The mechanism of this transformation will be elucidated in a forthcoming separate study. All compounds reported herein have been characterised by elemental analysis, powder and singlecrystal XRD, ATR-IR spectroscopy, and 1 H, C( 1 H}, F, and Si{ 1 H} NMR spectroscopy (Figures ). The spectroscopic data agree with the crystallographically-determined structures; the composition and connectivity of the respective alkenyl and allylic moieties of 1-Y and 2-Y are unambiguous from their NMR spectra.