Modelling nucleophilic substitution at silicon using solution 19F-NMR chemical shift, 1JS']JSi-F and 2JC-F coupling constant data of pentacoordinate silicon compounds.: Correlation with other magnetic nuclei and X-ray structures

Solution (1)J(Si-F) and (2)J(C-F) NMR coupling constant and F-19-NMR chemical shift data have been analysed in a series of pentacoordinate silyl monofluoride complexes used to model nucleophilic substitution at silicon. Patterns in the data reveal strong correlations between both coupling constants and F-19-NMR chemical shifts and the degree of substitution displayed by each. Excellent correlation is obtained between the new data and our previous C-13- and Si-29-NMR studies to further confirm the validity of the NMR technique for structural correlation in solution. By pooling the X-ray crystal structures of a large number of compounds of this class from both our own results and the literature we are able to provide a possible explanation for some of the trends in the NMR data we observe in solution. (C) 2003 Elsevier Science B.V. All rights reserved.