Reactivity of Fluorinated-Chalcone Phosphines, RPEWO‑F₄, Induced by C–F Activation upon Coordination to PdCl₂

The E phosphine ligands (R = Ph, o-Tol, Cy), abbreviated as RPEWO-F₄, are stable in solution, but they develop a rich reactivity on coordination to PdCl₂. The chelate P-olefin coordination to PdCl₂ leads eventually to a Z conformation of the fluorinated-chalcone group o-C₆F₄CHCHC­(O)­Ph. From there, a cyclization reaction occurs involving the CO group and activation of a F atom, yielding a strongly chelated PdCl₂(P-carbene) complex. The carbene carbon atom in the complex displays some electrophilicity, which is expressed in hydrolysis, ammonolysis, and oxidation (with peroxide) reactions, affording PdCl₂ complexes with new P,C,O-pincer, P,C,N-pincer, or P,O-chelate fluorinated ligands. The C–F activation reactions are slow in comparison to the catalysis rates when the [PdCl₂(RPEWO-F₄)] complexes have been used in Negishi catalyses. Consequently, the reactivity discussed here is not expected to interfere with the interpretation of the data obtained in Pd-catalytic studies or processes, at least for fast transmetalating nucleophiles.