Modulating "jousting" C-F---H-C interactions with a bit of hydrogen bonding.

We have synthesized a series of molecules wherein very close C-F---H-C σ-bond interactions, which we have termed "jousting", can be perturbed through both red- and blue-shifted hydrogen bonding effects. These interactions were induced by the placement of various functional groups geminal to the H-C bond. "Jousting" interactions appear to be an admixture of F---H hydrogen bonding and C-H bond compression. The associated electronic effects from changes in the functional group at the X-position were also studied.