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 describ ed. Examination of how the C-13 chemical shifts of the ring carbons of subs tituted 2-pyridones change on complexation of the oxygen with silicon has e nabled the % Si-O bond formation to be determined in solution for a number of pentacoordinate silicon species with 2-pyridones as ligands. The % penta coordination in these complexes has been determined from the Si-29 chemical shift using model compounds for the tetracoordinate and pentacoordinate li miting cases. Correlation of the % Si-O bond formation with % pentacoordina tion enables the pathway for substitution at silicon to be mapped in soluti on. The generality of these techniques is examined using a series of relate d aromatic ligands.