77Se NMR spectroscopy

The 77Se NMR spectra can be used to analyse the composition of a complex mixture of Se-N compounds. For example, 77Se NMR provides a convenient probe for analysing the decomposition of selenium(IV) diimides RN=Se=NR (e.g., R=tBu).30 An elegant application of 77Se NMR spectroscopy, in conjunction with 15N NMR spectroscopy, involved the detection of the thermally unstable eight-membered rings (RSeN)4.31... 

Terminal selenido complexes 181 and 182156 with a tetracoordinate germanium atom displayed downfield shifted signals in 77Se NMR spectroscopy (S 77Se = 1023.8 and 1115.6 ppm vs Me2Se, respectively) comparable to... 

C, and 77Se NMR spectroscopy. The compounds having either one or both of the selenium atoms substituted by sulfur showed irreversible oxidation by CV.141... 

Mugesh, G, A Panda, HB Singh and RJ Butcher (1999). Intramolecular Se...N nonbonding interactions in low-valent organoselenium derivatives A detailed study by IH and 77Se NMR spectroscopy and X-Ray crystallography. Chemistry—A European... 

The 33S isotope is quadrupolar (I = 3/2) and has low natural abundance (0.76%). Therefore, 33S NMR spectroscopy has found very limited application in S-N chemistry. On the other hand, both selenium and tellurium have isotopes with I = 1/2 (77Se, 7.6% and 125Te, 7.0%), and NMR studies using these nuclei can provide useful information for Se-N and Te-N systems. 

The advantage of this synthetic approach over the total synthesis of selenocysteine peptides is the reduced number of synthetic steps to which the Se-protected selenocysteine is exposed, thus, largely preventing deselenation as an undesired side reaction. It also allows access to larger peptides and even proteins containing selenocysteine to exploit the Se atom for X-ray crystallography, 13 or as 77Se nucleus for NMR spectroscopy. 60 ... 

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