ハロゲン化メタン及びハロゲン化シランにおけるC-13及びSi-29 NMR化学シフトに対する塩素, 臭素及びヨウ素原子による置換基効果

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^<13>C and ^<29>Si NMR chemical shifts were measured for chloro-, bromo- and iodo-substituted compounds [X_nMH_<4-n>; M=C, Si; n=1〜4]. Also, the behavior of the chemical shifts for the carbon and silicon atoms in those compounds were investigated. The ^<13>C chemical shifts of chloro- substituted compounds were to a lower field in the order of mono, di, tri and tetrachloro-substituents, which could be explained by an inductive effect. The ^<13>C chemical shifts for iodo-substituted compounds were to a higher field with increasing number of iodine atoms in a molecule. Although the ^<29>Si chemical shifts of chloro- and bromo-substituted compounds were to a lower field in the order of mono and disubstituents, those for tri and tetrasubstituted compounds were to a higher field. The ^<29>Si chemical shift of monoiodo-substituted compound was to a lower field, while the chemical shifts were largely toward a higher field in the order of di, tri and tetraiodo-substituted compounds. This can probably could be attributed to the effect of a steric compression between the substituted iodine atoms.
1998-04-05