Aromatic compounds 13CNMR

Dimercury(I) n complexes are formed between aromatic compounds and Hg2(AsF6)2 in liquid S02 as solvent.113,121 Insoluble complexes with the ratio arene Hg2+ = 1 1 (arene = benzene, naphthalene, 2-methylnaphthalene, 2,6-dimethylnaphthalene, acenaphthene, fluor-anthrene, phenanthrene, anthracene, 9,10-dimethylanthracene or 1,3-dinitrobenzene) or 1 2 (arene = 9,10-benzophenanthrene) have been characterized by elemental analysis and, in some cases, by Raman spectrometry.113,120 The 13CNMR data allow the estimation of formation constants for the hexamethylbenzene, p-xylene and 1,4-dichlorobenzene complexes together with the chemical shifts for the bound substrates in these cases.121 Probably the coordination compounds of dimercury(I) salts with carbazole, dibenzofuran and diben-zothiophene are also n complexes.122... 

The 13C NMR chemical shifts of non-aromatic isothiazoles can be predicted with reasonable accuracy using standard substituent increments. A particular usefulness of 13C NMR is its ability to distinguish between very similar compounds, and for this reason 13C NMR finds application in pharmaceutical and other analyses. As an example 13CNMR allows ready distinction of the diastereoisomers of dehydromethionine (14) and the possibility of detection of one diastereoisomer in the presence of the other (79JOC2632). 

The 13CNMR spectrum of the 1,3-benzodioxolium ion (33), prepared in fluorosulfonic acid-sulfur dioxide solution from the methoxy compound (32), shows aromatic ring carbons deshielded 6.8 and 10.6 p.p.m. from the corresponding carbon atoms in (32). The chemical... 

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