Chem. shift nonequivalence was found in prochiral silylmethyl groups of chiral dimethylsilyl acetals. The difference in chem. shifts between the silylmethyl protons varied proportionally with the electronegativity of the chiral substituents. If the achiral part was an aryl group, the dimethylsilyl acetals containing electron-withdrawing substituents on the aryl ring had smaller differences. The important factor contributing to the magnitude of the differences was (p-d)p interaction between the empty d-orbit of the silicon atom and the lone-pair electrons of the oxygen atom and the anisotropy of the aromatic ring.

Key words: MOLECULAR STRUCTURE, SILOXANE, PROTON MAGNETIC RESONANCE SPECTROMETRY, CHEMICAL SHIFT, CHIRALITY, ANISOTROPY, INTERACTIONS, ISOCHRONISM