Nuclear Magnetic Resonance Studies of Hydrosilanes. III. A Correlation of Hammett ? Constants with 29Si-H Coupling Constants for Substituted Phenoxy- and (Phenylthio)dimethylsilanes

Article abstract of DOI:10.1246/bcsj.53.2981

The 29Si-H coupling constants and Si-H chemical shifts have been determined for a series of substituted phenoxy- and (phenylthio)dimethylsilanes.The J(29Si-H) values are shown to be correlated well with the Hammett ? constants for the substituent on benzene ring in compounds Ar-Y-SiMe2H, where Y=O and S.In comparison with the data for the analogs of the other types of organodimethylsilanes, such as aryldimethylsilanes, substituted benzyldimethylsilanes, and aryltetramethyldisilanes, the present results are discussed on the basis of the substituent effects through theintervening oxygen and sulfur.The transmission efficiency of Y was in the order, S > CH2 ca.SiMe2 > O.For the series of (phenylthio)dimethylsilanes, the J(29Si-H) values observed were larger than those for the predicted ones.This deviation was interpreted in terms of the sulfur d-orbital participation via the electron-acceptor, "?-?" conjugation.