Bis(trifluoromethyl)methylene Addition to Vinyl-Terminated SAMs: A Gas-Phase C–C Bond-Forming Reaction on a Surface

Vinyl-terminated self-assembled monolayers (SAMs) on silicon oxide substrates were chemically modified by the addition of a bis­(trifluoromethyl)­methylene group in a rare gas-phase C–C bond-forming reaction to directly generate films carrying terminal CF₃ groups. The vinyl-terminated films were treated with hexafluoroacetone azine (HFAA) for modification. The films were characterized with ellipsometry, contact angle measurements, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). In this study, we find that for optimized conditions clean reactions occur on a surface between SAMs with terminal olefins and HFAA, and the product is consistent with bis­(trifluoromethyl)­cyclopropanation formation after nitrogen extrusion.