment in which we correlate protons and phosphorus rather than protons with themselves. The result of this experiment, a P,H correlation, is shown in Fig. 26. Again we have the 2D spectrum in the form of a central rectangle and two (previously recorded) ID spectra parallel to the axes. One is the proton spectrum, the other the phosphorus spectrum. The latter of course consists of a single line, and in the 2D spectrum we do not need to look for a diagonal as there cannot be one. 

Proton signals will also be split by (J coupled to) other NMR-active nuclei that are nearby in the bonding network. Two commonly encountered spin- /2 nuclei are 19F and 31P (both 100% abundance). Common NMR-active nuclei that must be introduced by isotopic labeling include deuterium (2H, spin 1), and 13C and 15N (both spin Vi). 

The only sulfur isotope with a nuclear spin is which is quadrupolar (/ = 3/2) and of low natural abundance (0.76%). In view of these inherent difficulties and the low symmetry around the sulfur nuclei in most S-N compounds, S NMR spectroscopy has found very limited application in S-N chemistry. However, it is likely that reasonably narrow resonances could be obtained for sulfur in a tetrahedral environment, e.g. [S(N Bu)4], cf. [S04] . On the other hand both selenium and tellurium have isotopes with I = Vi with significant natural abundances ( Se, 7.6% and Te, 7.0%). Consequently, NMR studies using these nuclei can provide useful information for Se-N and Te-N systems. 

The proton nuclei have spins m = Vi, indicated as + and or as t and j.. The occurrence of the different proton spins of CH2 are (H)/ (Tl and equivalent, ) and (H). The three protons of the CH3 group feel the different magnetic fields of these proton spins and the PNMR spectrum exhibits a CH3 peak which is composed of three peaks with relative intensities 1 2 1. On the other hand the occurrence of the different proton spins of CH3 are (TTT)/ (Hi/ Tit/ and ITT)/ (Hi/ Hi and j T) and (HI)- The two protons of the CH2 group feel the different magnetic fields of these proton spins and the PNMR spectrum exhibits a CH2 peak which is composed of four peaks with relative intensities 1 3 3 1. 

Nuclear magnetic resonance (NMR) is a phenomenon that occurs when the nuclei of certain atoms are immersed in a static magnetic field and exposed to a second oscillating magnetic field. Some nuclei experience this phenomenon, and others do not, depending on whether they possess a property called, spin . Spin is a fundamental property of nature like electrical charge or mass. Spin comes in multiples of 1/2 and can be + or -. Protons, electrons, and neutrons possess spin. Individual unpaired electrons, protons, and neutrons each possess a spin of Vi. 

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