On rapporte Ics resultats d'une dtude par resonance magnctiquc du proton et du carbonc 13 sur l'anisole, le thioanisole, le selenoanisole et le telluroanisole, ainsi que sur certains de lcurs derives l~orrr substituCs. Considdres comnie des niethyles substitues, ccs composds ont iln coniportement analogue h celui des halogenurcs dc methyle. On a pu mettre cn evidence u n c relation lineairc entre le cleplacenient chiniiqile des protons et cclui du carbone du niethyle dans la serie de l'anisole et dans les halogenures de mcthyle h la fois. Si ces resultats s'interpretent le plus souvent i partir ci'cffcts electroniques, un "effet d'atomc Ioi~rd" doit Etre invoqud clans le cas dcs composes tellures. Les resultats experinientaux ne sont pas en desaccord avcc I'hypothese cl'une co~ifiguration plane des con~poses etudies.
GABRIEL LLABRES, MARCEL BAIWIR, LLON CHRISTIAENS, JOSE DENOEL, L~O P O L D LAITEM, and JEAN-LOUIS PIETTE. Can. J. Cheni. 56,2008 (1978).Results are reported of a study by ' H and "C nuclear magnetic resonance of anisolc, thioanisole, selcnoanisole and telluroanisole as well as of several of their prrrrr-substituted derivntives. I F these compounds are considered as substituted methyl groups, they display a behavioiir analogous to that of the methyl halides. I t is possible to demonstrate that a linear relation cxists between the proton and the carbon chemical shifts in the anisole scries as well as in the methyl halides. Although these results most frequently are interpreted in terms of electronic effects, a 'heavy atom effcct' must be invoked for the telluriuni con~pounds. The experimental results do not contradict the hypothcsis that the colnpounds studied have a planar configuration [Journal translation]
An important 13C NMR shielding effect on carbons bearing a heavy chalcogen is demonstrated. This effect is parallel to that induced by iodine, but to a lesser extent. For acyclic compounds and for partially saturated heterocycles, there is an excellent linear correlation between the "C chemical shifts of carbons bearing a chalcogen and carbons bearing a halogen atom in the corresponding compound. The linearity of the relationship is less satisfactory with heteroaromatic compounds.
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