25 MHz 13C NMR spectrum of diphenyl selenide in CDCl3.
Figure shows the fully coupled and decoupled 13C NMR spectra of diphenyl selenide. Although the large 1JC-H splittings are easy to identify, the fine structure of the individual multiplets is not first order (e.g., only the para carbon has an approximately centrosymmetric pattern, the others do not). This is because we are looking at the X part of an AA'BB'CXpattern (^JABC^j are protons, X is carbon). Since the AA' and BB' parts are strongly coupled, we see the usual complex effects of "virtual coupling" on the X resonance When noise {1H} decoupling is applied, the spectrum becomes much more intense, and only 4 lines remain, one for each carbon.
In this compound we have a second magnetically active nucleus (77Se, natural abundance 7.5%, I = 1/2), so each of the 13C peaks has 77Se satellites, although coupling between C-4 and the selenium is too small to detect (the satellites are under the main peak).
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