This scheme suggests initial attack on halogen forming a resonance-stabilized anion and (R0) ZPX+, which has precedent in the formation of pentachlorocyclopentadienide ion from hexachlorocyclopentadiene and triethyl pho~ phite.~ When X= C1 and Y= C1 or F, attack must occur preferentially at X, and reaction proceeds via path A. When X= Y= F, the cation in the initially formed enolate complex now possesses the stronger PF bond, and ...
