Modelling nucleophilic substitution at silicon in solution, using hypervalent silicon compounds based on 2-pyridones

A novel method for performing structure correlations in solution is described. Examination of how the C-13 chemical shifts of the ring carbons of substituted 2-pyridones change on complexation of the oxygen with silicon has enabled the % Si-O bond formation to be determined in solution for a number of pentacoordinate silicon species with 2-pyridones as ligands. The % pentacoordination in these complexes has been determined from the Si-29 chemical shift using model compounds for the tetracoordinate and pentacoordinate limiting cases. Correlation of the % Si-O bond formation with % pentacoordination enables the pathway for substitution at silicon to be mapped in solution. The generality of these techniques is examined using a series of related aromatic ligands.