STRUCTURAL STUDY OF ARYLSILANES USING SI-29 NMR

Si-29 NMR data (delta and H-1, Si-29 coupling constants) of a series o f arylsilanes were studied in relation to their molecular structure. I t is shown that silicon chemical shift variation is too weak to allow empirical attribution. In contrast, Si-29, H-1 coupling constants acro ss the aromatic ring, especially the 3J, allow structural assignment. Generally, SPT experiments are sufficient to obtain these values. Howe ver, full attribution of polysilylated derivatives sometimes needs oth er experiments to identify all the silicons. A 2D J-resolved INEPT exp eriment is described and has proven to be an efficient method for Si-2 9 NMR signal identification. The usefulness of this approach is demons trated by the complete analysis of all the Si-29 lines in a trisilyl d erivative. An easy-to-use INEPT decoupled-type sequence is also propos ed for a rapid characterization of polysilylated derivatives or mixtur e of isomers.