19F Chemical Shifts and Infrared C-F Stretching Frequencies for Bridgehead Fluorides

Several 3-substituted-1-fluoroadamantanes and 4-substituted-1-fluorobicyclo (2.2.2) octanes have been synthesized. The 19F chemical shifts and C-F stretching frequencies for these bridgehead fluorides have been measured. The 19F substituent chemical shifts (SCS) extended the previously reported correlation of anomalous substituent effects on 19F chemical shifts of bridgehead fluorides. These 19F chemical shifts are incompatible with both theoretical and experimental explanations for proton chemical shifts, where comparable. The C-F stretching frequencies shifts (SFS) are anomalous when compared to the corresponding C-H data. Limited experimental data preclude a meaningful explanation at this time. (Author)